Adrian -
Changing the pots to multiturn will have NO effect upon the synthesizer
operation. Again, it doesn't hurt, but isn't _necessary_ for proper
operation.
You definitely have a synthesizer problem, either in the VCOs or the
reference frequencies.
Verify that you have the 500 kHz reference, and then check for the 500
kHz input from the divider chain.
Jim's suggestion to check the 24 VDC supply is a good one. A common
cause of failure is the top "half" of the DC-DC converter transformer
core falls off, or just becomes separated enough to cause the voltage to
drop. Looking at the "top" of the transformer on the Power Supply board
(one with the pots), you should see a solid bar. If you see three
"ends" of an "E" sticking up, look for the top half of the "E" shaped
core in the bottom of the case. If gone, replacements can be had from
Charlie, K3ICH.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs
<www.k4oah.com>
Adrian Rees (MW1LCR) wrote:
Hello all
I have the Service Manual and have it printed out.
To confirm the symptoms, on 21 and 28MHz the counter settles around
33.030MHz and 17.206MHz on all other bands. Connecting an antenna I can
"hear" my signal generator on thes frequencies (sweeping the generator
through the 33 and 17MHz frequencies). With an external source the counter
works fine.
So the synthesizer doesn't appear to be locking. I have cleaned the Molex
connectors. My next course of action is to replace the pots on the voltage
control board for multiturn ones, and re-align the voltages etc, and then
re-check the synthesizer board again.
Thanks all for the help, so far !
Adrian MW1LCR
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