[AMPS] Blown TL922A... What to do?

[dcckc]

Tom wrote;
>Exactly. Let me tell you what I've been doing the past few months.
>I put a 1200Z7 in an RF deck of the AL1200, and with multiple
>fingerstock contacts the tube was totally stable with no
>suppression at all. That allowed me to add inductance between the
>tube and the tank, to reduce Q on ten meters and bring efficiency
>way up. The only reason that works is because the Z7 has virtually
>zero grid impedance to the chassis. A 1200A7 will oscillate like
>crazy with no suppression, or with suppression and that series coil.
>
>
>I did the same to a 3CX800A7. I added a grid collet instead of a few
>fingers on the grid, and I could remove all suppression on a
>3CX800. That let me use the same technique to put an AL-800
>amp on six meters (bandswitched from 160-6 meters) and get 1200
>watts out on six meters!
>
>
>I have a 3CPX800A7 with 3000 volts on the anode, no suppression,
>a VHF Q of over 1000 in the tank system, and it is completely
>stable. That PA runs 1100 watts out on 2 meters with 30 watts of
>drive, and is rock stable. The reason? The grids are very well
>grounded both inside and outside the tube. The grid "problem" is far
>above the operating frequency so stability isn't an issue.

Its sounds like you have found the an answer to what I thought was a 
imaginary problem if what you say is true and I dont doubt that it is then 
I would hope these improvements would be on the very next  series of 
Ameritron  amps, the word would soon spread about the improvements. Market 
share would no doubt increase and Rich's customer base would dwindle. A 
simple kit could be devised for the adventurous ham or factory up grades 
could be done for minimal cost  or free ala Ruger Arms. the debate would be 
moot and of no  interest . I don't say these things sarcastically,  as  a 
consumer I dont take spending 1000.00 to 3000.00 dollars on anything 
lightly and when I do I expect it to be plug and play not  the parts list 
for my next science experiment in RF design. If there are simple design 
changes that eliminate these problems that have been discussed ad infinitum 
then they should be incorporated no matter who is right or wrong about the 
cause of these problems. Then the debates could focus on the best  designs 
to build homebrew amps and not repair and redesign store bought 
equipment   that shouldn't even need the covers off for several years. This 
is not meant to be an indictment of  Ameritron only   a review of the 
archives leaves no manufacture untouched the kenwood 922 as a recent 
example. I for one am very interested in the info that you have garnered on 
the 1200Z7 I am putting together the makings of a RF deck using two of 
these tubes.

sincerely
Dave / WB0PKK

   


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