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 Post subject: Channel Master 6523 "Trans World" portable - I.F.
PostPosted: Aug Fri 16, 2013 2:34 am 
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Joined: Feb Thu 24, 2011 3:13 pm
Posts: 913
Location: Ironwood, MI
I just finished an extensive restoration of a childhood Channel Master 6523 "Trans World" 3-band portable. The Howard W. Sams Photofact has been my primary guidance but here's the
sticky point: The Sams document specifies in its alignment procedure to inject 470 KC to align the I.F. The pictoral diagrams all identify the transformers as "470 KC." HOWEVER the schematic identifies the I.F. transformers as "455 KC" and the back cover of the radio has "I.F. 455 KC" silk-screened on it. If I align to 470 or I align to 455 it does not seem to make a lot of difference although I am wondering if I am losing some performance in roll off due to tracking errors if I align on a frequency for which the Channel Master is not strictly designed.

Has anyone experienced similar anomalies with Channel Master/Howard Sams and their interchanging the I.F. frequencies? If so, which one worked best for you?

Thanks.


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 Post subject: Re: Update on Channel Master 6523
PostPosted: Aug Fri 16, 2013 12:55 pm 
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Joined: Feb Thu 24, 2011 3:13 pm
Posts: 913
Location: Ironwood, MI
After doing another alignment n the 6523 it does seem to perform better when aligned
at 470 KC. I may have peaked on the wrong resonant point earlier which led me to erroneously believe (and state on this forum) that there was "little difference" between aligning to 455 and 470 KC.

My feelings today...right now...at this exact minute and second...(subject to change)...are that the Howard Sams document is sloppily incorrect (schematic wrong, alignment procedure correct) and the silk-screening on the rear of the radio is incorrect and the IF is indeed 470 KC..

As always, input is always welcomed and appreciated.


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 Post subject: Re: Channel Master 6523 "Trans World" portable - I.F.
PostPosted: Aug Fri 16, 2013 7:53 pm 
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Joined: Jun Tue 21, 2011 8:27 pm
Posts: 3288
Location: Flint Hill, Virginia
Remember this was all produced in the sixties and seventies when even simple things
we take for granted were done by hand. Addition and subtraction comes to mind.
The company changed hands at least once and given the myriad of data they printed,
its pretty darn awesome there weren't more errors. Still, I complain when I find one. :)

Keep us up to date on how the restoration goes,
~ Mitch ~


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 Post subject: Re: Channel Master 6523 "Trans World" portable - I.F.
PostPosted: Aug Sat 17, 2013 11:15 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 4866
Location: Gainesville, Florida
did you adjust everything else after changing IF frequensy ?


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 Post subject: Re: Channel Master 6523 "Trans World" portable - I.F.
PostPosted: Aug Sun 18, 2013 2:07 am 
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Joined: Feb Thu 24, 2011 3:13 pm
Posts: 913
Location: Ironwood, MI
I sure did. I did an end-to-end RF alignment and reset the AVC voltage. I'd done the same at 455 and when sliding it up to 470 it seemed to give me better performance on all 3 bands.


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