Hi Marco,

It's always something, isn't it?

I am very happy to get this new PA working well. I was (and will be)
running it at less than half the power it is capable of, so
hopefully it will live a long time. :-)

I never did figure out what the original problem was. I took the PA
apart to try using some of the cores in other tests, and when I put
it back together it worked! I did use a different group of FETs, so...

More recently I made a new output transformer, this time with the 20
turn secondary split into four sections with 5 turns each, spaces
between. This allows the primary winding to be closer to the core
(it fits better into the spaces between groups of secondary turns),
which seems to produce good results and better drain waveform.

But, both my LF receive converter (10 - 300 kHz) and auxiliary
receiver (TS-930S 100 kHz and up) have died so now I can only
receive in and very near LF and MF ham bands. More work to do...

73,
Paul N1BUG



On 07/29/2018 11:14 AM, [email protected] wrote:
> Hi Paul,
> 
> nice to read that you din't give up! :-)
> Hopefully for the good season also from this side will be ready;-)
> Just when the new MF PA was ready, functioning and able to push
> enough juice to reach the 1W limit the exciter decided to stop :-((
> Probably I had to be more patient and attempting to re-sold a TSSOIC
> IC I ruined the PCB.. I mounted it some years ago with a better
> sight.. so I had to start not a simple IC replacing but prepare a
> new PCB for the IC (with P'nP sheet I had to do several attemp to
> prepare the PCB and again place a new IC but finally I succeed ).
> Now the exciter is functioning fine alone and with the LF PAs, but
> on MF there is apparently a carrier residual (leakage through the
> FST3253) which is too high so I'm getting RF output also with no
> modulation..
> so more to do..
> 
> 73 Marco, IK1HSS