Since the late 1950s, many UK hams (and some other European ones too) have been fixated on the 4 metre/ 70MHz band. I guess that includes me.
This is not the place to account for the history of this rather odd allocation. Later maybe. But many VHF enthusiasts find that it is the perfect meeting ground for a variety of conditions not shared by surrounding bands.
It gets:-
more tropo than 50MHz;
more Sporadic E than 144MHz,
antennas with an ideal size/gain combination and;
it is (arguably) the best band for meteor scatter.
Also, it is a hidden gem. There are very few commercial rigs. You have to be a "special" amateur enthusiast to work it.
The only real way to get onto 4m is to assemble some bits and plug them together. This "high technical requirement" thins out the numbers with the capability to get on the band. (Now that IS sarcasm). Some real enthusiasts built their own gear. Many have built the "OZ" transverter. Some bought the FT-847, some versions of which theoretically can work on 4m. However, those people soon found that the FT-847 needed as much effort to get going as would have built several OZ transverters.
But more of that later.
Latest news is that Germany has issued another limited time permit for full licencees to operate on 4m. This time it covers 70.150 to 70.180, 25W ERP. There was similar thing last year, but it had a much less friendly allocation of frequencies down in the beacon portion. So this is good news. Also, this one runs from now until the end of August 2015, so it covers most of the 4m Es season.
4m coverage tends to expand in this way. Certain German licencees already have single frequency allocations on 69.950 and 69.990. That was good start. Then we had the bottom slice of band opened up for a fixed period last year. Then an even better slice of band opened up this year. Maybe one day we will have even better terms. It will all work if we behave ourselves and do not cause any interference to other non-amateur operators.
The current Spanish allocation was something similar. First Spanish operators appeared on the band and then left again. Fixed term licences. Then they were back, then they left again. Then they stayed but on a conditional basis. Now, this year, they have a slice of the band on a permanent basis.
These slices of band rarely overlap. We have to resort to split frequency operation (Macedonia has two fixed frequencies 70.075 and 70.275, Lithuania has 70.240 to 70.250 - work that one out). Do we care? No. It just makes for more challenges. Any slice of band is helpful. It is not easy but who said it should be?
The downside of all this is the situation in Italy. As of this minute, Italian amateurs do not have 70MHz. They have had repeated short spells of operation over the past few years. That must be frustrating for the many keen Italian VHF amateurs. It is ironic that many other amateurs use Italian made (Sirio) antennas.
One of my favourite contacts on any band was working IK3FKX on 4m FM. To say that he was amazed would be an understatement, as he was having a cross town natter on a PMR (old taxi radio). We proceeded in a mix of half-English, half my schoolboy Latin, and he sent me a pile of material in the post which I still have on my pin board.
The present situation is a real step forward over the days when I was first licenced. Then, the only countries which had the band were UK, Republic of Ireland and Gibraltar. But we knew that it had potential. I give full credit to the many who worked hard behind the scenes to get the European band we now have.
"The problem", if there is one, behind getting more countries onto the band, is that these frequencies are often used for "state" purposes. So we need to tread carefully. Often, there have to be agreements with defence users, or there are certain frequencies allocated to PMR users. There are border issues between states. Over time, though, these can often be solved. In Russia and a few related states it is used for broadcasting, so that is a harder nut to crack.
As for "the rig problem" - I have heard enough of it. It does not exist.
I was reading a thread on another site about how terrible it is that the Yaesu FT-991 does not have 70MHz. Eh? Of course it doesn't. The FT-991 has an IF in the region of 70MHz. It would be hideously difficult to get it to work on 70MHz. If people cannot work out a simple technical issue like that, they will never get far on 70MHz. We have the IC-7100, a good way on to the band at a reasonable price. We have Spectrum transverters, which are good value for money. We have ME4T transverters for the more committed, and the Kuhne ones for the people who should be committed (seriously good kit, those). Then we have good commercial kit on FM for anyone who wants to get round Europe from time to time. Why do we need more rigs?
My simple guide to a way on to 4m for the non-technical.
1) Buy rig.
2) Buy transverter
3) Buy antenna patch leads
4) Plug together
5) Switch on
I do not believe that this is a barrier to entry, but I may be wrong of course.
Let me give you an example. 6m is a very good band. When it first appeared in Europe, almost no rigs in the UK covered 6m and the band was fragmented in different states. People said there should be more rigs. Over time, almost every HF rig now comes with 6m. Most European countries now have a common band. Are there many people on the 6m band? No.
This is not about the rigs. 6m is a brilliant band, but I know dozens of amateurs who have 6m rigs who do not ever set foot on 6m. The same goes for 2m. The idea that more easily available 4m rigs would change the band is ludicrous. The band will still be the band it is, no matter how much those lazy non-operators complain.
VHF dx is a dedication rather than an easy way of doing amateur radio. Even on 2m, the bands in Europe have a fraction of the activity they had in the days I was first licenced. VHF (6m, 4m and 2m) is a specialist sport, a place apart. It is a space in which you have to be ready to listen to hours of white noise. To transmit for a hour, and hear no reply (I just did that very thing). It has to be difficult because it is difficult. But when it works, it is glorious.
If 20 metres SSB is the football of radio, or 2m FM on a repeater is the gentle stroll, 2m SSB is a marathon, 6m is the Tour de France and 4m is an Iron Man Triathlon. To suggest that it should be made easier is like suggesting that Vincenzo Nibali would do better on a motor bike, or that Mo Farah would go faster in a 4x4.
I am away to try to work Germany.
Do you think I am still angry?
73
Jim
Thursday, 30 April 2015
Wednesday, 29 April 2015
Fault finding the FVM (angry) way
Grrr. I was SO angry yesterday. I was tearing my hair out and blaming everybody for what was going wrong with my Flex 1500.
I called CQ on meteor scatter on 70.230. I was called by EI4KF. We could not finish the QSO after an hour. He could hear me, but I could not hear him.
This is what Erik was seeing (rig 1 is the Flex/ME4T) ...
I only have a blank screen to show.
I tried both the Flex/ME4T combination, and the IC-7100 but it was mostly Flex/ME4T.
I got one burst from Erik which gave me his callsign and report. Apart from that I heard nothing, yet he could hear me both by tropo and by meteor scatter. I sense that this had happened before with other stations using data modes.
This is very frustrating as he had spent a lot of his time and I was getting nowhere.
It almost seemed as if I could hear weak signals in the speakers which were not decoding in the WSJT software.
It is true that he was running his full legal power (50 watts) and I was running 125 watts. Also, I have a 3dB higher noise level in his direction. But still, that was a poor result at my end.
I can cut a lot of this description out. I can save you the 24 hours of jiggling I did to pin the blame down to the virtual audio cable (VAC) level coming out of the Flex. I eliminated the WSJT software, the VACs themselves (by loading different VACs which were worse), and in fact everything else. It HAD to be the VAC output from the Flex. That was as far as I got when I stormed out yesterday evening.
