john <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Garey,
This has been my experience as well (in multiple Drake transmitters).
John K5MO
At 02:13 PM 11/8/2007, Garey Barrell wrote:
Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Ron -
The 6GJ5 is the ONE substitute that I have found to work just fine in all
the four series transmitters. It is an _identical_ tube to the 6JB6
with the single exception of the suppressor grid being tied internally to
the cathode in the GJ, while the suppressor grid is brought out to Pin 8
in the JB. Pin 8 is hardwired to ground in all the Drake transmitters,
while the cathode is at RF ground and DC ground via the 2 ohm meter shunt
resistor. Since the Drake transmitters are Class AB1, grounded cathode
finals, there is absolutely no effect on operation of the final
stages. The same caveats about brands apply, i.e., some brands will NOT
neutralize without modification, but otherwise the GJ works just fine.
73, Garey - K4OAH
St Charles, IL
Drake 2-B, 4-B & C-Line Service Supplement CDs
<www.k4oah.com>
[EMAIL PROTECTED] wrote:
If the statement below is correct, that may be part of the problem.
The TR4 having 6GJ5 transmit tubes could be your first real
problem. The transceiver uses the 6JB6 tube for final tubes, or the 12
volt version in the very old TR4's and TR3's. There is a tendency
because of cost and availability to use like replacement tubes, but doing
so brings other problems to the table. I have experimented with
several "so-called" 6JB6 replacement tubes, and have found there are no
replacement tubes. Granted some substitutes work better than others
but none performed well across all the bands as compared to using the
6JB6 tube.
Many of the side effects of using substitute tubes include erratic
tuning, max output not at resonant plate current dip, neutralization
issues on the higher bands, filament string current unbalance, and the
list goes on and on. The bottom line the substitute tubes will give
you problems, and typically they get worse the higher in frequency you go.
If your pulling out your hair fighting a problem like this, just make
sure the problem is not being generated by using the wrong tube.
Ron Baker / WB4HFN
-------------- Original message --------------
From: [EMAIL PROTECTED]
To the group & all who offered assistance I did get it to load up
about 1:30 AM this morning
Garey Barrell <[EMAIL PROTECTED]>
Hi Garey, Yep all of the filiments on the 6GJ5's were working as
I advised, and you accepted as fact.
Did get to the problem, my procedures and the antenna relay.
Two clean out rounds later with the antenna relay got it (it had
already had one) ...had to do a bit of tweaking too. Open frame,
little plastic cover that clips on RF choke in the way, and I
noted it needed a new SO239 so it got a lot of things done.
Right now output is about 120 W but I am probably doing it
wrong. Gotta find a local Elmer with Drake experience to go
through the tune up procedures with me..until I can get it
correct. "Beverages offered"
Carl Hibbard WD8NHK (Dayton, OH)
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