A Learning curve

A few weeks back I picked up this linear Amplifier on Ebay. Now in the 25 years or so that I have been licenced I have never run more than 100 watts or so maximum RF power and usually less. So why a linear? Well my original idea was to be able to use it on data modes, under running it so that perhaps with 10 or so watts from the rig I would get 50 or so from the amp. Of course I would use it on SSB from time to time. This is a valve linear but the prospect of tuning it up wasn't a problem as I am used to that with my TS830 and other rigs I have used in the past.

When the unit arrived here it all looked OK (and I should point out that I believe it was most likely working properly before it was sent but I don't think a journey through the postal system is good for equipment like this!)  so eager to test it out I connected up to my rig and a dummy load and switched on. The next thing I heard was a "pop" sound and I was sitting in darkness, no computer radio or anything- the linear had tripped the household RCD circuit. After a reset and replacing the internal fuse in the linear I tried again. I managed to get around 150 watts into the dummy load before the internal fuse went again, no surprise this time as I needed a 2.0A fuse but had only 315MA available. A few days later I got hold of a 2a fuse. Ran the linear up and before I could apply any RF to it "BANG!!" a capacitor on the output stage blew. I have an amateur friend locally who is skilled at electronics generally and he had a look at the circuit diagram. The blown capacitor was 3600pf, voltage rating unknown.

 He worked out that be using four lower rated capacitors 2 pairs in parallell, connected in series that should be ok. well I connected the new capacitors and much to my surprise everything was working well.

 So with a certain sense of satisfaction I had repaired the linear. All was well until today when I find that there is no current on the anodes of the valves according to the front panel meter and I can get no RF out of the linear. What has blown now? another capacitor? I cannot see anything obvious so I will be looking for advice from my G3 friend again.
You most likely will not recognise this model of linear from the pictures. I think it was manufactured in the 1980s/90s. It is an "SRW kilowatt loudenboomer" which actually produces a maximum of 400 watts out. If I ever get it working I will write a little more about it as currently there is very little information on the net.

Given my very limited electronics skills  this is a real learning curve for me, I am very fortunate that I have an experienced and skilled  radio amateur living nearby who is very helpful. I know that many people think that people with a limited technical knowledge/background should not be in amateur radio I of course would disagree! I try to use these things as learning points although I know I am never going to be skilled in the electronics field although I do enjoy learning.

Digital Mode Samples - v2.0

A very useful little video I found. Thought it was worth sharing.

A dinosaur with a lot to learn

Although I have been in this hobby for around 27 years I still have a lot to learn. Or mybe its just that I haven't kept up with developments! I started thinking this way a couple of days back when I had a PSK QSO with a station on 15 metres. This was a European station, not DX, at the end of the QSO he asked me to "spot him on the cluster". Now I think I know what this means, I am aware of the DX cluster, but I don't use it and I would not have a clue how to "spot" some one.
A Local amateur friend has a Two HF rigs, both conected to the PC and uses the "Ham Radio Deluxe" software. He has the DX cluster on the screen and if he sees an interesting DX station he can just click on the callsign and the rig is automatically tuned to the DX station frequency. I could do this, there are two computers in the schack and my FT1000MP could be computer controlled. Why don't I do this- I'm not sure-maybe I should. Perhaps I am a dinosaur, I still use a paper logbook and sometimes its nice to use the radio without a PC switiched on.

Conditions generally seem to be picking up. I notice that 15 metres and 17 metres are open more now. My 40/80 metre shortened dipole appears to be working fairly well, it also loads up an all bands from 80 metres upwards.
As far as the mobile HF setup is concerned I have been concentrating on 40 metres. Over the past few weeks I have heard many VK and ZL stations on 40 first thing in the morning with good signals. So far I haven't worked any as they always seem to have big pile ups. I have had some inter UK contacts on 40 mobile though and am enjoying the facility of HF when I am driving.

New Microphone

I noticed this base microphone on Ebay about a week ago, its a Yaesu MD-11ABJ. After doing a little bit of research (thanks Google!) I found that it had the same pin outs as my Yaesu FT857. As the price was very reasonable I thought I would give it a try. Its a fairly odd looking piece of kit, I think it was aimed at the PMR market, but it works well enough and I am told the audio from it is quite good. Since I mainly use the FT857 on 2 metres FM at the moment I don't know if the mic would be suitable for SSB work. One odd thing about this Microphone-if you look at the picture there is a "PTT "button, a "Lock" button and a "Monitor" button.
We all know what the PTT does, but if you push the monitor button the rig powers down and  switches off. The "Lock" button is not to lock the PTT it is to lock the "monitor" button down, as if you do not keep the "monitor" down the rig will not stay on. Not a problem of course-but I wonder what the purpose of this was?

My new inverted V dipole seems to work well enough. On 80 metres I have worked several G on SSB with good reports  and into Germany on 80metre PSK with 25 watts. If anything the dipole seems better than my old inverted L, particularly for inter UK on 80. On 40 metres I have heard VK and a couple of stations in the USA it seems quite lively and the background noise is noticeably lower than the end fed inverted L. I still need to get the match on 80 metres sorted out and one leg of the dipole needs to be brought  higher and into the clear.

Dipole

Since I had a days leave from work and the weather was good today I set about making up a 40/80metre shortened dipole using two EL40-XC coils that are intended to allow a half size G5RV to tune on 80 metres.

First impressions are that the antenna works well on 40 metres, maybe not so good on 80 but time will tell, I haven't really had a chance to fully test it. It still needs some work I think and I want to re-position it slightly to get it a little higher. Overall it seems quieter than the end fed inverted L and still tunes from 80-10 metres using the internal ATUs of both my FT1000MP and TS450s

Antenna thoughts

Before winter sets in I am pondering whether to try replacing my Inverted L that I use on 80 and 40 (and 30 metres) with  either a doublet or a dipole. The disadvantage of this is that half of such an antenna would be running through the empty field behind me would not be, as the inverted L is fully contained in my small 10 metres by 10 metres garden. The antenna would have to be supported at its centre in an inverted V style. At an old QTH for a while I used a half size G5RV. It worked fairly well and I even inserted traps and an additional length of wire to allow it to tune up on 80 metres. I didn't have that antenna up for long enough to properly evaluate it, so it may be worth another try.
Long gone are the days when as a young SWL I had a 100 metre long wire, even a 40 metre dipole is too big for my garden!

The Story so far.

I am quite impressed with the way my mobile setup for HF is working. This week I have mainly been monitoring 40 metres on my travels. I have worked into Germany and the Orkney Islands despite 40 not being in such great shape. I also had a contact with a station in Cardiff who was able to give me a very useful audio report as I was driving nearby. It seems I don't have any nasty noises, no RF getting back into the rig or anything like that. I do get some QRN from the car on 40 metres but luckily the noise blanker takes care of it.
When I have been out and about earlier, around 7AM I have heard several VKs and ZLs on 40 at quite good strength, haven't worked them yet though, there always seems to be a pile up!