The problem boiled down to this. I could turn the pre-amp on and off and that produced a 12dB change in the noise on the Flex waterfall and on the speakers. But the VAC was unchanged, as shown by the noise level on the WSJT software. Something was acting to keep the VACs 100% full of noise.
Eventually I noticed that the Flex "AGC-T" slider does not work as I had expected on VAC. Certainly, it reduces the noise on the display and the speakers. However, at the default setting of 90 it was stopping the WSJT software reacting to changes in level from the receiver. In effect it was overdriving the VAC at that level, though nothing was apparent on the screen or on the speaker. Reducing the AGC-T to 73 restored normality. that setting produced the same 12dB reduction in the VAC output as shown on the screen and heard in the speakers.
So basically the output to the VACs was being overdriven on receive, unknown to me.
I have no idea why the output to the VACs would be overdriven when the display and speakers showed no problem. The VACs themselves were fine, and reducing their gain controls just meant that the overdriven signal reduced in volume at the other end. So whatever it is occurs inside the PowerSDR software not the VACs.
I have now read a lot more about the AGC-T settings. I certainly looks as if Flex think that they should be adjusted on a band by band if not QSO by QSO basis. No chance of that here with data and so forth in operation. However, I can see that my combinations of filters, pre-amp and band settings on the Flex may have got things out of kilter.
So I have re-set AGC-T to 73. Let us see what happens next. Certainly, the beacons sound good on it. The spin off on the screen and speakers seems to be beneficial too.
I am still suffering with the cold. Maybe that is why I got so cross with all this. I had to shut down and leave the room. I was REALLY ANGRY. Not angry with the rig, angry with myself for not knowing what was wrong, and wasting Erik's time. Plus I need his square! I took it out on my new rig which was ordered in December and still has not arrived. I fired off some emails and generally got my frustration over that out too.
Sometimes I think it is not necessarily bad to blow your top. I have put up with a lot over the non-appearance of this mystery rig. So it was time to express that. The issue with the Flex just got me wound up ready to fire.
Anyway, normality has been restored for a while.
I need to work some DX on meteor scatter to prove everything is OK. And maybe take an "anger management" course.
Jim
GM4FVM
P.S. Just worked OK2BRD at 1528km. Seems to be working?
I called CQ on meteor scatter on 70.230. I was called by EI4KF. We could not finish the QSO after an hour. He could hear me, but I could not hear him.
This is what Erik was seeing (rig 1 is the Flex/ME4T) ...
I tried both the Flex/ME4T combination, and the IC-7100 but it was mostly Flex/ME4T.
I got one burst from Erik which gave me his callsign and report. Apart from that I heard nothing, yet he could hear me both by tropo and by meteor scatter. I sense that this had happened before with other stations using data modes.
This is very frustrating as he had spent a lot of his time and I was getting nowhere.
It almost seemed as if I could hear weak signals in the speakers which were not decoding in the WSJT software.
It is true that he was running his full legal power (50 watts) and I was running 125 watts. Also, I have a 3dB higher noise level in his direction. But still, that was a poor result at my end.
I can cut a lot of this description out. I can save you the 24 hours of jiggling I did to pin the blame down to the virtual audio cable (VAC) level coming out of the Flex. I eliminated the WSJT software, the VACs themselves (by loading different VACs which were worse), and in fact everything else. It HAD to be the VAC output from the Flex. That was as far as I got when I stormed out yesterday evening.
The problem boiled down to this. I could turn the pre-amp on and off and that produced a 12dB change in the noise on the Flex waterfall and on the speakers. But the VAC was unchanged, as shown by the noise level on the WSJT software. Something was acting to keep the VACs 100% full of noise.
Eventually I noticed that the Flex "AGC-T" slider does not work as I had expected on VAC. Certainly, it reduces the noise on the display and the speakers. However, at the default setting of 90 it was stopping the WSJT software reacting to changes in level from the receiver. In effect it was overdriving the VAC at that level, though nothing was apparent on the screen or on the speaker. Reducing the AGC-T to 73 restored normality. that setting produced the same 12dB reduction in the VAC output as shown on the screen and heard in the speakers.
So basically the output to the VACs was being overdriven on receive, unknown to me.
I have no idea why the output to the VACs would be overdriven when the display and speakers showed no problem. The VACs themselves were fine, and reducing their gain controls just meant that the overdriven signal reduced in volume at the other end. So whatever it is occurs inside the PowerSDR software not the VACs.
I have now read a lot more about the AGC-T settings. I certainly looks as if Flex think that they should be adjusted on a band by band if not QSO by QSO basis. No chance of that here with data and so forth in operation. However, I can see that my combinations of filters, pre-amp and band settings on the Flex may have got things out of kilter.
So I have re-set AGC-T to 73. Let us see what happens next. Certainly, the beacons sound good on it. The spin off on the screen and speakers seems to be beneficial too.
I am still suffering with the cold. Maybe that is why I got so cross with all this. I had to shut down and leave the room. I was REALLY ANGRY. Not angry with the rig, angry with myself for not knowing what was wrong, and wasting Erik's time. Plus I need his square! I took it out on my new rig which was ordered in December and still has not arrived. I fired off some emails and generally got my frustration over that out too.
Sometimes I think it is not necessarily bad to blow your top. I have put up with a lot over the non-appearance of this mystery rig. So it was time to express that. The issue with the Flex just got me wound up ready to fire.
Anyway, normality has been restored for a while.
I need to work some DX on meteor scatter to prove everything is OK. And maybe take an "anger management" course.
Jim
GM4FVM
P.S. Just worked OK2BRD at 1528km. Seems to be working?
Tuesday, 28 April 2015
My HF antenna, the Sirio Gainmaster.
This is not going to be easy to illustrate as I cannot get an effective photo of it. It is 7.36m tall from the base to the tip, so I need a pretty wide angle lens to get it all in.
I tried and this is the result. Most of the photo is the Tennamast; the Srio is on the left.
The wind seems to be catching it as it is not quite vertical. I see that Sirio recommend using guys in certain situations:-
- Locations subjected to strong wind or constant gusts of wind (eg: coast and mountain areas).
- Locations with cold winter conditions and frequent formation of ice layers on the antenna body. In fact, the different distribution of the weight, can change substantially the resistance to the wind.
We therefore recommend at least 3 ties "NYLON" bracing to be fixed at the junction between 2° and 3° fiber pipe (see drawing).
Anyway, I like balanced antennas and I do not like "ground plane" antennas. The ground here is VERY dry and sandy. There is no ground plane to be had here, and I would need to add lots of radials. I had been toying with the idea of a vertical dipole but they are hard to construct. You need to support them in the middle and run the co-ax away at right angles, which means very heavily built supports.
While I was thinking about how to do this, I discovered that Sirio make this vertical dipole, basically as a CB antenna. The details are on the Sirio website here. I bought it on eBay from a supplier in England I have used a lot and it cost about £100. Not cheap.
It seems to be a "sleeve dipole" or a "co-axial dipole". With this design you basically take a length of co-ax and strip the braid off the last 1/4 wavelength. This becomes half your antenna, and the 1/4 wavelength of braid before the stripped bit becomes the other half. Straight away this is not very satisfactory, and you need some method of isolating the braid part of the antenna from the rest of the co-ax, as otherwise unbalanced currents flow down your co-ax and give you all sorts of SWR problems.
