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Old 17th Feb 2018, 8:13 pm   #1
coopzone
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Default Replacing an EM80 with 6E2 (EM87) in an Ekco VHF radio

Hello everyone,

My latest radio arrived a couple of days ago, an Ekco A277. It's a bit of a mess, so it should keep me happy for days!

The Magic eye, as expected, did not work (among other things), an EM80. I know other people seem to be able to find these cheap, but I can't, nothing under £8.00+£5.00 postage. I did have a later model (got it weeks ago for only £3.00 free postage and its NOS). So I decided I'd use that instead of the original.

See attached Before, and after circuits attached. And you may want to double check my pin numbering on the valves - just to be safe.

Steps,

1, remove old EM80 and unsolder the fly leads to the base.
2, replace R11 with 1 1m5 - 1m8 meg resister. This compensates for the difference between g1 control voltage.
3, remove the 470k resistor R14 from the valve base.
4, add the new 120K resistor between pins 9 and 6.
5, connect pin 6 to 250v supply in fly leads.
6, connect pin 3 and pin4 (heater) to the yellow GND wire.
7, connect pin 7 to pin 9
8, connect pin 5 to green (6.3v, heater) wire.

Job done see last photo.
Attached Thumbnails
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Old 17th Feb 2018, 8:35 pm   #2
Philips210
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Default Re: Replacing an EM80 with 6E2 (em87) in an Ekco VHF radio

Hi.

That's a great result and thanks for sharing the details of the mod. The EM87 was often used in Grundig reel to reel tape recorders and seems to last quite well compared to the EM80.

Regards
Symon
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Old 28th Mar 2018, 6:11 pm   #3
coopzone
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Default Re: Replacing an EM80 with 6E2 (em87) in an Ekco VHF radio

I have since revised this mod, having seen more examples of em87/em84 in use. The 120k resistor should be 470k. The 120k will shorten the lifetime of the valve.
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