[AMPS] Misc. Oscillations

[measures]

>
>
>
>>> Adjusting filament-v is simpler than tuning a tank.  Several models of
>>> Henry Radio amplifiers use approx. 6v on 3-500Z/8008 (4.8v) filaments. 
>>> How safe is that, Mr Subich?
>>
>>
>>3-500Z's have 5 volt filaments, not 4.8. Your twisting of numbers 
>>reminds me of the national budget!
>>
>>
>>73, Tom W8JI
>>w8ji@contesting.com
>
>Tom,
>
>Actually the Eimac 3-500Z brochure states the filament voltage is 5.0V +/-
>0.25V.  By that definition, 4.75V should also provide full emission.
>However, operating the filament at less than 5.0V, will certainly increase
>tube life (also per Eimac).  The math is easy...  I operate my modified
>TL-922s with approximately 4.8V on the filaments.
>
>73 Tom,
>
>de Don
>
>>I have a TL-922, one day it went boom when I was using it.  The band switch
>>vaporized...yes vaporized.  People told me I must have done it due to poor
>>op practices.  So, $80 bux later..I installed the new band switch.
>
>Jerry, 
>I also had this happen to me. The 80m tap had completely vanished.  I
>replaced the switch, but then modified the amp.  I have also personally sent
>two bandswitches to other (DL) TL-922 owners.  This amp eats bandswithes!
> 
Indeed, Don.  One way to stop a TL-922 from dining on bandswitches is to 
reduce the plate spacing in the 6000v Tune-C.  The first rotor plate is 
uniformly bent so that the cap breaks down at 4000v for any C setting.  
Since the normal anode potential in the 922 tank is c. 2900v peak, a 
4000v Tune-cap is plenty - yet if need be it will arc over first and 
protect the more delicate bandswitch.   note - A high-pot. is useful for 
performing this task.  


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