[Drake] TR4C unwanted carrier

[D C *Mac* Macdonald]

Does this occur in BOTH sideband modes?
The Drake stuff uses (IIRC) just one
"carrier" crystal and switches filters
for sideband choice.  The placement of
the 9.000 MHz crystal MUST be dead center
or there is likely to be carrier leakage
on one or the other sideband.  Carrier
suppression in filter style exciters is
relies on both the balanced modulator AND
proper positioning of the carrier signal
down the slopes of the filters.

* * * * * * * * * * *
* 73 - Mac, K2GKK/5 *
* (Since 30 Nov 53) *
* Oklahoma City, OK *
* USAF, Ret (61-81) *
* * * * * * * * * * *
 


> From: kf4nsradio at verizon.net
> To: drake at mailman.qth.net
> Date: Tue, 8 Feb 2011 16:09:15 -0500
> Subject: [Drake] TR4C unwanted carrier
> 
> Hi Guys,
> This is a repost of the one I sent over the holidays. Must have been a 
> bad time to send it. Got no replies.
> 
> "I just had my first lengthy QSO on 20M SSB since the restoration. A
> problem has popped up that was not an apparent trouble while doing all
> the testing on the bench.
> 
> After about a full minute of transmission the wattmeter starts showing
> a gradual climbing of carrier on the SSB signal. I have very good air
> flow, carrier balance was set during rehab, the finals were
> neutralized. Power output is over 200W with plate current reading
> around 500ma.
> 
> This does sound like a heat problem but as I said, there is plenty of
> air flow in and out of the rig. I have not tried lowering the output
> yet to see what that does but just wanted to put this to the groups
> ASAP before I do any damage. I know that one of the filters is bad but
> the 9mhz OSC. was tweaked with C130 to a satisfactory balance which
> left the CXR OSC still very close to 9MHZ. Let me know your thoughts."
> 
> 73, Dick KF4NS
> St Petersburg, FL 33714 USA
> 
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