[hpsdr] Penny PTT unkeying spike - T/R sequencing?

[Tom Cathey]

 Thanks for the info, Dick.

Those 13V amps are generally no cleaner than -28db 3rd IMD.  The usually
don't  publish the IMD specs that I can see, for good reason... :-)  I'm
looking for something with at least -40 db or better.

An interesting idea:  I might try an FT-102 as the linear for Penny. The
Yaesu FT-102 (I have two here) has an internal tube amp that shows -40db 3rd
using -6db of RF negative feedback. I plan to increase that feedback some
more and use only 30 watts output from its 160w capability. There is a point
in the rig that will accept <100Mw.   The hassle would be band changing, but
it would cure the need for band pass filters as well as give a really clean
output that is starting to approach the cleanliness of Penny. (Penny is
closer to -50db 3rd) 

Some may say I am cutting hairs, but to listen to the difference between
-30db 3rd and  -45 to -50db 3rd is quite dramatic. It's all relative, but
the cleaner signal almost disappears right after the filter drops out,
whereas, the dirtier signal persists with crud up another khz or so. 

I'll post my results later. 

Tom, K1JJ



-------------------
You might look at the Tokyo High Power HL-45B information, a design that is
very similar to the  Pennywhistle but provides 45W using a higher power /
different package version [RD30HVF1] in the Mitsubishi family.



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