>
>
>
>>> 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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