KLH 21

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KLH 21

Post by willy3486 on Tue Oct 21, 2014 8:32 am

I am looking at a KLH 21 for a friend. The radio was playing but then died. The amps seems fine and I can tune in one station. I am thinking something on the tuning board has died. There is one transistor that when you touch it kills the station signal I get.

My problem is the tuner board has a shield all over it and a top cover that snaps on. I have looked at the original 21 service floating on the web and it has a different tuner board. This board has no shield in the manual and the layout is different. But the other boards look to be the same otherwise. Does anyone know of a service manual where the tuning cap board is shielded completely?

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Re: KLH 21

Post by 75X11 on Tue Oct 21, 2014 4:51 pm

I did some searching to see if I could see an illustration of any variations. The only variant I saw mentioned was a 21 model II. Might that be it?

http://www.radiomuseum.org/r/klh_klh_twenty_one_21ii.html
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Re: KLH 21

Post by willy3486 on Tue Oct 21, 2014 5:15 pm

I am not sure. From what I have found is that there is one made in about 65 that is almost like the one I have. It has the same amp and another board with most of the fm circuitry on it. But the actual tuning cap board is different from the one I have. I also found a 21 diagram that looks to be from the mid 70s. It has ICs on that one so I know its not the one I have. I would love to see the actual diagram for this tuning board but the one I have is the only proof I can find they ever existed. What I am thinking about doing is to unsolder all the solder connections that go through the shielding then take the shielding off and resolder it so I can do some troubleshooting. This guy is into the 60s and above stuff so he gives me all the old stuff he finds. So I want to get it going.

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Re: KLH 21

Post by 75X11 on Tue Oct 21, 2014 5:49 pm

Hate to see you have to do the unsoldering, but sometimes one must do what one must. Did yours have the pillow inside it? Maybe the shielding was to prevent the batting from getting into the more sensitive works.
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Re: KLH 21

Post by willy3486 on Tue Oct 21, 2014 8:32 pm

Yes , it had the fiberglass bag. I am wondering one of two things. One is if this is the second version of the radio thus adding the shielding and changing the tuning part or the other this was a replacement board for some reason. Maybe a aftermarket upgrade or a repair under warranty.

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Re: KLH 21

Post by 75X11 on Tue Oct 21, 2014 9:44 pm

I can understand shielding being a good choice for a performance upgrade. Some solid state units were subject to microphonics and various means were undertaken to supress them.
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Re: KLH 21

Post by willy3486 on Fri Oct 24, 2014 1:50 am

I got it going! I thought I would post what I did. I made a quick diagram of the 7 pins out of the cage. I also labeled which wire went to which pin and also where the two resistors were wired in. I took it apart and it was a pain. I then put jumper wires to it and wired it up, still no station. I did a cross reference and came up with a RF signal npn. I didn't have that but I did have one similar so I tried it. I couldn't even pick up the one station. I then pulled that one out and put the original in. To my surprise it worked perfect.

I got to looking and it had a few bad solder joints. So after heating and soldering them better it works great. So hopefully this one is finished. I will let it play a hour or so to test it. This has worked out great for both of us. He also has a amp he needs a few RCA jacks put on instead of the plug it has. so an hour or so with that and I am finished. He had a box of nice tubes I can use and some other junk I can use but he doesn't . So I can trade the repair and get much needed parts.

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Re: KLH 21

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