Are 813's suitable for HF SSB?

kd4e doc at KD4E.COM
Thu Feb 26 10:39:43 EST 2009

>  I had fb results, with a pair of parallel triode connected 813s, in
>  GG, on SSB, but never used them above 14 Mhz. IIRC, there was an
>  article in HR magazine, describing an amp. that used a trio of 813s
>  in the triode connected GG configuration. However, if you want good
>  efficiency at 21 Mhz, or above, the GS-35 should yield superior
>  results. 73 de Ron n4gjv

OK re. that.  The designs to which I linked seem to solve lots of the
21MHz and above challenges as well as some efficiency challenges.
We live in the woods so 160M and even 6M are not problems.

The GS-35B seems to want some pretty heavy plate current - my HV
PS source would not be able to supply that.  I can get to 4,400v 300ma
or 2400v 600ma or some other mix of HV & current in and around that.

I gather that a 3-500Z has better gain so I'd get more output for the same
HV & current.  I gather that the 3-500Z also performs better at higher
frequencies - but they are also much more costly.

 >  Well, the pair that I used for years, G-G, for a full kw on ssb, cw, 
 > for rtty, seemed to work just fine.. I did replace them once... but 
that wasn't
 > because they had a fault.. more like air leakage.. sudden like... 
when they
 > had something dropped on them. but that is a story for another time. But
 > the only thing that the amp had a problem with was getting the filament
 > choke in place to hold the current without getting too hot.
 > Past that, they worked fine.. and the choke only had to be mounted 
 > then it was fine too.
 > They did like a fair amount of free air.. and yes, I drove them, but 
then I kept
 > threatening to replace them with a pair of 4-400s if they didn't work 
for their
 > supper. They did.
 > Used a pole pig for the HV, with a pair of solid diode stacks from a 
 > station tx, that didn't need them any longer. The caps were stacked 
and balanced
 > with r's and bypassed with little c's. I didn't use mine on 160.. but 
that wasn't for
 > lack of want to... more a case of don't dare... too close to too many 
folks.. besides
 > the 21 mc if tv next door was having a tuff time dealing with my 
driver.. much
 > less the amp... with the antenna only 35 - 40 feet away...
 >  I could look out my window, watch the tv for the most distortion as 
I tuned up...
 > worked great as a remote field strength meter...
  as long as I didn't try that during "As the World Turns" .. the lady 
of the house
 > didn't bother me... and the fellow there was at work.. so .. they 
didn't need to
 > buy a new tv.. as long as I remembered when the show was on.
 > --... ...-- Dale - WC7S in Wy

Interesting remote-located tuning monitor!  ;-)

No access to a pole-pig here - but I think I have found the HV PS I need.

813's seem to run about $30. each, or at least that is the cheapest 
price I have
found so far.


Thanks! & 73, doc, KD4E
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