HSU -- My choice would be to sell the 4X500As and purchase one
Chinese 3-500ZG. If your 3-500Z died from a filament to grid short,
your TL-922 may have intermittently oscillated c. 120MHz. The fix is
to reduce the Q of the VHF suppressors from the original Q of 4.5 to
2 or less. Also, both RFCs can be replaced with a fusing element to
protect against another sudden death. Either a 0.25A 3AG fuse or a
0.25W or 0.5W carbon film resistor will work. 20 to 39 ohms seems to
do okay -- the idea being that a frangible R is easier to blow than
the original 1A choke. To protect each fusing element from 10m RF,
add 1000pF or so to the original 600pF of grid bypass.
cheers
On Jul 23, 2006, at 3:54 AM, Hsu wrote:
> Hi, I'm a new member.My TL922's 3-500Zs died,I have some 4X500As,it
> seems the 3-500Z can convertion by 4X500A, Does anyone have this
> experience?Thanks in advance!
> 73! Hsu
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>
R L MEASURES, AG6K. 805-386-3734
r@somis.org
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