I do not know how Sirio have dealt with this (everything is encapsulated) but there is a large coil of red co-ax at the bottom of the antenna.
I guess that this coil is in fact a "choke balun" designed to stop currents on the co-ax braid. That would isolate the rest of the co-ax from the currents in the antenna portion of the braid. A choke balun is not really a balun in the conventional sense (it is not a "transformer"), but it does tend to act as a choke to stop currents on the braid.
So far, so good. The two main features of the Gainmaster are understood by me. I did look long and hard at the publicity before I bought one. Vertical sleeve dipole - OK I get that: choke balun - yes, use those, fine. But Sirio had another trick up their sleeve (dipole). The antenna is not 1/2 wave in total length but 5/8 wave. It has long been known that 5/8 is a better radiator than 1/4 or 3/4 wave. The disadvantage of this is that it needs a matching circuit to make it usable on 50 ohm co-ax (all those coils on the bottom of mobile whips do that). So that Gainmaster has a matching circuit (I think a capacitor and a coil - I forget) matching the impedance at the point where the braid is cut. Clever.
I do not know now why a 5/8 has good radiation efficiency. Maybe I did know once and I have forgotten. Anyway we do not need a string of complex formulae, let us just accept it as a fact. If you know, there is no need to write in and tell us - unless you really want to.
So this is not just a vertical 1/2 wave dipole but a 5/8 wave vertical dipole (or 0.625 wavelength as Sirio call it). No fractions in Roman numerals? The elements are copper inside a fibreglass outer whip. You get the whip in four sections and the elements wrapped up. There is a bit of assembly to do. The ends of the fibreglass sections are split and held by "Jubilee clips" aka "worm drive hose clips". I wrapped the joints in the fibreglass with self amagamating tape which has lasted three years and now needs to be replaced.
I did some tests comparing the Sirio with a driven element of my G4MH mini-beam. So that was roughly 1/2 wave horizontal dipole compared to 5/8 wave vertical dipole. I used two separate rigs and compared transmission and reception reports for the same stations over the same paths at the same time. WSPR is great for these tests. The Sirio never did worse than the horizontal dipole, and nearly always did better. This was despite me turning the horizontal dipole right at the stations. So I took the horizontal dipole off the mast and it has been the Sirio ever since.
The Sirio has some drawbacks. It is one band only - though I do use it on 12 metres sometimes. The antenna it replaced covered 10m, 15m and 20m. On the other hand it works brilliantly well. There is nothing to do but put it up. It needs no radials, no counterpoises, no tuning and you do not need to rotate it. VK on half a watt - no problems. And - perfect for WSPR - it is omni-directional.
Personally, I think it is great if you like the 10 metre band. It is a real DX antenna.
73
Jim
GM4FVM
I tried and this is the result. Most of the photo is the Tennamast; the Srio is on the left.
- Locations subjected to strong wind or constant gusts of wind (eg: coast and mountain areas).
- Locations with cold winter conditions and frequent formation of ice layers on the antenna body. In fact, the different distribution of the weight, can change substantially the resistance to the wind.
We therefore recommend at least 3 ties "NYLON" bracing to be fixed at the junction between 2° and 3° fiber pipe (see drawing).
While I was thinking about how to do this, I discovered that Sirio make this vertical dipole, basically as a CB antenna. The details are on the Sirio website here. I bought it on eBay from a supplier in England I have used a lot and it cost about £100. Not cheap.
It seems to be a "sleeve dipole" or a "co-axial dipole". With this design you basically take a length of co-ax and strip the braid off the last 1/4 wavelength. This becomes half your antenna, and the 1/4 wavelength of braid before the stripped bit becomes the other half. Straight away this is not very satisfactory, and you need some method of isolating the braid part of the antenna from the rest of the co-ax, as otherwise unbalanced currents flow down your co-ax and give you all sorts of SWR problems.
I do not know how Sirio have dealt with this (everything is encapsulated) but there is a large coil of red co-ax at the bottom of the antenna.
I guess that this coil is in fact a "choke balun" designed to stop currents on the co-ax braid. That would isolate the rest of the co-ax from the currents in the antenna portion of the braid. A choke balun is not really a balun in the conventional sense (it is not a "transformer"), but it does tend to act as a choke to stop currents on the braid.
So far, so good. The two main features of the Gainmaster are understood by me. I did look long and hard at the publicity before I bought one. Vertical sleeve dipole - OK I get that: choke balun - yes, use those, fine. But Sirio had another trick up their sleeve (dipole). The antenna is not 1/2 wave in total length but 5/8 wave. It has long been known that 5/8 is a better radiator than 1/4 or 3/4 wave. The disadvantage of this is that it needs a matching circuit to make it usable on 50 ohm co-ax (all those coils on the bottom of mobile whips do that). So that Gainmaster has a matching circuit (I think a capacitor and a coil - I forget) matching the impedance at the point where the braid is cut. Clever.
I do not know now why a 5/8 has good radiation efficiency. Maybe I did know once and I have forgotten. Anyway we do not need a string of complex formulae, let us just accept it as a fact. If you know, there is no need to write in and tell us - unless you really want to.
So this is not just a vertical 1/2 wave dipole but a 5/8 wave vertical dipole (or 0.625 wavelength as Sirio call it). No fractions in Roman numerals? The elements are copper inside a fibreglass outer whip. You get the whip in four sections and the elements wrapped up. There is a bit of assembly to do. The ends of the fibreglass sections are split and held by "Jubilee clips" aka "worm drive hose clips". I wrapped the joints in the fibreglass with self amagamating tape which has lasted three years and now needs to be replaced.
I did some tests comparing the Sirio with a driven element of my G4MH mini-beam. So that was roughly 1/2 wave horizontal dipole compared to 5/8 wave vertical dipole. I used two separate rigs and compared transmission and reception reports for the same stations over the same paths at the same time. WSPR is great for these tests. The Sirio never did worse than the horizontal dipole, and nearly always did better. This was despite me turning the horizontal dipole right at the stations. So I took the horizontal dipole off the mast and it has been the Sirio ever since.
The Sirio has some drawbacks. It is one band only - though I do use it on 12 metres sometimes. The antenna it replaced covered 10m, 15m and 20m. On the other hand it works brilliantly well. There is nothing to do but put it up. It needs no radials, no counterpoises, no tuning and you do not need to rotate it. VK on half a watt - no problems. And - perfect for WSPR - it is omni-directional.
Personally, I think it is great if you like the 10 metre band. It is a real DX antenna.
73
Jim
GM4FVM
Sunday, 26 April 2015
Is it worth getting up early in the morning?
Normally, I would say that it is NOT worth getting up early in the morning. For radio, maybe, but for my general mood, NO.
This time I have had a cold. I have been coughing and spluttering. Mrs FVM has just finished two weeks working in London making the money to buy the rigs. She was totally exhausted and my coughing was waking her up. So I got up at 05:00. No point me keeping her awake.
