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Old 7th Nov 2017, 3:37 pm   #6
russell_w_b
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Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
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Default Re: Converted GPO 332 (mk1) receiver EXTREMELY quiet, help!

Quote:
Originally Posted by DrBagPhD View Post
'.. so I suppose that means there's something wrong with the 332 internals?'
You need to look at the 'dial off-normal' contacts on the dial. Looking at yours, both sets of contacts look to be closed, and they should be open when the dial is at rest. You see that little cam on the dial centre behind the big central nut? It should be pushing those contacts open and letting them close when the dial is turned. It needs adjusted slightly so that the insulated bit on the point of the cam is holding the contacts open.

The function of these contacts is to short out the receiver when dialling so you don't get loud clicks (one set of contacts), and to make a CR circuit across the dial pulse contacts to quench arcing and to prevent distortion of the dialling pulse (the other set). If these contacts are closed when the dial is at rest, your receiver will be shorted out.

I see your instrument has a 'slipping cam' dial on it (Dial No:10). If you look here, there's a good bit about setting it up. But if you wish to prove this, insert a sliver of insulating material between the 'off normal' contacts (not the pulse contacts!) and see if the volume increases.
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