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Sets, Parts and Service Information Wanted (private buyers only, no swaps) If you need help obtaining components, sets or equipment, post a message here. Private buyers only - no traders. No swaps.

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Old 11th Jul 2019, 3:11 pm   #1
cathoderay57
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Join Date: Oct 2017
Location: Bristol, UK.
Posts: 587
Default Wanted: Small HT choke

Hello folks, I'm repairing a Vidor CN350 radio and the HT choke is O/C. I will put a resistor in for the time being but thought it was worth posting a request in case anybody has a suitable replacement. See photo. The mounting holes are 2.5 inches (63mm) apart and it is 40mm tall. According to the Trader Sheet its dc resistance is 390 Ohms and the total HT is a shade over 60mA. Happy to pay a sensible price. Cheers, Jerry
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Old 11th Jul 2019, 3:51 pm   #2
Ed_Dinning
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Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 5,567
Default Re: Wanted: Small HT choke

Hi Jerry, I think there used to be an RS "min smoothing choke" available. It is quite a bit smaller than the normal chokes found in mains sets.

Ed
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Old 11th Jul 2019, 5:19 pm   #3
cathoderay57
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Default Re: Wanted: Small HT choke

Thanks Ed, I found some Hammond and Triad Magnetic chokes from a couple of suppliers that appear suitable; however, apart from a 50mA device which is too low-rated, they are all on back order with an inflated surcharge. I'll hang slack a few days and see if anybody comes up trumps. Cheers, Jerry
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Old 11th Jul 2019, 9:05 pm   #4
cathoderay57
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Default Re: Wanted: Small HT choke

I got the model number wrong - It's a CN359. I see another one is being worked on the Forum! Cheers, Jerry
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Old 12th Jul 2019, 5:36 pm   #5
John_BS
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Location: Wincanton, Somerset, UK.
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Default Re: Wanted: Small HT choke

Jerry:


The failure is often located at a lead-out joint, so it might be worth carfully cutting off the outer insulation to see if it's the end-termination (or last layer). Nothing to lose?

John
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Old 13th Jul 2019, 2:14 pm   #6
cathoderay57
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Join Date: Oct 2017
Location: Bristol, UK.
Posts: 587
Default Re: Wanted: Small HT choke

Hi John, thanks for the tip. I carefully cut back the insulation and got to the point where the solder tag wires are joined to the ends of the coil. Unfortunately the joints are sound and so the problem must be somewhere inside the bobbin. Cheers, Jerry
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Old 13th Jul 2019, 8:34 pm   #7
cathoderay57
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Join Date: Oct 2017
Location: Bristol, UK.
Posts: 587
Default Re: Wanted: Small HT choke

I've tested the radio with a 350R ceramic resistor in place of the choke. Hum level is virtually nil, and the radio works extremely well. I have also just bought a choke off eBay which should do the job but if not then I'll leave the resistor in situ. Mods please close this request. Cheers, Jerry
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