I turned on the radios and set everything up, sat down to watch Frasier on the TV and fell asleep.
On WSPR I managed this:-
A two way to VK2KRR - well, only 50 minutes between me hearing him and him hearing me. I was hearing other VKs and JH1GYE. He was running 10 watts and I was running 0.5W. Generally most WSPR fans stick to 5W as the max. I am not going to increase to 5W just to be heard by a lot of stations. I want to see how well 500mW works and the World just needs to adjust to fit round me.
The only station to hear me between 05:00 and 08:45, so far, has been that one spot from VK2KRR. Yep, I am sure that some of the 50 or so stations I can hear could also hear me if I ran more power, but that would rather defeat my objects here. I was running low power, nobody in Europe could hear me, but I was heard 16,000km away. I like that.
Anyway, Frasier was over and the new 6m antenna has been tested. I heard SP2HRR pretty loud on the meteor scatter frequency of 50.230, calling for replies on 50.244. We then had a very quick QSO. It is still the end of the Lyrids meteor shower (missed most of that) so his signals were pretty easy to hear (and see!).
This is the sort of trace I like to see on meteor scatter. Nice strong pulses. Easily heard on the speaker. The QSO was over in less than 10 minutes.
JT6M, which is the mode most used on 6m, does have a lot of garbage coming up in the screen during QSOs. On FSK441, which is used on higher frequencies, you get much less garbage. However, FSK is not really suited to long periods of reception, it is more for very short bursts. Shorter than these ones anyway.
JT6M has been superseded by ISCAT, but most 6m operators stick to JT6M. Pity really. It must be frustrating for the developers to devise a new and better mode and find that amateurs do not take it up. I believe that PSK was devised to replace RTTY, which, sadly, it has not done. I do not like RTTY at all.
I think that a 1326km meteor scatter QSO, using an antenna with a boom length less than a metre, slung up just over the level of the roof, with a standard 100W transceiver, is pretty good. I keep hearing the cry "6m is dead" from people who cannot plug A into B and work some stuff. OK, the stations at the other end may have 6m booms and fancy kit, but you can do OK without it.
Speaking of which, cold or no cold, there was a break in the cloud and rain yesterday and I put up the Sirio 4m vertical again. Much lower than before but at least it is up for now. The locals were complaining that it is too low. Well, for now it will have to do.
My 4m FM rig is my propagation detector. It scans channels from 69.990 to 70.500, and it is great at spotting Sporadic E lifts. For that purpose the antenna does not need to be very high. Sporadic E, like meteor scatter and aurora, has signals arriving from quite a high angle. So the antennas do not need to be very high. I am not very bothered about not being able to hear locals on 6m or 4m, so they will have to accept this. The dx will get through.
Having said all that, both the 6m HB9CV and the 4m vertical will be going as high as I can get them in due course. Highest is best for dx, whatever the angle of propagation.
However, I have to proceed in gradual steps - ideally not spending any money as I go.
73
Jim.
This time I have had a cold. I have been coughing and spluttering. Mrs FVM has just finished two weeks working in London making the money to buy the rigs. She was totally exhausted and my coughing was waking her up. So I got up at 05:00. No point me keeping her awake.
I turned on the radios and set everything up, sat down to watch Frasier on the TV and fell asleep.
On WSPR I managed this:-
| 2015-04-26 07:00 | GM4FVM | 28.126087 | -24 | 0 | IO85wu | +27 | 0.501 | VK2KRR | QF34mr | 16748 | 10407 |
| 2015-04-26 06:56 | LZ1OI | 28.126043 | -25 | -1 | KN22jc | +40 | 10.000 | GM4FVM | IO85wu | 2463 | 1530 |
| 2015-04-26 06:56 | VK3AMW | 28.126024 | -29 | 0 | QF22ir | +37 | 5.012 | GM4FVM | IO85wu | 16797 | 10437 |
| 2015-04-26 06:10 | VK2KRR | 28.126041 | -18 | 0 | QF34mr | +40 | 10.000 | GM4FVM | IO85wu | 16748 | 10407 |
A two way to VK2KRR - well, only 50 minutes between me hearing him and him hearing me. I was hearing other VKs and JH1GYE. He was running 10 watts and I was running 0.5W. Generally most WSPR fans stick to 5W as the max. I am not going to increase to 5W just to be heard by a lot of stations. I want to see how well 500mW works and the World just needs to adjust to fit round me.
The only station to hear me between 05:00 and 08:45, so far, has been that one spot from VK2KRR. Yep, I am sure that some of the 50 or so stations I can hear could also hear me if I ran more power, but that would rather defeat my objects here. I was running low power, nobody in Europe could hear me, but I was heard 16,000km away. I like that.
Anyway, Frasier was over and the new 6m antenna has been tested. I heard SP2HRR pretty loud on the meteor scatter frequency of 50.230, calling for replies on 50.244. We then had a very quick QSO. It is still the end of the Lyrids meteor shower (missed most of that) so his signals were pretty easy to hear (and see!).
JT6M has been superseded by ISCAT, but most 6m operators stick to JT6M. Pity really. It must be frustrating for the developers to devise a new and better mode and find that amateurs do not take it up. I believe that PSK was devised to replace RTTY, which, sadly, it has not done. I do not like RTTY at all.
I think that a 1326km meteor scatter QSO, using an antenna with a boom length less than a metre, slung up just over the level of the roof, with a standard 100W transceiver, is pretty good. I keep hearing the cry "6m is dead" from people who cannot plug A into B and work some stuff. OK, the stations at the other end may have 6m booms and fancy kit, but you can do OK without it.
Speaking of which, cold or no cold, there was a break in the cloud and rain yesterday and I put up the Sirio 4m vertical again. Much lower than before but at least it is up for now. The locals were complaining that it is too low. Well, for now it will have to do.
My 4m FM rig is my propagation detector. It scans channels from 69.990 to 70.500, and it is great at spotting Sporadic E lifts. For that purpose the antenna does not need to be very high. Sporadic E, like meteor scatter and aurora, has signals arriving from quite a high angle. So the antennas do not need to be very high. I am not very bothered about not being able to hear locals on 6m or 4m, so they will have to accept this. The dx will get through.
Having said all that, both the 6m HB9CV and the 4m vertical will be going as high as I can get them in due course. Highest is best for dx, whatever the angle of propagation.
However, I have to proceed in gradual steps - ideally not spending any money as I go.
73
Jim.
Friday, 17 April 2015
Is the IC-7100 a bit deaf on 4 metres?
Someone on another site posed this question.
Is the IC-7100 a bit deaf on 4 metres?
In my view, yes. A bit.
Someone else said, it is "deafer than a deaf thing". That is going a bit far for me, but that is what he finds. I do always run a preamp in front of it, so he has a point.
