"Jason Buchanan" <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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If you peak the RF Tune and immediately dip the PLATE control, then
"two-hand" the PLATE and LOAD controls for maximum output power, (using an
external wattmeter, holding down that meter switch button makes it a LOT
more difficult,) and then DIP the PLATE control as the last adjustment,
(which shouldn't be required if the transmitter is properly neutralized,
but should be done anyway,) finals will last for 5-10 years of "normal"
amateur use. I have a T-4XB and T-4XC that have been running for over 10
years with the same finals. Both are used several times a week, primarily
on CW.
Sounds like it is absolutely imperative that the 6JB6's be neutralized as
best as possible. Mine aren't producing maximum output at the bottom of the
dip. When I replace T-4XB R26 I will make sure they are neutralized as good
as I can. Right now I have to rotate the plate control a wee bit CW for max
output. But the bottom of the dip vs. max output is about a needle's width
so I don't feel too bad about it.
Is it necessary to neutralize the finals at 28.500 or can I do this on 15 or
20 into a resonant antenna?
By the way, a small fan on the receiver certainly won't hurt anything, (as
long as it is quiet!,) but as noted above, three units ran 24/7 for 8-9
years with no fans, and NO failures. I turn my receivers on in the
morning, and turn them off when I am through for the day. I have known
guys who turn their receiver off when they leave the room for lunch!! NOT
a recipe for long life of electronic equipment.
When my parents bought the B line I have now I used to turn it on and leave
it on for days (no drift!), plus it looked cool hi. I did that for years
until I was out of high school and they were shut off for 15 years until I
got married, bought a house and put an antenna up at the new QTH. I
remember reading somewhere that a day's worth of useful filament life is
consumed by simply turning the rig on, so I leave them on unless I know i'm
not going to use them for another 24 hours. Most of the tubes in this B
line are the same ones that it came with from the factory in 1971. I
replaced the 6EH5 because it started sounding nasty but I suspect that it's
actually the filter cap.
I noticed the other day that there is a mustard yellow Sprague ATOM
electrolytic can tied from the R-4B power supply board to chassis ground,
and I noticed there is a guy selling these exact parts on an auction site
listed as a fix for faulty electrolytics - does this sound familiar? I was
thinking about replacing the R-4B filter can with the kit from WA9TGT but
i'm wondering what kind of work I need to "un-do" to use this cap
replacement kit.....
73 Jason N1SU
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