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Post by brownbomber72 on Dec 23, 2020 21:20:08 GMT -5
About to purchase a package deal of two Mark II's. I would like to get some opinions on these rigs. Not much out there on the internet about them. Would like to find some service info. The guy I am buying from said one works and the other he does not know about. I think this would be a good one to use to learn how to make repairs on.
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Post by 2600 on Dec 24, 2020 1:16:15 GMT -5
Maybe I should let someone else burst your bubble?
The Mark 2 falls on the wrong side of a line that more-or-less separates the Mark 3 from all the older base stations.
That line has to do with a particular kind of IF transformer called the "K-Tran".
Inside any Browning base radio are tall skinny aluminum 'can' structures with an adjustment hole at the top and bottom. Inside will be one or two tuning coils and a capacitor for each. The newer ones reveal a hollow tuning slug behind that hole with a hexagonal hole about 1/10 inch across.
Before (approximately) 1970 Browning and other factories used a different type called the "K-Tran". It's easy to spot since what appears under the adjustment holes is a screwdriver slot, not a hole of any kind.
Long story short, the internal structure of a K-Tran starts to come apart. Inside are two capacitors made each from a stack of metal plates and thin mica sheets. Spring pressure keeps them pressed tightly together.
The plastic frame inside the K-Tran shrinks and becomes brittle with age. The capacitor plates shift around and the adjustment slug no longer gets you a proper "peak" in the receive signal when it's turned.
Bummer.
Of course it's always possible your radios or one of them hasn't degraded that far yet.
Yet.
Bear in mind that the transmitter uses one crystal for each transmit channel. An external VFO to fit that transmitter is not an easy item to track down. This quirk applies to most AM-only transmitters that use one crystal per channel. The Mark 3 SSB transmitter is VFO-friendly, but the AM-only transmitters not so much.
Have fun and 73!
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Post by brownbomber72 on Dec 24, 2020 20:24:14 GMT -5
I have heard of the K-Tran problems. I hit it lucky with a R2700 I picked up not long ago as far as it not having any issues so I hope that luck holds out. Talked to the guy I am getting them from a few hours ago and he is also throwing in a Mark I or Golden Eagle (I am not sure of the proper name lol) for a few extra bucks. He talked to me on the air on it and it sounded great.
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Post by 2600 on Dec 25, 2020 0:25:03 GMT -5
Very cool! Low mileage always works in your favor.
73
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