Several people have done the best test possible - they have compared the IC-7100 with other rigs on their bench. That is a vastly better test than just replacing one rig with another and trying to remember what the first one was like. And that produces the impression (as they report) that the IC-7100 is better than a PMR FM rig (and so it should be). Then again, it is on a par with an older design of FM mobile and not quite as good as the latest multi-band mobile rigs. Interesting, but presumably that is on FM, which is hard to compare. You would expect it to be better than a £150 FM mobile and not worse than a £250 multi-band FM mobile, as it does cost over £1000.
Another person has compared the 7100 with a TS480 and a Spectrum transverter (a sensitive transverter that, or so I found with three of them at various times), and a Noble (now there is a good rig, how did he get one?) and he found the IC-7100 is worse than those.
Someone else uses a pre-amp which he says "transforms" the 7100.
Well, here I use the GaAsFET preamp and the pre-amps in the 7100 itself. And I compared that against the Flex 1500/ME4T-Pro transverter and the FT-817 and the same transverter. The transverter was better than the IC-7100 on both rigs, even the transverter with the FT-817. Just to remind you, the FT-817 is basically a 20 year old design of portable without DSP and costs half the price - though it does not cover 4 metres. Whereas the 7100 claims to be state of the art.
Worth thinking about this if 4 metres is all you are looking for --- don't write off transverters just yet. The FT-817 and the ME4TPro transverter, new, are cheaper than the 7100. Hardly comparable and I would not necessarily recommend it, but still if you are looking for a 4m rig ... and the ME4TPro and the Flex 1500 are about the same. You might expect the IC-7100 to outclass those combinations on 4 metres, but in many ways it does not. And the ME4TPro here is giving a full 33 watts on 4m SSB, the 7100 only 20 out of its claimed 50! The Spectrum is cheaper, did not perform as well as the ME4TPro for me, but by recent accounts can show a clean set of heels to the Icom. The Spectrum has other issues (frequency stability, power output and strong signal handling) but is not to be sniffed at by comparison with a far more expensive "all-singing all dancing" rig which has issues.
Of course a single band rig, such as the Noble, or a single band transverter, such as the ME4T or the Spectrum, can be tweaked for maximum performance on that one band. On the other hand, the IC-7100 is a multi-band rig with 4m as an add-on.
But what do I mean by "better"? Frankly, I think it is noise performance rather than sensitivity as such. I find that the transverter is best when I am straining with the cans on to find a weak beacon or something. That stands out from the noise better on the others than on the IC-7100. As an example, I might say that my first ME4T receiver section equal to the Spectrum, but the newer ME4T-Pro has a better low noise mixer and that shows in really weak signal performance.
Simply put, I can hear things on the ME4TPro that I can not hear on the IC-7100. In that way the transverter is "better".
The transverter does most of the work. The rig driving it can be quite simple, like the FT-817, though the added features of the Flex do make life much easier.
Unless you are straining for the last ounce of performance I doubt if the IC-7100 will let you down. But I am. And lets us not forget that I am using a high performance pre-amp as well. What it comes down to (for me) is not that the 7100 is insensitive, it is that it fails to perform well at really low signal levels where signal to noise is key.
Someone said, if I hear a weak signal on the 7100 and turn on the preamp it gets better. Right. I am saying I can hear things on other equipment that I cannot hear on the 7100, preamp or not. At some level a preamp will increase the noise, and if the wanted signal is not capable of being resolved by the rig, you are expecting a lot from a preamp to solve the problem. If the noise performance of the rig is not good enough then all you are doing is raising the level of the noise and the signal which is being swamped by noise inside the rig anyway.
My father always refused a hearing aid. He said that he could hear sounds, it was the clarity which he was lacking. I find that the IC-7100 is lacking the clarity he was talking about.
As I said in an earlier post, the IC-7100 has strengths and weaknesses. I am not changing anything I wrote then. However, I have moved the 7100 to 50MHz and 144MHz use here. I also feel that an FT991 might do that job better too. Whereupon my 7100 could become my multi-band FM rig, and the one I take on caravan trips. What a waste that would be.
It is OK. It could be a lot better.
73
Jim
GM4FVM
Is the IC-7100 a bit deaf on 4 metres?
In my view, yes. A bit.
Someone else said, it is "deafer than a deaf thing". That is going a bit far for me, but that is what he finds. I do always run a preamp in front of it, so he has a point.
Another person has compared the 7100 with a TS480 and a Spectrum transverter (a sensitive transverter that, or so I found with three of them at various times), and a Noble (now there is a good rig, how did he get one?) and he found the IC-7100 is worse than those.
Someone else uses a pre-amp which he says "transforms" the 7100.
Well, here I use the GaAsFET preamp and the pre-amps in the 7100 itself. And I compared that against the Flex 1500/ME4T-Pro transverter and the FT-817 and the same transverter. The transverter was better than the IC-7100 on both rigs, even the transverter with the FT-817. Just to remind you, the FT-817 is basically a 20 year old design of portable without DSP and costs half the price - though it does not cover 4 metres. Whereas the 7100 claims to be state of the art.
Worth thinking about this if 4 metres is all you are looking for --- don't write off transverters just yet. The FT-817 and the ME4TPro transverter, new, are cheaper than the 7100. Hardly comparable and I would not necessarily recommend it, but still if you are looking for a 4m rig ... and the ME4TPro and the Flex 1500 are about the same. You might expect the IC-7100 to outclass those combinations on 4 metres, but in many ways it does not. And the ME4TPro here is giving a full 33 watts on 4m SSB, the 7100 only 20 out of its claimed 50! The Spectrum is cheaper, did not perform as well as the ME4TPro for me, but by recent accounts can show a clean set of heels to the Icom. The Spectrum has other issues (frequency stability, power output and strong signal handling) but is not to be sniffed at by comparison with a far more expensive "all-singing all dancing" rig which has issues.
Of course a single band rig, such as the Noble, or a single band transverter, such as the ME4T or the Spectrum, can be tweaked for maximum performance on that one band. On the other hand, the IC-7100 is a multi-band rig with 4m as an add-on.
But what do I mean by "better"? Frankly, I think it is noise performance rather than sensitivity as such. I find that the transverter is best when I am straining with the cans on to find a weak beacon or something. That stands out from the noise better on the others than on the IC-7100. As an example, I might say that my first ME4T receiver section equal to the Spectrum, but the newer ME4T-Pro has a better low noise mixer and that shows in really weak signal performance.
Simply put, I can hear things on the ME4TPro that I can not hear on the IC-7100. In that way the transverter is "better".
The transverter does most of the work. The rig driving it can be quite simple, like the FT-817, though the added features of the Flex do make life much easier.
Unless you are straining for the last ounce of performance I doubt if the IC-7100 will let you down. But I am. And lets us not forget that I am using a high performance pre-amp as well. What it comes down to (for me) is not that the 7100 is insensitive, it is that it fails to perform well at really low signal levels where signal to noise is key.
Someone said, if I hear a weak signal on the 7100 and turn on the preamp it gets better. Right. I am saying I can hear things on other equipment that I cannot hear on the 7100, preamp or not. At some level a preamp will increase the noise, and if the wanted signal is not capable of being resolved by the rig, you are expecting a lot from a preamp to solve the problem. If the noise performance of the rig is not good enough then all you are doing is raising the level of the noise and the signal which is being swamped by noise inside the rig anyway.
