[Drake] T-4XB--no output

[fkamp at comcast.net]

Paul Ellis wrote:
> 
> Hi, all--
> 
> Thanks again to all who helped me troubleshoot my R-4B a few weeks
> back.  Once I got that buttoned together, I started turning my attention to
> my T-4XB, which isn't working right.   The problem is that there's no
> output from the transmitter on the wattmeter.
> 
> I first suspected a bad driver tube and/or finals, so all three tubes had
> known good tubes substituted.  Voltages check out from both the power
> supply (bias is correctly set at -62V) and the filament fuse is just fine.
> Voltages seem to check out at each of the pins of  V4, V5 and V6, too.


You did not mention anything about plate current.  Is there any plate
current?  Can you dip the finals?

Now, before you try that I would suggest removing the RF cage and
inspecting the parts before doing any more tests under power.

Clearances inside the cage are pretty close.  Make sure nothing is
shorting to ground and that everything is mechanically solid.  Nothing
broken or flopping around.  Use an ohm meter and check all the points of
HV and RF to make sure there are no shorts.  Check the plate RF choke to
see if it is open.  Make sure the output capacitor is good (not open or
shorted).

Then do the same under the chassis for the drive circuitry.

Connect the ohm meter across the loading capacitor and tune it through
its range to see if there are any shorts.

Check the transmit relay coil and contacts.  If the relay does not
close, there will be no Rf output.

You might also check the wattmeter to make sure it is working properly.

>From your description it sounds like the driver may be okay.

Regards,
Frank Kamp