[Boatanchors] Hallicrafters SX-111 ANL Distortion

[Al Klase]

Alan,

I'm not familiar with the SX-111, however the ANL's in 50's/60's 
receivers were a simple clippers designed to beat back automotive 
ignition noise.  They worked well on these short pulses, but in these 
days, where properly suppressed ignition systems are ubiquitous, we 
rarely encounter that sort of noise.  Yes, the ANL will generally 
distort the audio somewhat.  Don't confuse it with a sophisticated noise 
blanker.

Regards,
Al
p
On 8/13/2019 7:13 PM, Alan Gutfrucht wrote:
> 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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-- 
Al Klase – N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/