My father always refused a hearing aid. He said that he could hear sounds, it was the clarity which he was lacking. I find that the IC-7100 is lacking the clarity he was talking about.
As I said in an earlier post, the IC-7100 has strengths and weaknesses. I am not changing anything I wrote then. However, I have moved the 7100 to 50MHz and 144MHz use here. I also feel that an FT991 might do that job better too. Whereupon my 7100 could become my multi-band FM rig, and the one I take on caravan trips. What a waste that would be.
It is OK. It could be a lot better.
73
Jim
GM4FVM
Thursday, 16 April 2015
Alpacas, work and propagation, almost.
It has been a busy couple of days. I have actually had to work. I am not so busy, generally, being a self employed part timer, that work gets in the way of important things like radio. But sometimes work has to be done. Self employment brings many benefits, but you feel you have to work when there is work to do.
I did manage to get out on my walk. 10,000 steps a day is the target and today so far it is 11,799 (yesterday 11671). Who said I was a "target man"? And I managed to see the alpacas. There are four but one was standing a bit far away. They are a long way from the Peruvian Andes, but it was cold enough last night for frost here. There are looking quite wooly now.
Anyway, the Sporadic E season has started here on 10 metres. It was good to see Gianfranco IU1DZZ on my WSPR waterfall. Mind you, I managed to lose the USB connection to the rig. So I posted Gianfranco's contact as on 12 metres, but it was indeed on 10m. I do not know definitely why this is happening, but I am pretty sure it is because the USB connector is on an outboard USB3 hub. I shall try to connect it more directly to the PC.
There was a general Es opening at fairly good strength from here into Northern Italy on 10m. It lasted from about 13:30 to around 17:00. There was also an opening on 6m along the same path but I heard nothing at all of that. So no 6m Es yet, nor anything on higher frequencies either.
The thing about working from home is that you can build your workplace at the back of the shack. So there I was, five rigs running, an Es opening on WSPR being copied, and muggins here working away whilst listening to the cricket on the computer. Multi-tasking I think it is called.
Later, around 19hrs I heard a very strong meteor scatter QSO on 70MHz. Try as I might I could not resolve either station. It sounded like ISCAT, looked like FSK, but neither mode would decode. I also tried JTMS but I was getting nowhere. Then, as I watched the Flex monitor, I noticed a CW station about 20kHz lower. Bounding down it was GM3WUX in Glasgow on aurora. Three cheers for the Flex panoramic display, where you can see stations you cannot hear.
I can only guess that the stations I could not decode were in the Nordic Activity Contest somewhere in Scandinavia, and the signals were so distorted by the aurora I could not copy them.
Of course I had no idea there was an aurora until I saw GM3WOJ. I could not raise WOJ. His signal faded and turned back into a non-distorted weak tropo tone. I heard GM4VVX quite strongly on aurora but I could not raise him either. I heard a Swedish 2m beacon too but that was it. I had a good chat with Andy GM8OEG and that was the day done.
The original plan, that is yesterday's plan, was for today to be doing antenna work. Then came the extra work, and sadly I could not get out apart from the walk. Still, watching the Es and hearing the aurora was good. However, the antenna work is still not done. The work task is not finished either, so it looks like tomorrow is accounted for too.
73
Jim
GM4FVM
I did manage to get out on my walk. 10,000 steps a day is the target and today so far it is 11,799 (yesterday 11671). Who said I was a "target man"? And I managed to see the alpacas. There are four but one was standing a bit far away. They are a long way from the Peruvian Andes, but it was cold enough last night for frost here. There are looking quite wooly now.
Anyway, the Sporadic E season has started here on 10 metres. It was good to see Gianfranco IU1DZZ on my WSPR waterfall. Mind you, I managed to lose the USB connection to the rig. So I posted Gianfranco's contact as on 12 metres, but it was indeed on 10m. I do not know definitely why this is happening, but I am pretty sure it is because the USB connector is on an outboard USB3 hub. I shall try to connect it more directly to the PC.
There was a general Es opening at fairly good strength from here into Northern Italy on 10m. It lasted from about 13:30 to around 17:00. There was also an opening on 6m along the same path but I heard nothing at all of that. So no 6m Es yet, nor anything on higher frequencies either.
The thing about working from home is that you can build your workplace at the back of the shack. So there I was, five rigs running, an Es opening on WSPR being copied, and muggins here working away whilst listening to the cricket on the computer. Multi-tasking I think it is called.
Later, around 19hrs I heard a very strong meteor scatter QSO on 70MHz. Try as I might I could not resolve either station. It sounded like ISCAT, looked like FSK, but neither mode would decode. I also tried JTMS but I was getting nowhere. Then, as I watched the Flex monitor, I noticed a CW station about 20kHz lower. Bounding down it was GM3WUX in Glasgow on aurora. Three cheers for the Flex panoramic display, where you can see stations you cannot hear.
I can only guess that the stations I could not decode were in the Nordic Activity Contest somewhere in Scandinavia, and the signals were so distorted by the aurora I could not copy them.
Of course I had no idea there was an aurora until I saw GM3WOJ. I could not raise WOJ. His signal faded and turned back into a non-distorted weak tropo tone. I heard GM4VVX quite strongly on aurora but I could not raise him either. I heard a Swedish 2m beacon too but that was it. I had a good chat with Andy GM8OEG and that was the day done.
The original plan, that is yesterday's plan, was for today to be doing antenna work. Then came the extra work, and sadly I could not get out apart from the walk. Still, watching the Es and hearing the aurora was good. However, the antenna work is still not done. The work task is not finished either, so it looks like tomorrow is accounted for too.
73
Jim
GM4FVM
Monday, 13 April 2015
Climbing, conditions and General Shufflebottoms returns
Argh! I never saw anything like it.
Doug, GM6ZFI arrived to help with the brackets, and promptly ignored the platform on the scaffold tower. He charged straight up the rungs at the side and balanced himself up there. I say balanced, he put his foot on one of the very weak crossbars - you can see it bend. He looks happy enough, and I can see why I did not do it that way.
The point is, Doug is a professional electrician and he is used to this type of thing. And he knows what is safe and what is not safe. He proceeded with great care, using protective clothing, goggles and ear protection, and it was real eye opener. He knows what he is doing, however scary it looks to me (I took that photo from a height: from underneath holding the scaffolding it felt that he was very high). It does look scary to me, which is proof that I was better to bring in someone who has spent years working up high.
What he has done is to lower the top bracket below what was the bottom one. It is now at a height that I can work on it safely from the platform on the scaffolding. Hopefully over the next few weeks I can get the 6m antenna sorted out once and for all (well, until I change it next time). Those brackets should be able to support something a lot better than the current HB9CV. Which would need a better rotator ...
I really appreciate what Doug did for me today. Doug is a real gent and a true radio amateur. He drove over here and did all this, provided the fixings, all for no payment. All I could get him to accept was coffee and a sausage roll in the Rialto Cafe in Eyemouth. I owe him several favours for that work today.
