>>>Rich wrote:
>>>
>>>>? In my opinion, due to use of heat-resistant spring material, the best
>>>>sockets made for the 3-500Z were those used in the Trio-Kenwood TL-922.
>>>>Replacements may still may be available from Kenwood parts. My best
>>>>3-500Z cooling system award goes to Heath for the split-chassis design
>>>>used in the SB-220.
>>>
>>>There is a number of people on this side of the pond who would disagree.
>>>TL922s are prone to socket problems.
>>
>>? Specifically?
>>
>Specifically, inadequate cooling, resulting in degradation of the clips,
>producing I2R losses, leading to a vicious circle. As a consequence the
>sockets need replacing and the tube pins need resoldering.
>
? Did you see this for yourself? // I too had doubts about the cooling
in my TL-922, so I operated it upside down with the bottom cover resting
in place. After about a minute of operation, I popped off the bottom
cover and used my thumb to evaluate the temperature of the (critical)
filament pins, 1 and 5. The amount of heat did not cause discomfort in
my temperature evaluator. . . If a 922 owner experienced solder
melting in 3-500Z filament pins, I would want to know about how much
clearance existed at the rear of the amplifier where the hot air exits.
Another possible cause of cooling probs is failure to inject 0.02cc of 5w
- 10w oil through the neoprene seal on the fan bearing chamber every 5 or
so years of operation -- which is one of the reasons that we include a
fan-oiling syringe with our vhf suppressor retrofit kits.
(note -- to cool itself properly, the rear of 922 needs about one meter
of vertical clearance, and about 0.2m of horiz. and side clearances.
The 922 should not be placed under a shelf or in an equipment console. .
>Transverse airflow is seldom sufficient adequately to cool the tube pins.
? Transverse air cooling seems to work ok in motorcycle engines. Does
vertical airflow make sense when the anode-connector's cooling fins run
horizontally? // Have you Personally evaluated the filament pin temp.
in a SB-220 and TL-922? . . On the other hand, the filament pin temp.
in an "Eimac air-system" cooled amp. like the Henry 3K-A gets real
"toasty".
- cheers, Chris
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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