EH Scott Radio Enthusiasts

The Fine Things are Always Hand Made

McMurdo Silver Maserpiece V filter chokes

One of the filter chokes in my Masterpiece V has started buzzing loudly. I've tried tightening the screws, shimming the winding and dipping the choke in wax all with little success so my thought is to have the choke rewound. 

Does anyone know where I would find:

1. Where I would find the value of the MP5's filter chokes?

2. Who would perform this type of service?

3. Would it make sense to have both filter chokes rewound even though only one is currently acting up?

Thanks,

-Tony

Views: 70

Comment by Dave on June 17, 2019 at 10:03am

Have you found answers to your questions Tony, I have similar situation with my MP6.

Comment by Tony Peterson on June 17, 2019 at 11:27am

No Dave. No luck so far. The radio's currently on "the back burner". If I do find anything out I'll post it here.

Comment by Dave on June 18, 2019 at 8:56am

Our friend Gerry Steffens would know, I have not heard from him.

Comment by Kent King on June 18, 2019 at 12:34pm

Gerry has had some health issues and hasn't been online much in the past year or so. 

The filter choke is going to be pretty hefty...if we compare to a similar Scott, we have a 10H and a 30H choke in the power supply. Measure the resistance of the buzzing choke. For reference, the Scott 10H choke is 50 ohms, and the 30H choke runs about 150 ohms...so you can get a really good estimate based on the DC resistance. 

As for rewinding, I don't know who is doing that work anymore, I'd ask on the Antique Radio Forum (or search there). I would not rewind a working unit, the buzzing is a fairly unusual issue, fixing that unit alone should be sufficient.

Kent

Comment by Robert Feenstra on June 18, 2019 at 8:06pm

You might try Heyboer Transformer in Grand Haven, MIchigan.  It would be pricey I'm sure.  You can always do it yourself.  It's not that hard.  I've done several output transformers and a power transformer.

www.heyboertransformers.com

Comment by Scott Seickel on June 18, 2019 at 9:38pm
Comment by Tony Peterson on June 19, 2019 at 1:37pm

Thanks for the tips. As soon as I get the Patterson that I'm working on now off the bench I'm going to follow Kent's suggestion then contact Heyboer. Any ideas what the current rating should be?

Comment by David C. Poland on June 19, 2019 at 4:21pm

From MS photos, the MS chokes look a lot like Scott chokes. Might be your alternative at a reasonable cost. From all my Scotts over the years, never had a choke buzz like you describe.

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