GM3WOJ - ZL1CT Amplifiers page                                 Updated November 2006


Since 1978, on the long, cold, windy, dark nights of a typical Scottish winter, I've enjoyed building linear amplifiers - some HF, some VHF - about 12 in total - here are photos of most of these amplifiers.

Click on any of these thumbnail pictures to see the full-size picture - these are .jpg files - up to 220kB.

This HF amp. in the photos below was built in 1992 (1 x 4CX1500B) 

      GREEN21.jpg (209600 bytes)                  HF


This HF amp. in the photos below was built in 1994 (1 x 4CX1500B)

      Henley2.jpg (317144 bytes)      HENLEY21.jpg (205639 bytes)           HF

This amp. was named 'Henley' because the front panel is painted with 'Henley Blue' colour paint, but of course it's a childish play on words !


These 2 pictures below are the only evidence that an amplifier called 'B29' ever existed - I dismantled it in Jan.2001 because it was taking up too much space!  Using 2 x 4-400A's, it was intended as a 'slave' amplifier, powered by another amp's PSU.  The 'B29' name came from the fact that the front panel was 0.25" thick plate !

B291.jpg (75445 bytes)     B292.jpg (84976 bytes)         HF


This HF amp. in the photo below was built in 1980 (1 x QY5-500)   It produces a lot of noise and heat !

BERTHA1.jpg (208640 bytes)            HF

This amp. is on loan to my friend Stewart GM4AFF for the GM0F contest station.


This HF amp. in the photo below was built in 1996.   It produces a lot of RF !

CP1.jpg (210205 bytes)            HF

This amp. is so noisy that I've had to mount the blower in the loft (attic) with ducting to carry the cold air down (this has the advantage that the blower is always drawing in cold air, except in mid-summer)   Someone asked if I was 'Aeronautical mobile' before I moved the blower !


This 50MHz amp. in the photo below was built in 2000 (1 x 8877) - see

887721.jpg (203020 bytes)             VHF


This 70MHz amp. in the photo below was built in 1978 (2 x 4CX250B)     It's sitting on top of an N7ART (2 x 3CX800A7) 432MHz amp. which belongs to Jim GM4TXX.

70MHZ1.jpg (211255 bytes)              VHF


This 50MHz amp. in the photo below was built in 1984 (2 x 4CX250B)

50MHZ1.jpg (210641 bytes)               VHF

This 'old banger' (literally at times) has worked 151 DXCC countries for me on 6m !  It's only failed once - in 2002 I  heard XU7ABW and was about to call him when one of the HV smoothing capacitors went open-circuit, and the power output dropped to about 150W of hum-ridden SSB, so no QSO with XU7, but I worked XW, VR and BY a few days later


This is the first commercial amp. I've ever owned - the small but useful Ameritron AL-80 (1 x 3-500ZG) - purchased in 1999.    

 AL801.jpg (213529 bytes)           HF

This early-model AL-80 had very poor cooling - the original fan draws air in, then filters it before it leaves the cabinet i.e. the filter would become clogged with dust on the inside.  I reversed the original fan to make it blow cold air directly onto the valve seals, and fitted an extra fan above the valve, which extracts air, which in turn cools the PSU, etc.


In 2001 I bought an Alpha 91B, also for my contest expeditions and DXpeditions. (The picture below is of the newer Alpha 99 model, which looks vaguely similar)

    a_alpha99sm3.jpg (8933 bytes)   Alpha 99 - visit       HF


In 2003 I was given an RF generator, made by the Japanese company Anelva, which had been used as a Plasma generator in the semiconductor industry, running on 13.56MHz. Two turns of the Tune and Load capacitors and we were on 14MHz !!

ProjectZ-2.jpg (271310 bytes)          HF

The 3-phase Japanese power supply and control circuitry have been completely rebuilt and I've fitted Jennings vacuum RF c/o relays.


In May 1998 I started work on a surplus unit known only as Project X. There are numerous technical challenges to be overcome, but I am working slowly on this exciting project, which I hope to finish this decade !         HF


GM3WOJ and ZL1CT shack motto          

 In my teens it was QQV03-10's

In my twenties it was QQV06-40A's

In my thirties it was 4CX250B's

In my forties it was 4CX1500B's

In my fifties it is 8171.jpg (208109 bytes)  

(this motto is surprisingly accurate !)