SOTABEAMS Speech Compressor

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A new addition to my shack…

I have used my Yaesu FT857D and FT450D for years now, but have found that working stations in pile ups and noise is frustrating. My voice is fairly quiet and I have to ‘talk-up’ the microphone in order to work stations in contests. The modern Yaesu transceivers seem to lack a good speech processor. When I saw the SOTABEAMS Speech Compressor Kit advertised I realised that this is what I need. I ordered one and built the kit, which is very easy to build and set up. Now I have the ‘talk power’ to get through the noise, reports from stations are excellent and it really makes a difference!
Although the Speech Compressor is really meant for the FT817, it works really well with both the FT857D and FT450D.


Yaesu G-450c Rotator

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After the storm…

After one failed attempt to get the aerials down, I got in touch with my friendly aerial rigger to come and have a look. Even though the weather was still atrocious, they went up their ladders and brought my aerials down safely. They will come back later to put the aerials back up again. When the weather eased and became sunny again I spent some time cleaning up the aerials and greasing all the fittings with Vaseline. I decided to fit my new (very expensive) Yaesu G-450c rotator to the stack of aerials. When I had everything ready I sent a text message to my riggers and they came an hour later to erect the new set up. New heavy duty K and T brackets along with scaffold quality pole fitted and now I have a nice new rotator and aerials that are much higher than before.


Storm Eleanor

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My aerials have survived many storms over the years, but not this one!

Yesterday I opened the curtains to find that my aerial stack had come crashing down. The aerials were hanging by the wires, so they didn’t hit the ground, but had fallen in an awkward place making it hard to get down. The wind was still howling and rain lashing it down, so imposible to do anything until today.
A phone call to the local aerial rigger was needed and I am so thankful that he came out in the awful weather and brought the aerials down safely without any damage.
Now I will spend the next few days cleaning up the aerials ready to be put back up again.



Happy Christmas!

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Oh that silly Elf trying out my AT5!

Codar AT5 completed project!

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This has been an enjoyable and nostalgic project.  My vision was to have a rebuilt Codar AT5 and Power Supply working fine on Topband AM, just like the old days. My biggest problem was the power supply, it is not easy to find components to give an output of a 300v, 150v and 6.3v. After an appeal on Facebook and Packet Radio, Dave G4JLG came up with a suitable transformer. I went to see Dave and he showed me around his shack, his antennas are impressive to say the least! Next I needed a suitable aluminium case to house the PSU and transformer. I had an old 12v PSU case that I didn’t want any more, so I stripped it down and used the case, just the job. One problem that I had was the smoothing choke, I found one on e-bay which was ideal as well as a nice 32mf / 32mf 500v smoothing capacitor.  The PSU also has the switching for the AT5, so I bought a suitable 4 pole 3 way switch and PL239 sockets for the antenna feeds. The OA2 stabiliser valve and socket I got from the Rochdale Rally. I added a couple of indicator bulbs (actually LEDs) to show NET and TX, these are powered from an extra 6.3v winding on the transformer.

The completed Power Supply and case.

Now for the Codar AT5 itself, I didn’t want to try to power up the transmitter without doing some renovating. The inside of the transmitter is in very good condition, some of the old resistors had already been replaced. The 160m / 80m switch had fallen to pieces as well as the AF gain potentiometer, so these needed replacing which I did without any problem. A couple of high power resistors also needed changing and I tested all the other components with my test meter. Now the big problem…on the back of the AT5 is a B9A socket which provides the power to the transmitter. I needed a B9A plug to connect the PSU to the Codar AT5. They stopped making these years ago and nobody stocks them when you look on line including e-bay. Another appeal on Facebook was needed, this time helped by Malcolm G3ZNU who kindly sent me one. Now I was ready to power up this little beast and see what it can do!

It works fine! Now got an HT voltage of 250v on load from the power supply and giving a carrier output of 7 watts. The AM modulation seems to be working and sounds ok, but I need some reports now to see what it really sounds like. Last night I came on the Topband Bolton Wireless Club 1.953Mhz net and got reports from Dave, G4JLG, Ian G0CTO, John G4NTY and Geoff G4DZK. Nice reports, audio sounds fine, but modulation level a bit low. The audio gain is turned right up, so I decided to investigate the problem. I looked at the circuit diagram and realised that there are two 10mf decoupling capacitors in the cathodes of the audio stage. I don’t remember seeing any small electrolytics when I was rebuilding parts of the transmitter, I had a look and sure enough, hidden beneath the wiring were two old electrolytic capacitors. I changed them and tested the AT5 again, WOW! what a difference, the modulation level shot up, so much that I had to back off the audio gain control. Fantastic!

My vision…just like the old days, including the Acos Microphone!

Rochdale Rally Nov. 2017

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This time I went to this rally with a list of bits that I wanted, mainly for my Codar AT5 and Power Supply that I am building. Parts are becoming difficult to find now. I needed an OA2 stabiliser valve and B7G valve base, a B9A plug to connect to the AT5, some 2 or 3 watt resistors, grommets, rubber feet, and other bits and pieces.  Amazingly, I managed to get all except the B9A plug!

I really enjoyed this rally, lots of second hand stuff and junk to sift through, but this one was different…I have never seen so many morse keys in all my life!  There seemed to be morse keys of one sort or another at most of the stands, but one stand had literally scores of various keys…CW Heaven! Also an abundant number of Z-Matches, you can see at least three in the first photo.

I’m surprised that nobody bought the Stolle Rotator in this photo. I had one on the chimney for over 25 years and it was a brilliant rotator cost me £15. I have just bought a Yaesu rotator and it cost almost £300!

Acos Microphone

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To go with the Codar AT5 I need a high impedance crystal microphone.
Eventually, I found my old favourite Acos Microphone on e-bay!
My original one that I used with my old topband transmitter was grey, the audio quality was superb. I used it for years until one day I left it hanging on my anglepoise lamp. The heat destroyed it!
I looked around for ages to find a replacement, then one day I passed a second hand shop in Radcliffe and there in the window was an Acos microphone. The shop was closed, so I asked my then girlfriend (now wife) to buy it for me. She did.  It was black rather than grey, identical to the one I bought on e-bay last week.