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Old 8th Mar 2021, 7:17 pm   #19
ChristianFletcher
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Join Date: Dec 2003
Location: South Yorkshire, UK.
Posts: 900
Default Re: Hallicrafters S20-R Sky Champion.

I was working on the S20-R this weekend and I now have the radio making it’s own sound. I have installed a mult-tapped output transformer from RS components and this has matched well with the speaker and the radio sounds ok for me. The electrical specifications for the transformer list primarily current as 40ma and I am measuring 35mA of current through the transformer. The data sheet doesn’t specify if the primary current is a nominal value or a maximum. Would it be worth increasing the valve of the cathode bypass resistor to further reduce the current

I have also replaced much of the damaged power supply wiring and sorted the shorting local oscillator tuning gang problem.

I don’t the the AVC is operating correctly at the moment as the set appears to be overloading but the rf gain control does the trick when the AVC is switched off. Also have no BFO at the moment and was going to tackle those next.

More good news is that the band select switch does work on all bands even though it feels rough. I did a quick check on each band it works but big variation in sensitivity

Anyone interested can see the work going on here https://youtu.be/eGspnbj2PE8

Thanks regards Chris
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