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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
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24th Jun 2018, 10:40 am | #1 |
Hexode
Join Date: Jul 2010
Location: Ireleth-in-Furness, Cumbria, UK.
Posts: 286
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MCR-1 Aerial Trimmer
I got around to trying to sort out the Aerial trimmer on my MCR-1. The shaft of the trimmer was very loose and the vanes touched each other.
Upon inspection the radio must have suffered a bang at some time (maybe other than in the 1940's ), as a part of the knob was loose inside the set. The loose shaft was caused by the sprung earth connection being distorted. I tried to sort things out and with my hamfistedness have only made things worse,the vanes of the rotor and stator have now parted company with the shafts they were crimped on to. I feel the only action is to replace the trimmer capacitor now. I've not seen these trimmer capacitors, before any ideas what other equipment used them, to look out for. Any ideas how to get the shaft nut off, the insulating washer has done a fine job of locking the nut on and due to other components in the area I cannot get a spanner on it. The Cap is 15pf, the shaft is 4mm diameter and 30mm long. |
24th Jun 2018, 10:42 am | #2 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,289
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Re: MCR-1 Aerial Trimmer
Use a long reach thin walled socket on the nut?
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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
24th Jun 2018, 10:48 am | #3 |
Hexode
Join Date: Jul 2010
Location: Ireleth-in-Furness, Cumbria, UK.
Posts: 286
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Re: MCR-1 Aerial Trimmer
Thanks, yes, sound obvious, but once you see the set, that is not possible without removing a "PCB" that the shaft goes through.
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24th Jun 2018, 11:07 am | #4 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: MCR-1 Aerial Trimmer
If all else fails, plus gas or whatever then soldering iron heat on the nut as best as possible then use an old small screw driver with a sharp blade (to use like a small mini chisel) sharp tap on the nut edge anticlockwise just before a hex point, once seal's broken use longnose pliers in the tenth of a turn at a time shuffle mode, should come off ok. Done a few, a bit like cracking large nut/screw interface with a cold chisel on old vehicles etc.
Lawrence. |
24th Jun 2018, 5:45 pm | #5 | |
Hexode
Join Date: Aug 2005
Location: Cheshire, UK.
Posts: 263
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Re: MCR-1 Aerial Trimmer
Quote:
Mike |
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24th Jun 2018, 7:31 pm | #6 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 14,005
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Re: MCR-1 Aerial Trimmer
A 'box spanner' [which is basically a tube with the end formed into a shape to fit the nut] is what you want here.
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24th Jun 2018, 9:54 pm | #7 |
Hexode
Join Date: Jul 2010
Location: Ireleth-in-Furness, Cumbria, UK.
Posts: 286
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Re: MCR-1 Aerial Trimmer
Thanks for the input guys, I particularly like the idea of an open ring spanner. I'll see if I can source the correct part for the job.
Nick |
2nd Jul 2018, 1:09 pm | #8 | |
Hexode
Join Date: Jul 2010
Location: Ireleth-in-Furness, Cumbria, UK.
Posts: 286
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Re: MCR-1 Aerial Trimmer
Quote:
Nothing is easy with this project though, the mounting boss on the trimmer just span around and the lock nut would not come off. I removed the capacitor shaft and fitted a screw extractor in the hole left and finally managed to get it all removed. Now to see if my local metal turning hobbyist can devise a way of joining the 4mm shaft to the 6mm one. Nick |
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18th Jul 2018, 7:46 pm | #9 |
Hexode
Join Date: Jul 2010
Location: Ireleth-in-Furness, Cumbria, UK.
Posts: 286
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Re: MCR-1 Aerial Trimmer
All working well now, I got a model maker to turn a 6mm shaft extender down to 4mm to take the original knob.
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