To owners of SB-1000s and AL-80s: :
The B+ to gnd bypass cap. (C-23 in SB1000) at the base of the HV RFC
(RFC-3) is 1000pF. At 1.8MHz, 1000pF has -j88 ohms of reactance. It is
my opinion that 88 ohms is not a sufficient bypass. My unsolicited
advise is to:
1. parallel more C with C23 to keep RF away from PS components during
160m and 80m operation.
2. add a glitch protection resistor in the B+ lead.
3. add 200a-pk glitch diodes to protect the meter movements.
4. disregard the users' manual's ok of more than 500mA of anode current.
No 3-500Z/8008 manufacturer has Ever rated this tube at more than 400mA.
Might not the designer improve his credibility if he corrected his
misstatement?.
good luck.
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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