Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Hi Boyd -
OK. I can see where your situation could cause a problem. I took Carl
at his word that the filaments were lit, but if he missed one of the PA
tubes it could work out that way. I'll let him know, we are working off
reflector to resolve his problem. A voltage check would show if
something flaky like that was going on.
I have published service supplement CDs for the Drake 4 Line separates
and the 2-B, and have been working on one for the TR-4 series for the
last year. Each CD includes ALL the variations of the schematics. So
far I have eleven different schematics for the TR-4 series, Bill Frost
at Drake only has two! There were several in the area of your serial
number, and I'm away from home this week, so I don't have them all with me.
Obvious question on your PTO problem, do you have approx 11V on the DC
line of the PTO? There is a 10V Zener inside the PTO that can short,
taking out the 100 ohm decoupling resistor. If you do, can you hear the
PTO running, or see it on a scope if you have access to one. Should be
about 1.25-2V p-p output. IF the PTO is "dead", the transistor, or FET,
can be replaced without affecting the linearity. I'll be back home next
week and can get you the correct schematic for your s/n.
I hope the CD will be ready later this month, but it keeps stretching
out as I find more variations, necessitating more photos!
73, Garey - K4OAH
St Charles, IL
Drake 2-B, 4-B & C-Line Service Supplement CDs
<www.k4oah.com>
Boyd Van Horn wrote:
Garey, The reason i mentioned the final filaments is I found one set
with only one of the filaments not working . It allowed the receiver
to function, but not quite up to par. You seem to be very knowledgable
on these, so I have a problem maybe you can help me with. I have an
eary TR4- SN 23470. The on board PTO will not function, but the
external vfo will function fine. It has the 3 section filter cap
instead of 4 like the later models and a bunch of stand up component
boards unlike the later ones. What do you normally find wrong in that
situation ? I have fulled out the PTO and the circuit if different
than my schematic. It only has one diode instead of two and the
components are located in different places. Any help would be
appreciated. Boyd W0BUW
*/Garey Barrell <[EMAIL PROTECTED]>/* wrote:
Garey Barrell made an utterance to the drakelist gang
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The final filaments are in series with most of the receiver tube
filaments, so if the receiver is working, that is not the problem.
The bias supply should be variable from approx -45 to -85V. The
screens
should have approximately 250 VDC, current limited to less in
X-CW. The
plate voltage is 650 VDC. IF these voltages are present, and the
cathodes are grounded through the 15 ohm cathode resistors, you
should
be able to adjust the bias for the 0.1A idle current. The system
is the
same as the T-4XC, just one more tube. Same rules.
73, Garey - K4OAH
Boyd Van Horn wrote:
> Carl, Check the filaments on the finals. They are all three in
> parallel and drop the 12.6 volts to 6.3 for the remainder of the
> tubes. The wires to the filaments are small and brittle. Measure
the
> Bias voltage coming out of the power supply- should be at least -65
> and you should be able to reduce it to zero. When you go to X-CW
you
> should have 350 volts on the final screens and when you go to
ssb the
> voltage should go to 650 volts. Be Careful !!! Also the sealed
> transmit /receive relays are known to go bad. If you need one
you can
> order from Mouser in Texas- the manufacturers part number is
> R10-EIY4-V2.5K. Good Luck, Boyd
>
> */Garey Barrell /* wrote:
>
>
> Garey Barrell made an utterance to the drakelist gang
>
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> Carl -
>
> No. No modifications are necessary to use the 6GJ5. Pin 8 is no
> connection in the 6GJ5, and is the suppressor grid on the 6JB6,
> which is
> grounded.
>
> You say NO plate current. Do you have bias current?
>
> Garey - K4OAH
> St Charles, IL
>
> [EMAIL PROTECTED] wrote:
> > [EMAIL PROTECTED] writes:
> > abbreviated excerpt below
> >
> > The 6GJ5's will work fine....... Garey - K4OAH
> >
> > Hi, TR4 will not tune up...no plate current...have been advised
> that
> > 6GJ5's may have to have pin 8 cut off.
> > Your thoughts.
> > Carl Hibbard WD8NHK
> >
>
>
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