Have been working on the TR7 CW issue and today I changed the
switching transistor that turns on the 10 volts and off. Before I
changed the PNP transistor when the key is up it showed 1.77 volts
and now it shows 0.8 volts but that seems to be enough to keep the
crystal oscillator running. Got to think this over more and try
something else. Any idea and or suggestions welcomed.
73, Jim VE1RB
On 2025-02-01 16:33, Jim Harris via
groups.io wrote:
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Thanks Jim for the info and I will try and get
back at it tomorrow.?
73, Jim VE1RB
Yes, you want to look at the 2nd IF/Audio board. CW
operation is described towards the end of the text in
section 2-11 of the service manual. In short the CW transmit
carrier is generated by a crystal oscillator that is offset
nominally 800 Hz from the dial frequency. The oscillator is
keyed by Q1103 on this board.
More info on the oscillator is here:
On Sat, 1 Feb 2025 14:17:50 -0400
"Jim Harris via "
<radiove1rb=[email protected]>
wrote:
> Hi once again. I am back trouble shooting the TR7 with
what I hope is the
> last problem. When I switch the mode switch to CW I get
a 1800 cycle tone
> in the receiver that is over S9 in strength. If you
change the frequency
> this tone does not change at all. I have a Version 2,
2nd I.F/Audio board.
> I have not found an explanation of how the CW operation
works but maybe the
> problem is on that board. Anyone got any ideas? All
suggestions appreciated
> and welcomed.
> Thank you, Jim VE1RB
--
73
-Jim
NU0C
