emud: Rekord Senior 60--HELP!!!

Hello all...

I'm currently working on an Emud Rekord Senior 60 (export model) and need some assitance. I've replaced the known bad/weak tubes, replaced the 3 electrolytic filter capacitors and all of the paper capacitors, and the is radio close to being electronically restored.

However, I am having a problem with the AM/SW section of the radio. FM band works fine, lots of frequency response, nice and crisp, however the frequency alignment is off about 1mHz. The problem is that both the AM & SW bands are very very low in terms of volume. Sensitivity is also not very good, as it will only pickup the local stations and even has trouble doing that. Antenna seems to be connected okay. Anybody have an idea as to if this is a tube problem or something else? I'm thinking it could be a tube though I'm not sure which one, as I wasn't able to check them all with my tester (didn't have tube data for 2 of them). I'm stumped on this one. Any help would be GREATLY appreciated!

Thanks!

John
 

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Check to see how the radio operates with another ECH81

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Hi Omer...

Thanks for your response!  I've already replaced the ECH81, as the original was weak.  That didn't work.  Do you have any other ideas?

Thanks again!

John

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Not looking at the schematic, check your resistors!

You should also go back, and check your connections and placement of the capacitors, as well as solder joints.

In addition, clean contacts on switches with Deoxit cleaner and then Deoxit Gold.

I'm not sure if these radios suffer from silver mica disease.

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Hi John,

do you have the possibility of checking the IF transformers (460 KHz bandpass filters)?

Since the AM bands are weak, at least one 460 KHz circuit may be out of resonance. This is the 1st step: check the IF section.

You will need an oscilloscope and a RF signal generator. Feed the RF to the 1st grid of the ECH81(not necessary to unsolder anything, just connect to the pin.). Check the value of the voltage beginnig from the diode of EABC80 via EF89 (anode and grid) back to the anode of the ECH81. Reduce the amplitude of the generator as far as possible in order not to activate agc. 

If a resonance circuit is out of order, unsufficient amplification or an extra damping will result. 

More comfortable was the use of a wobbler for IF. The resonance curves could be seen directly, and aligning the IF filters is easy.

EMUD radios seem to be very similar, even if they have different valves, see e.g. the "Funkberater".

Best regards,

Dietmar

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