Yesterday and today brought Sporadic E to 6 metres in Europe. A couple of stations in Scotland got in on some of it, but nothing was heard from here.
10 metre conditions are still struggling. It took 43 hours of silence, during and after the geomagnetic storms, for me to receive just one spot - and then not another one for hours after that. Although there have been a couple of longer distance spots on WSPR, generally I have been getting weak spots from Belgium. Nice but not earth shattering.
Shufflebottoms is back. Having just recast everything in the shack, I have already swapped the HF and 4m rigs. Although the FT-817 was doing passably well driving the 4m transverter, I relented and put the Flex on that duty instead. The FT-817 is now on 10 and 12 metre bands.
There is some logic to that. It was the set-up here about a year ago. It allows me to run the transverter on 1mW rather than 5W. OK, the transverter has an attenuator to reduce the power if needed, but also the Flex can also use separate tx and rx leads. This means that, should I forget to turn the transverter on, or the PTT lead falls out, or some other failure occurs, then I am txing 1mW into a dead end. If I was using 5W from the single cable FT-817, I would be txing 5W into the receiver section of the transverter - which is expensive as it blows everything up. It has never happened to me, but I do not like tempting fate.
The FT-817 receiver is OK; the Flex has a better receiver. And for some reason the Flex is driving the transverter harder than it was. Whatever Gabi, HA1YA, did to the transverter when he gave it a make-over has done the trick. I have also provided the linear with a dedicated power supply right beside it to reduce voltage loss in the supply leads. All this means that I can get the full legal 150 watts output on 4m. Not that I am running more than 100W in normal service, of course.
So that is where we are today. If I decide that the Flex/transverter set-up is not very good on meteor scatter, which was my mad belief before (impossible, surely), everything will change ... again.
73
Jim
GM4FVM
Doug, GM6ZFI arrived to help with the brackets, and promptly ignored the platform on the scaffold tower. He charged straight up the rungs at the side and balanced himself up there. I say balanced, he put his foot on one of the very weak crossbars - you can see it bend. He looks happy enough, and I can see why I did not do it that way.
The point is, Doug is a professional electrician and he is used to this type of thing. And he knows what is safe and what is not safe. He proceeded with great care, using protective clothing, goggles and ear protection, and it was real eye opener. He knows what he is doing, however scary it looks to me (I took that photo from a height: from underneath holding the scaffolding it felt that he was very high). It does look scary to me, which is proof that I was better to bring in someone who has spent years working up high.
What he has done is to lower the top bracket below what was the bottom one. It is now at a height that I can work on it safely from the platform on the scaffolding. Hopefully over the next few weeks I can get the 6m antenna sorted out once and for all (well, until I change it next time). Those brackets should be able to support something a lot better than the current HB9CV. Which would need a better rotator ...
I really appreciate what Doug did for me today. Doug is a real gent and a true radio amateur. He drove over here and did all this, provided the fixings, all for no payment. All I could get him to accept was coffee and a sausage roll in the Rialto Cafe in Eyemouth. I owe him several favours for that work today.
Yesterday and today brought Sporadic E to 6 metres in Europe. A couple of stations in Scotland got in on some of it, but nothing was heard from here.
10 metre conditions are still struggling. It took 43 hours of silence, during and after the geomagnetic storms, for me to receive just one spot - and then not another one for hours after that. Although there have been a couple of longer distance spots on WSPR, generally I have been getting weak spots from Belgium. Nice but not earth shattering.
Shufflebottoms is back. Having just recast everything in the shack, I have already swapped the HF and 4m rigs. Although the FT-817 was doing passably well driving the 4m transverter, I relented and put the Flex on that duty instead. The FT-817 is now on 10 and 12 metre bands.
There is some logic to that. It was the set-up here about a year ago. It allows me to run the transverter on 1mW rather than 5W. OK, the transverter has an attenuator to reduce the power if needed, but also the Flex can also use separate tx and rx leads. This means that, should I forget to turn the transverter on, or the PTT lead falls out, or some other failure occurs, then I am txing 1mW into a dead end. If I was using 5W from the single cable FT-817, I would be txing 5W into the receiver section of the transverter - which is expensive as it blows everything up. It has never happened to me, but I do not like tempting fate.
The FT-817 receiver is OK; the Flex has a better receiver. And for some reason the Flex is driving the transverter harder than it was. Whatever Gabi, HA1YA, did to the transverter when he gave it a make-over has done the trick. I have also provided the linear with a dedicated power supply right beside it to reduce voltage loss in the supply leads. All this means that I can get the full legal 150 watts output on 4m. Not that I am running more than 100W in normal service, of course.
So that is where we are today. If I decide that the Flex/transverter set-up is not very good on meteor scatter, which was my mad belief before (impossible, surely), everything will change ... again.
73
Jim
GM4FVM
Sunday, 5 April 2015
Bands are better at the weekend
It is oft said that the bands are better at the weekend. That just means there are more stations active Friday to Sunday (or Monday for this week's European holiday).
Some good stuff so far this weekend.
I was doing my beacon search and GB3NGI was there strong as usual, but I FINALLY found GB3WGI.
OK, this is a beacon running 100W into a pair of 6 ele beams and only 396 km away in County Fermanagh, so you wouldn't think it would be that hard to do, even with a 10 ele tiddler at this end.
Nevertheless, I had never heard it before.
Maybe that is because this beacon is specifically designed to be heard on the far side of the Atlantic Ocean, so it is not exactly optimised for Scotland. Basically, for a UK beacon it could not be harder to hear from here.
So, it is done and another one is crossed off the "to do" list. In reality it shows that conditions are pretty good towards GI right now, so there must be some tropo about. I am hoping that tomorrow and Tuesday should be good too, based on the atmospheric pressure chart.
There was an RSGB 4m contest today which I almost forgot about. I was blasting away calling CQ on meteor scatter when I noticed that I was hearing the SSB of a certain station who reckons he is a 4m contester. I was beaming East and he is South of me, but all the same I heard him clearly. I just wish sometimes he would hear me. Or rather I wish he would LISTEN for me, as I reckon that listening is not his best skill. Eventually he might find that trying to work on the meteor scatter frequency used by almost everybody to call CQ will limit his results, even if he cannot hear us all blarging away on 100watts.
I came on for the last ten minutes of the contest. I managed to work G3TCU/P in IO91rf, 524km, Eddie, G0EHV (nearby) and David, G4ASR, IO81mx, 434km. The usual suspects. Not bad for ten minutes work.
Then I went back to calling on meteor scatter and worked OZ1JXY. Henning is a regular, despite the fact that according to the book he is too close to me (734km) and in the middle of the day (12:42) we should not be able to work. But we can. So much for the book.
I have just left the VLA-150 linear in the corner, so I am restricted to 20 watts on 6m for now. It smells so awful I do not want to open it.
73
Jim
Some good stuff so far this weekend.
I was doing my beacon search and GB3NGI was there strong as usual, but I FINALLY found GB3WGI.
OK, this is a beacon running 100W into a pair of 6 ele beams and only 396 km away in County Fermanagh, so you wouldn't think it would be that hard to do, even with a 10 ele tiddler at this end.
