[FLWSS] 222 tube amps and more

Mon Jan 28 10:18:22 EST 2008

rr Sam, am6155 easier  '54 not bad  either  so finally sat down and read stuff on the internet ..read some more ,read some more and got pretty confused and found some contradictory info or huh? part of the mods .. email to kd4esv he got me in touch with Perry over in brooksville who straightened me out  so here we are 8 months later back at it in search of 
more power on 222 to get us into troposcatter ,meteorscatter realm ,i removed the tube tray and had a game plan to keep the mod simple  with caps or less caps.
My reasoning behind the caps were , not to modify the pedestal inductor if possible and find thru experimentation which combination would reach near Zero  reactance (resonant) at 222  if you measure the pedestal inductor it is made for around 115mc  looks to me more like a shorted stub .
The idea was at some point you could find a resonant input or near enough to allow power transfer  crude but all i have to go on without a good scope, anylyser harmonics will work at 111mc but what am i really looking at at the 2nd harmonic below ?  there again the formulas would probably be handy   so my first attempt was a pair of 34pf  close but not quite.. well lets see dug around the junk box 1 54pf bluedevil then another... was thinking more cap would offset negative effects of inductor.. crude .. but carried on ...the thing foremost in my mind was make sure the near 300v grid bias is guarded well from the radio and me!  use good caps..
soldered the 54pf's in place 222 rf  was making to the tube .

 i reconstructed the gridline  entirely on the am6154  ,remove everyything except for the input tuning cap and the varicap on the pedestal inductor,  the grid bias supply left it stock, it has a basic regulator circuit in it,instead of the original voltage divider/zener , back to the grid input ,using a low level 222 input with tube rack removed from the amp chassis ! no power is on the amp at this point .. i got best power transfer /minimum swr with a couple good quality disc caps 1000v,  i used 2- 54pf caps,   1 is tied from the input of the rf input of the grid cavity  to the pedestal inductor , add jumper wire from pedestal inductor to input tuning cap stator side ,solder other 54pf from stator of input tuning cap to grid your done ,tunes fairly broad 
and will take 25w drive now for 350w out. lock the input varicaps for your best input on the  tube rack/tray.
the output  much easier push the plunger in to uhf and and lock in i found my best forward peak around 90 on the counter and have not had to adjust this since. 

Another technique which could be tried (experiment)  to broadband the input by swamping the grid  into a hipower noninductive resistor @ 50 Ω  isolating grid bias with a disc cap around 1200pf at input from rig  you would see 50 ohm resistive at the grid, would take some experimenting which is best cap to use . 
I wish i knew the formulas for matching a tube input as measured  and understood the nomenclature a little better  presently trying to make a real 6m input into a sb200 so far the stuff on the internet hasn't worked i looked through some of my arrl handbooks and didn't see any examples other than for a 3cx800   this tube 50 Ω input so not a good example ..
so  i tried the swamping trick on the sb200 closest i ve got to 6m input yet  

73 ke4wbo

From: kf4yox at embarqmail.comTo: gh6mtr at hotmail.com; kt4ja at cfl.rr.com; Subject: Re: [FLWSS] 222 tube amps and moreDate: Sun, 27 Jan 2008 18:48:01 -0500

Just a note the am6155/54 uses a 8930 with a much higher plate disipation (larger anode). 350-400 watts is not a problem. Also the am6155 is the amp to use on 222 it requires only a very small modification to the input(aside form the other mods needed to get it on the air) The 54 version would be much harder. My 6155 screams on 222 with no problem what so ever.
                                           73 Sam kf4yox

----- Original Message ----- 
From: GRAHAM HULS 
To: Walter Dail K4HV ; flwss at flwss.net 
Sent: Sunday, January 27, 2008 5:22 PM
Subject: Re: [FLWSS] 222 tube amps and more
yep can't disagree there try buying a plate transformer new now with 2 high voltage caps, and diodes,good quality flame proof resistors  etc.  approaching $250+   ..not only that the am6154 amps look cool in the shack, kind of big,heavy, so you need a good stout metal rack or shelves for these things , running one am6154  on 222 now with an easy 320-350w out stock 4cx250b  darn near spec per the eimac manual and just  below power supply ratings,  so just right.The blower a little noisy but it needs air ,so put my cans on and don't even notice   ..  qrv most morning,evening's  qro cw 222090  fsk441 222080 ssb 22100 monitor 24/7 ,4-16el k1fo's looking northwest thru florida or west across the gulf .  i can work Will in el89 250miles away he's often 559-599  73 ke4wbo el96vw > From: kt4ja at cfl.rr.com> To: > Date: Sun, 27 Jan 2008 16:25:54 -0500> Subject: Re: [FLWSS] 222 tube amps and more> > The quickest is to convert a AM-6154 or 6155. They are identical except for> the stock input> circuit. I've bought them for as little as $90. If you try to find one> that's already > converted and has relays, I'd guessimate $350-400 or more. > > I've never seen a 2C39 on anything than 1296. For more power you could use a> 4CX250.> It would be simpler and cheap.> > For the time cost and aggravation a 615X is dirt cheap. You can't buy all> the components> at that price. Not to mention the knowledge base you can draw upon.> > Walter K4HV> > > -----Original Message-----> From: flwss-bounces at flwss.net [mailto:flwss-bounces at flwss.net] On Behalf Of> George Presley> Sent: Sunday, January 27, 2008 3:05 PM> To: FLWSS Bulletin Board> Subject: [FLWSS] 222 tube amps and more> > > Thanks Graham,> > It's good to know that the AM-6154's can also be made to operate on 222. > > Has anyone ever run across anyone using a 2c39 on 222? I ask because I have> a few of them. I'm looking at all my options verses time and cost.> > George K4RSV> > > > _______________________________________________> Website http://www.flwss.net> > FLWSS mailing list> FLWSS at flwss.net http://flwss.net/mailman/listinfo/flwss_flwss.net> > > > _______________________________________________> Website http://www.flwss.net> > FLWSS mailing list> FLWSS at flwss.net> http://flwss.net/mailman/listinfo/flwss_flwss.net

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