CHAPMAN S6BS

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CHAPMAN S6BS

Postby 6B4G » Tue Mar 31, 2015 10:38 pm

Has anyone seen or worked on a CHAPMAN S6BS?
I was asked to re install the tubes on this unit after someone has
removed them, I can't find any schematics so I'm stuck.
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Re: CHAPMAN S6BS

Postby DeathRex » Wed Apr 01, 2015 7:34 am

I searched and found this:
EF41 RF amplifier
ECH42 Frequency changer
EF41 1st IF
EF41 2nd IF
EBF80 AGC IF, AGC rectifier, Demodulator
And that would be the Mark I version. There was also 3 x EF89, ECH81, EBF80.
It's English, so maybe a English member would be able to find more. Might have to ask at DIYAudio.
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Re: CHAPMAN S6BS

Postby 6B4G » Wed Apr 01, 2015 11:45 am

Thanks Rex this is what I found

Chapman S6BS/FM
Valves: three EF89, ECH81, EM84, EF85, ECF80, two EF80, EB91, EZ80, EBF80. Frequency range: 37-108 Mc/s, 11m, 13m, 16m, 19m, 25m, and 31m in six band spread ranges, 13-43m, 43-140m, 175-570m. Power supply: 110V and 200/250V 50 c/s. Consumption: 65 watts.
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Re: CHAPMAN S6BS

Postby DeathRex » Wed Apr 01, 2015 8:47 pm

Oh dang 12 tubes, you really need a schematic. I checked at radiomuseum, they don't have it either.
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Re: CHAPMAN S6BS

Postby 6B4G » Wed Apr 01, 2015 10:49 pm

The classic part is that all the info we are getting seems to be wrong,
there are only 7 tubes.
GZ80, EBF80, ECH81, EM84, EF89. EF89, and the last one has the markings rubbed off
but it looks like a EF89.
here are some pics.
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Re: CHAPMAN S6BS

Postby 6B4G » Wed Apr 01, 2015 10:50 pm

another one
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Re: CHAPMAN S6BS

Postby 6B4G » Wed Apr 01, 2015 10:52 pm

and the front
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Re: CHAPMAN S6BS

Postby DeathRex » Tue Apr 07, 2015 6:08 pm

Have you made any headway.

It should be kinda easy to find out where most of them go.
The ECH81 is a oscillator/convertor, it should go near the capacitor gang, in one of those two sockets. Since pin8 is the anode for the heptode section, it should goto a transformer in one of the cans. Also since the ECH81 has two anodes, both should have voltage on them if powered up; pins 8 and 6.
The EF89 will also have voltage on pins 7 and 8, where pin 7 will go into a transformer can, and pin 8 will have a small film capacitor on it for filtering. Pins 1 and/or 6 will be grounded.
The EBF80 will be at the end of the IF chain because the diodes are needed for detector/descriminator. It should go to the socket all the way to the left. Pins 6, 7, and 8 should all go into that can beside it.
The GZ80 should be a EZ80, it should goto the bottom socket on the left. Make sure you have 2 smaller wires coming from the transformer to pins 1 and 7. Pin 3 should goto a electrolytic filter capacitor.
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Re: CHAPMAN S6BS

Postby 6B4G » Tue Apr 14, 2015 1:49 am

Hi Rex just got back from the country, I have received the following from http://www.radiomuseum.org/
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Re: CHAPMAN S6BS

Postby DeathRex » Fri Apr 17, 2015 9:15 am

Yep, that's about what I'm thinking.
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