[AMRadio] APA-38 panoramic Help


Al ae6cm ae6cm at sonic.net
Sat Jul 17 09:34:47 EDT 2010


The "VHF" column in CQ for July 1959 has a brief write-up for a conversion, 
then some more info in the January 1960 column.  Basically, add a couple 6.5 
MHz crystals in the IF amp to narrow it up, then build a converter to 
convert to the existing 30MHz front end.

Al

----- Original Message ----- 
From: <doxemf at aol.com>
To: <amradio at mailman.qth.net>
Sent: Sunday, July 11, 2010 11:36 AM
Subject: [AMRadio] APA-38 panoramic Help


>
> Does anyone have experience with or a manual/conversion docs for this 
> panoramic unit?
>
> This is a long narrow body unit that was used with the APR-4 search 
> receiver and in the PBM-5S Mariner Aircraft from what little info I have 
> been able to find.
>
> The crt has about a 2-1/3 diameter round screen. Power supply was internal 
> 400cy >
>
> The original IF input frq was 30 mhz with the units own IF at 6.5.
>
> The two units that I have were modified to use an external 60cy 
> transformer that I have, and there is a crystal controlled converter strip 
> added using 2 miniature tubes, a 243 case 6.XXX xtal and 3/4" 
> transformers. This strip looks like a factory build and mounts where the 
> original converter circuit was.
> The schematic is included in an old CQ conversion handbook but nothing is 
> documented for the converter altho conversion for 455 is mentioned.
>
> I suspect that the units that I have could have been late production with 
> the converter or possibly a published mod.
> Since the original circuitry was MFP treated it is difficult to 
> troubleshoot without a good parts layout. The converter has not been 
> treated and easily accessable.
> One unit does power up but there are leaky capacitor issues evident from 
> an erratic display trace.
>
> If anyone might have further info or can point me to a manual or magazine 
> issue with the full conversion it would be appreciated. This is a nice 
> small Panoramic display similiar to the Halli Skyrider accessory.
>
> Thanks,
> Wm,
> KB3DKS in 1 Land

The "VHF" column in CQ for July 1959 has a brief write-up for a conversion, 
then some more info in the January 1960 column.  Basically, add a couple 
6MHz crystals in the IF amp to narrow it up, then build a converter to 
convert to the 30MHz front end.

Al 



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