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Old 9th Jul 2018, 9:45 am   #1
Alf Fisher
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Default Amplion ADP2

Hi all,
Yesterday at RWB I bought this battery portable radio for a very modest sum for an adventure into sets I haven't previously worked on.

The service data sheet shows it having four 1.4 volt octal based valves:
1A7GT, 1N5GT, 1H5GT and a 3Q5GT. This radio is unusual in that the first 3 valves have been replaced with functionally equivalent B7G types.

It looks like a professional job with paxolin adaptor plates that are fixed to the chassis with rubber grommets to minimise any microphonic effects. The plates are held by nice flat headed bolts and the valve bases are riveted into the paxolin.

Has anyone seen this before and is it an official factory mod ?

Alf
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Old 9th Jul 2018, 10:08 am   #2
crackle
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Default Re: Amplion ADP2

Some photos would be nice.
Mike
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Old 9th Jul 2018, 1:39 pm   #3
Herald1360
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Default Re: Amplion ADP2

I can't see why anyone would want to do this after production. The original type valves would not have been unavailable even if some accident had taken out the filaments on several of them at once (the only reason I can think of for multiple valve replacements}.

There are two versions in RM- one with American types and the other with Osram types so a third with miniature types doesn't seem unlikely. Maybe there was a cost saving even using extra grommets and adaptor plates.
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Old 9th Jul 2018, 9:37 pm   #4
Biggles
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Default Re: Amplion ADP2

I have one of these sets and it has the octal series battery valves fitted as per the service sheet. I can't think of a reason for modifying it in the way yours is. The performance is good enough with the original valve line up and as has been said before, they are readily available. Maybe you have a factory prototype where they were planning on updating the design to use more modern valves?
Alan.

Last edited by Biggles; 9th Jul 2018 at 9:38 pm. Reason: typo
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Old 10th Jul 2018, 5:55 pm   #5
Alf Fisher
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Default Re: Amplion ADP2

Thanks guys for your comments.
I took a couple of pictures to show the valve mounts for V2 and V3. V1 is the same. The photos were a bit big and have been re-sized by the system on here. It all looks like original manufacturers wiring under the chassis so I don't think its a mod the has been done by a repair shop or a previous owner.

Alf
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Old 11th Jul 2018, 8:35 pm   #6
Biggles
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Default Re: Amplion ADP2

I suppose one reason for this modification would be to reduce LT battery current, but this would have to use the "96" series B7G valves with 25mA filaments as opposed to the "91/92/94" types with 50mA filaments, which would amount to the same filament current as the octal range. It's a puzzle.
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Old 11th Jul 2018, 10:35 pm   #7
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Default Re: Amplion ADP2

It could have still been in production when the earlier types went from current to maintenance status.
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Old 12th Jul 2018, 8:12 am   #8
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Default Re: Amplion ADP2

This was very common around 1948 when the new B7G valves replaced the octals. Examples can be seen in early post war Vidor and Ever Ready C models. John.
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