[Boatanchors] Hallicrafters SX-111 ANL Distortion

[Dale Parfitt]

The ANL is an audio clipper for AM. It is not intended for use on SSB.

-----Original Message-----
From: boatanchors-bounces at mailman.qth.net
[mailto:boatanchors-bounces at mailman.qth.net] On Behalf Of Alan Gutfrucht
Sent: Tuesday, August 13, 2019 7:13 PM
To: hallicrafters at mailman.qth.net; boatanchors at mailman.qth.net
Subject: [Boatanchors] Hallicrafters SX-111 ANL Distortion

Hello,

 

I picked up a SX-111 (Mark I) a while back and finally got it on the bench
for re-capping and alignment. I replaced all the paper capacitors, the power
supply electrolytic and several out of tolerance resistors. 

 

I have an issue with the ANL in that it distorts the audio on SSB reception,
especially with stronger signals. The audio is still intelligible but
nevertheless distorted. Turning the ANL switch off resolves the problem and
the audio sounds good. I have never had or operated an SX-111 before so I
don't know if this behavior is normal for the rig. I have done some reading
and have found reports of distorted audio on the SX-101 which has a similar
ANL circuitry. 

 

I have checked all the tube voltages per the chart in the manual and all are
good except for this particular tube, the 6BJ7 triple diode. Pins 6 and 7,
the ANL cathode and plate both read .22 volts. The chart says I should see
zero volts. I can not find a reason for the difference. 

 

Other than this, the SX-111 seems fine, has good sensitivity and plays well.
Am I seeing something completely normal for the SX-111? Should I leave it be
and move on? Any opinions and/or insight would be greatly appreciated.

 

73, Alan WB2FZC

 

 

 

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