Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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George -
OK, if you have the tone, then the likely culprits are C98 (part of the
Twist-Lok electrolytic) which is quite possibly bad by now, leaky C99 or
CR16, or maybe a low bias supply voltage, although that usually shows
first as an inability to set Final idle current. C107, the "other" side
of the Twist-Lok cap can also be a culprit, usually showing as a
"backwave" on CW, i.e., tone not shut off completely between code elements.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B & C-Line Service Supplement CDs
<www.k4oah.com>
George Runyan wrote:
"George Runyan" <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Thanks Gary. I think you have pointed me in the right direction. I have a
tone until the carrier drops out. I had swapped the 12AX7's but no fix.
I will look deeper into the circuit.
Best Regards,
George
WB6YEC
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Garey Barrell
Sent: Friday, August 17, 2007 7:21 PM
To: [EMAIL PROTECTED]
Subject: Re: [drakelist] C line question
Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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George -
Check to make sure the DELAY pots are set to mid-range, and that the VOX
gain is turned "up" enough. ANTI-VOX can also cause this if set too
high. IF this is all correct, you might have a tone oscillator not running.
The tone oscillator (phase shift network around the mic amp [12AX7]) may
not be running. The "speed-up" network for CW (CR17, C115, R107) pulls
the carrier in momentarily, but drops out almost immediately because the
tone isn't there. If it's not, you won't have any sidetone either...
Try swapping the 12AX7 V9. If you don't have a spare, just swap with V1
to check. The tone is generated in V9a, amplified in V9b, V1A and V10a,
then rectified by CR16, integrated in C99 to turn on V10b to close the
relay.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B & C-Line Service Supplement CDs
<www.k4oah.com>
George Runyan wrote:
I have a C line that will not show me the output in the tune position.
Momentarily shows output in CW. Puts out nicely in SSB when speech
applied.
I tried the 6FQ7 and adjusting VOX. I pulled the relay and cleaned
with card stock. Any help? Thanks for the help.
George
WB6YEC
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