[NLRS] CSVHFS article by WA5TNY

[tosca005 at umn.edu]

Thanks for the several kind offers, everyone. Paul Husby already beat all 
of you to it by sending me a PDF that he made from a scan of the article. 
MANY thanks to Paul!

I reallized that some of you may be wondering what I'm up to.

My 5760 transverter is an old DEMI low-power model. I think it's only 200
mW out, but I haven't had a chance to test it. I did pick up the "cut-off
board" (the part that Steve was cutting off the full-power board to make 
the low-power model) and, importantly, the parts needed to build it. The 
cut-off board from DEMI provides a lower-noise preamp and around 1-3 watts 
of power (I forget the details), but haven't had a chance to build that 
either. I am SO looking forward to my imminent retirement! One of the 
WA5TNY boards would still be a significant step up in power, if the IMFETs 
could be found.

A newer article refers to the older article, but he tested a variety of
IMFETs including the use of the 8 watt part to make 30 watts or so.

  http://vk3nx.com/files/5760_MHz_SSPA.pdf

I was under the impression that "only" 4 IMFETs were used, but the newer 
article does not show the circuit or board layout, but mainly the results 
with several different devices. I guess the 5th IMFET was included if you 
didn't have enough power to drive the four 3-watt devices fully. I think 
they have around 9 or 10 dB of gain, so each one probably needs 300 mW for 
full drive.

Not knowing how easy it would be to get the IMFETs or at what cost, I asked 
for a price quote from a source on the Internet for a LOWER frequency part 
that is actually rated for 5760 MHz. They gave me no price figure, but 
simply said they have no stock. I guess I need to look harder if I want to 
pursue this. But if I can successfully build the DEMI cutoff board, I 
should be up to a more reasonable power level. And I actually have a couple 
of the Avantek amplifiers that should each provide 6-10 watts once I build 
a new switching power supply to provide the needed voltages from from +12v 
instead of -14v or -28v.

I was actually thinking about K0MHC's request for a smaller amp than the 
Avantek, and then got interested in it for myself. If I could find the 8 
watt IMFETs for the WA5TNY board as mentioned by VK3NX, I'd probably have 
more power on the band than nearly anyone else in our area! Toshiba used to 
make 35, 45, and 60 watt versions of the IMFET chip. Probably rarer than 
hen's teeth and priced like pure gold, but a guy can dream, right. Besides, 
the chip dimensions on those big boys are bigger, so that would also mean a 
new board design.

Anyway, LOTS of things to keep me busy once I retire!!!  :)

73 de W0JT