Nevertheless, I had never heard it before.
Maybe that is because this beacon is specifically designed to be heard on the far side of the Atlantic Ocean, so it is not exactly optimised for Scotland. Basically, for a UK beacon it could not be harder to hear from here.
So, it is done and another one is crossed off the "to do" list. In reality it shows that conditions are pretty good towards GI right now, so there must be some tropo about. I am hoping that tomorrow and Tuesday should be good too, based on the atmospheric pressure chart.
There was an RSGB 4m contest today which I almost forgot about. I was blasting away calling CQ on meteor scatter when I noticed that I was hearing the SSB of a certain station who reckons he is a 4m contester. I was beaming East and he is South of me, but all the same I heard him clearly. I just wish sometimes he would hear me. Or rather I wish he would LISTEN for me, as I reckon that listening is not his best skill. Eventually he might find that trying to work on the meteor scatter frequency used by almost everybody to call CQ will limit his results, even if he cannot hear us all blarging away on 100watts.
I came on for the last ten minutes of the contest. I managed to work G3TCU/P in IO91rf, 524km, Eddie, G0EHV (nearby) and David, G4ASR, IO81mx, 434km. The usual suspects. Not bad for ten minutes work.
Then I went back to calling on meteor scatter and worked OZ1JXY. Henning is a regular, despite the fact that according to the book he is too close to me (734km) and in the middle of the day (12:42) we should not be able to work. But we can. So much for the book.
I have just left the VLA-150 linear in the corner, so I am restricted to 20 watts on 6m for now. It smells so awful I do not want to open it.
73
Jim
Wednesday, 1 April 2015
Tennamast, my best accessory.
EDIT - I did replace the cables, see here https://gm4fvm.blogspot.com/2020/10/new-extension-cable-for-my-tennamast.html
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I seem to be having issues with checking out the radio insurance market - more on that later. I would like to share my happy experiences, but it is just a thankless chore, to be honest.
But it got me making an inventory of all my accessories. The best one I have is my Tennamast.
I have always wanted one of these, but it only arrived here about 5 years ago. Mine is the "Adapt-a-Mast" tilt-over type one, which is fixed to the house wall by extremely sturdy brackets. That is the safest method as far as I can see. No climbing, and the house offers wind protection.
I have no connection with Tennamast, I just like the product they made which I bought.
Tenna have a range of masts available, and they will ship them to many places. They are based in Scotland and when I spoke to them recently they had sent one to New Zealand. I am not surprised as they are a very effective product. I would say that, pound for pound, it is the most effective piece of equipment in my station.
The Adapt-a-Mast which I have is 7.6 metres. That is the smallest they sell. They recommend maximum height above the rotor of 2.1m, so 7.6+2.1 = 9.7m to the top, plus the rotator and lower mast, which makes about 1m possibly. Mine is about 10m as I do not use the full 2.1m above the rotator. At that maximum height the antennas cannot be seen from the road outside our house when the mast is lowered.
Also available from Tennamast is a rotator cage. I have recently bought a rotator cage but I am not using it yet.
You can also buy a 10m version of the Adapt-a-Mast. It is mainly intended for mounting on two storey houses. It might go on a gable end (I am not sure about this) but it is not what I am after. The extra height would help, but I am happy with what I have.
The shorter Adapt-a-Mast I have is a two section mast. The two main sections are square section alloy tubes which fit into each other. So the mast is raised and lowered by a winch (mine also tilts by a winch - see later). The smaller section sits inside the larger section, and is then pulled out to raise the mast.
Tenna make the Adapt-a-Mast in both non-tilting and tilting sytles - the non-tilting is cheaper as you do not need the winches, pulleys and wall bracket needed for tilt. As I have never been a good climber I chose the tilting one. Now I am a worse climber than before, so I need the tilt even more.
The standard winches supplied are good enough, but I opted to upgrade mine. You have to release the ratchet on the Dutton-Lainson winches to lower the mast or tilt it. I feared dropping the winch handle as it lowers, though that is pretty unlikely. Tenna offer braked ones, but they need back pressure to operate. Yes, they will brake, but only after a short fall or tilt. Yep, sure that is fine, but I installed a pair of Dutton-Lainson worm gear winches instead.
The point about worm gear winches is that they stay wherever you leave them - half wound up or fully wound up or wherever. They were not cheap, but they are very effective. No ratchets now. Doug, 2M0LAT kindly made a couple of hex bolts which fit into my power screwdriver and drill. Now I can wind the mast up and down, and tilt it over and back, with the battery powered drills. Simple. Doug also drilled out the winch frames to fit the Tenna brackets. Job done. Electric winches with no mechanics outside to rust, as the drills stay nice and warm charging in the house.
I always lower the mast when not in use. My neighbours should not need to look at it all day. Also, it protects it if the wind gets up overnight. Somewhere I saw a Google Streetview of our street with an image of the mast raised in the photo. They must have surveyed the street when it was in use. I only tilt it when I am working on the antennas, so it stays fixed to the wall by the brackets, lowered, most of the time.
Fixing for the mast is by the backets into the house wall. Each bracket is held by two expanding masonery Rawlbolts, four in total, plus the ground hinge fixing. When it tilts, the bottom hinge supports it. The bottom hinge is bolted into a buried concrete block, also fixed by four Rawlbolts. I do not remember now, but I think it is only a half metre square of concrete as the mast is supported by the tilt winch when tilted over. I bet for free standing masts you would need a lot more concrete - a square metre at least.
It was installed by two of us in a day's work divided into two sessions. Half a day to dig the hole and cast the concrete, then half another day to assemble it. We left the concrete for a few days to "go off" before doing the second half day's work. It arrived by truck but I could lift it on my own and carry it round the house.
Tenna also make free-standing versions of their masts, which tilt from a winch on a ground post. I did not want one of those for all sorts of reasons. I would guess that freestanding Tennamasts they are easier to manage than the classic trianglar lattice masts, but maybe they can carry a bit less headload than the heaviest lattice mast.
So there it is. At the moment I have a 6 element 4m beam, 2m dipole and a 10 element 2m beam on it. At various times I have had a two element HF mini beam, verticals, and assorted beams, and the joy is that I can tilt it over and shuffle them around. My antennas are changing regularly. It takes about 10 minutes to undo the brackets and tilt it over.
There must be some drawback. Not really except maybe that in the wind it rattles and groans a bit. This sound is the inner section bumping against the outer section. They have to be loose to allow for extending the mast. I do wonder though, could someone not design an angled wedge on the inner section which would fit against the outer section when lowered and hold the thing more firmly? But that is the sum total of my doubts.
There is of course the price to consider. It cost me about £650, whereas I could easily spend £2000 on a linear amplifier. That would add nothing to my received signals. By allowing me to put up better antennas the Tennamast let me improve both my received signals and also the signal arriving at the other end. Better value than a linear I think. I have linears too, but they are not a patch on this thing.
I will put a link to Tenna's site on the right of my blog.
73
Jim
GM4FVM
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