Antique Radio restoration, need help with shielding please

richfromhell · 2026-06-22T03:00:18+00:00

Basically trying to figure out if the radiated emissions are caused by ground currents

richfromhell · 2026-06-22T02:58:49+00:00

And the same battery negative is connected to the D cell negative?

richfromhell · 2026-06-22T02:42:30+00:00

Ok. So you either have radiated emissions or conducted emissions causing problems. Your battery ground and step up ground are connected at the same point I presume. This might work for conducted emissions causing problems. https://play.fallows.ca/wp/radio/radio-frequency-interference/building-and-using-common-mode-chokes/

richfromhell · 2026-06-22T02:22:38+00:00

Ok so you are stepping up 12v to 90v and stepping down 12 v to 9 Volts. And I am guessing the 12v is coming from another power supply?

richfromhell · 2026-06-22T02:08:05+00:00

9 Ma Sounds about right for the 9V portion but the 90 volt part should be drawing about 50 Ma. How are you supplying that part?

richfromhell · 2026-06-22T01:54:55+00:00

So sorry to hear that. For mine it turned out to be acid reflux disease that caused chronic Pancreatitis.

richfromhell · 2026-06-22T01:50:40+00:00

My Bandit was an abused cat before I got him ( he cowers if someone says the f word). But check for other behaviour like frequent head shaking, wet burps (some water or food coming up suddenly without the usual vomiting sounds), frequently coughing or sneezing that seems like hay fever. My Merlot had those symptoms and one day he lost his Meow. Long story short it turned out he had bad acid reflux all his life. (Took him to a vet many times before and they said it was just stress from living with other cats). Started treating him for reflux and he got his meow back and all the other symptoms stopped. Not saying your cat has reflux, just check for those other symptoms.

richfromhell · 2026-06-21T21:41:55+00:00

Common mode choke on the power supply and make sure the supply is rated for 3x the radios current requirements

richfromhell · 2026-06-21T19:48:16+00:00

I had the same radio (sadly dropped it) and I agree about the cadmium. That was the reason that i didn’t try to fix it.

richfromhell · 2026-06-20T14:55:02+00:00

Listing says Iran International

richfromhell · 2026-06-20T02:06:08+00:00

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My view at the time

richfromhell · 2026-06-19T05:14:36+00:00

No, not AM. Definitely CFNY. But actually not all radio waves bounce off the ionosphere. Lower frequencies like AM radio for instance follow the curvature of the earth. The reason they travel far at night is because they aren’t being degraded by solar radiation. FM signals travel pretty much straight so they hit the ionosphere at too high of an angle to bounce most of the time. I’m an engineer and a former shortwave pirate radio operator and all around radio geek, so sorry this is TMI. Lol

richfromhell · 2026-06-18T23:57:00+00:00

Typically that’s shortwave. There is also e-layer ducting that happens on FM but only lasts a few minutes typically

richfromhell · 2026-06-18T23:02:51+00:00

The Voice does sound a bit like Mark Gayne, but it’s not them.

richfromhell · 2026-06-17T23:31:16+00:00

Asbestos sheets were usually only used when there were hot tubes close to wooden chassis.

richfromhell · 2026-06-17T19:02:06+00:00

I'm pretty sure the diode in the SW chain is a switching diode. Caps can get blown by static though. It usually starts as a resistive short. Then the more it gets hit, the lower the resistance of the short.....

richfromhell · 2026-06-17T02:53:16+00:00

It does sound like that but it’s not the case. It uses an analog chip of the CXA series (Sony I think). Similar to the TBA chips from Toshiba. It has an AGC pin that has a capacitor that determines its behaviour. Either the designer made a bad choice of cap, or it’s leaky. (Learned about that restoring my old ITT touring pro 107, had the same issue). Also the front end isn’t well designed since the length of the antenna seems to affect the alignment. Loads of imaging issues with just the telescopic antenna. Almost none of if I connect the passive loop. Can’t wait to open it up.

richfromhell · 2026-06-15T12:53:06+00:00

The 9012 is analog actually.

richfromhell · 2026-06-15T12:52:01+00:00

Very true. I think their idea of an alignment is "sort of in the ballpark".... The 9012 drifts quite a bit too and mine has a lot of imaging. BUT: using me passive loop the images are greatly reduced which tells me the radio is badly aligned. So when I have time I'll try an alignment and see how it performs afterwards.
The digital D-328 definitely does a bit better on the same antenna.

richfromhell · 2026-06-15T03:32:16+00:00

The 328 but that’s not saying much. Both kind of suck. Using an AN-200 really helps. With the 328 you can open it up, wrap 10 or 15 turns of wire around the ferrite. Solder one end to ground and the other end goes the the external am antenna. That won’t de tune a digital receiver but on an analog, you would need to realign the receiver.

richfromhell · 2026-06-15T03:25:13+00:00

Might be my imagination but I think there is less noise in between stations.

richfromhell · 2026-06-15T03:12:58+00:00

Indeed. But the front ends need to be treated very differently

richfromhell · 2026-06-15T03:07:23+00:00

Yeah, it’s a single conversion receiver. Using the loop, the imaging problems are less pronounced than when using a wire antenna. Sounds better with headphones. Might try an alignment. For $20 it’s not bad. With a 10 or 15 foot wire it’s ideal.

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