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Author Topic: Drake TR-4 S Meter  (Read 4539 times)
G0FGJ
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Posts: 5




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« on: November 11, 2013, 12:36:50 AM »

I have a Drake TR4 which has not been powered since 1991.  Thought I would get it back on the air so;

Cleaned all the switch contacts with a high temperature contact cleaner.

Replaced the old paper caps with a heath## shop kit. Tadge expensive by the time I payed import duty, but the quality of the dc is now much improved.

So powered up the radio....nothing no audio at all although the S meter did seem to indicate the odd signal. V17 looked a little dim so replaced the valve....still nothing.  Tested again the PSU all was fine and then found on one power up I got audio. Appeared the PSU plug was not making good connection so more lube (WD40) this time as no other contact cleaner to hand.

So now left with a semi working radio with two faults:

1) the radio is very crackly with some quiet periods and then some periods of electrical noise being picked up.

2) The S meter is reading a steady signal strength of 5.

Would be interested in any recommendations on how to proceed.  Thinking it may be worth trying contact cleaner again on all the valve bases. As for the S meter have yet to look at the circuit so open to suggestions.
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K5RT
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Posts: 155




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« Reply #1 on: November 11, 2013, 03:30:54 AM »

Is the noise blanker plug installed?
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G0FGJ
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Posts: 5




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« Reply #2 on: November 11, 2013, 07:51:12 AM »

Don't think there is a noise blanker plug on the TR-4, is there?

Me thinks it more likely to be poor connection on a valve base so have been looking at how to clean them.
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AD4U
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Posts: 2173




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« Reply #3 on: November 11, 2013, 08:55:49 AM »

Don't think there is a noise blanker plug on the TR-4, is there?

Me thinks it more likely to be poor connection on a valve base so have been looking at how to clean them.

Remove each valve one at a time.  Spray DeOxit into the valve socket. While the valve socket it still wet with DeOxit, "wiggle" the valve while reinserting it into the socket.  Repeat for each of the 20 valves.

Dick  AD4U
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G0FGJ
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Posts: 5




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« Reply #4 on: November 11, 2013, 09:42:32 AM »

Thanks Dick

Did find the culprit valve by going around each one and given them a nudge. Whilst now free of crackles the radio appears deaf although the antenna is just a 12 inch wire! Will look on flea bay for Deoxit but think is does not come cheap over here in the UK.

Will also get a longer antenna connected tomorrow before I proceed as difficult to make any assessment of the Rx.

Andy
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WB8PFZ
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Posts: 81




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« Reply #5 on: November 14, 2013, 08:20:35 AM »

WD40?HuhHuhHuh??
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G0FGJ
Member

Posts: 5




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« Reply #6 on: November 14, 2013, 10:47:46 AM »

Went through all the tube bases and cleaned each using IPA. Rx is now quiet without an antenna but when one is connected the background noise is horrendous!

20m appears to be dead. Would this suggest a crystal fault? 

Tempted to do a full alignment first though before I get the soldering iron out or invest in more tubes.
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G0FGJ
Member

Posts: 5




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« Reply #7 on: November 17, 2013, 12:31:50 AM »

Out of interest has anyone found cleaning the crystal sockets improves the radio sensitivity?
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