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 Post subject: National Type RCF Receiver info needed
PostPosted: Jun Tue 09, 2009 1:18 am 
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Location: Canyon Lake, TX
I have a National Type RCF "Airway Communication Receiver" in my shop for repair. It looks like it is based on the National NC-100, but has significant differences. Does anyone have a schematic for the RCF or know of a source for one? Any information would be appreciated. This RCF has been modified and the owner would like it restored to its original configuration. --Ed

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PostPosted: Jun Tue 09, 2009 1:30 am 
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Are you sure that isn't RCP, rather than RCF ?? It might make a difference in your search results.

-Chuck


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PostPosted: Jun Tue 09, 2009 1:35 am 
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This might be of help or add to the confusion Ed.

http://amfone.net/Amforum/index.php?topic=8409.0

I never could figure out all those RCx designations. I have another variant made for the Canadian National Railways

Carl


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PostPosted: Jun Tue 09, 2009 2:34 am 
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Somewhere in the archives I have an RCK manual.

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PostPosted: Jun Tue 09, 2009 3:31 am 
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N7RHU wrote:
Are you sure that isn't RCP, rather than RCF ?? It might make a difference in your search results.
-Chuck

It is definitely labeled RCF.

The link that Carl provided does refer to the RCF (and the NC-100F that appears to be similar, but not identical). No schematic available though. --Ed

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PostPosted: Jun Wed 10, 2009 12:29 am 
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They're all pretty much the same as a NC-100 except they have an extra toob for the CONS (carrier operated noise switch - a squelch control) and only one audio output vs push-pull. A NC-100 schematic will get you mighty close.


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PostPosted: Jun Wed 10, 2009 1:23 am 
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Yeah...

I remember that CONS...it was part of the RCK unit.

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PostPosted: Jun Thu 11, 2009 12:11 am 
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Thanks for the info and comments everyone. The RCF does indeed look like an NC-100 in many respects. Carl, that link you provided did clear up some of the mysteries. I now know that the INS switch on the front panel operates a squelch circuit and INS stands for Interstation Noise Suppression. The two pots on the bracket at the rear of the chassis and the extra 6C5 are associated with the INS.

The output is single-ended, not P-P like the NC-100, so an interstage transformer is not needed for phase inversion. The NC-100 uses an electrodynamic speaker, but the RCF uses a PM speaker and the radio has a second filter choke (to replace the field coil) and an output transformer both mounted on the chassis.

I still don't have a diagram and there are remaining questions about the details of the INS circuit. I suppose I could just bypass it for now and try to figure it out when everything else is working.

Everything from the antenna terminals to the detector looks just like the NC-100 and I have the manual for that, so I have a good start. Thanks again for your input. --Ed

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