[Hallicrafters] SX-117 Help

[Bill Smith]

Hello to all those who requested an updated schematic of the SX-117.

The schematic and parts list (all I have) have been uploaded to BAMA.  There
are four .gif files, which I then attempted to print out using Internet
Explorer, only to obtain a tiny fraction of the file in print.  I hope you
have a file print utility which will size the file to the correct paper
size.

73 de Bill, AB6MT
billsmith at ispwest.com


> Bill....
> Is there any chance of obtaining a copy of the updated schematic from you.
> I am extremely interested in your finding. I am willing to re-imburse you
> for any related cost.
> Thanks,
> Chuck Kembring WB3LGG
>

>
> The plot thickens..
>
> I rooted through the equipment archives at the Hamilton Wireless
> Association's clubhouse, and lo and behold, found an updated schematic
that
> represents the wiring in this receiver.  To quote:
>
> "Prior to production but after the Handbook was printed, certain wiring
and
> component changes were made in the Model SX-117 Receiver to improve its
> performance.
>
> These changes are contained in the schematic diagram and parts list herein
> enclosed.  Please discard the schematic diagrams and parts list contained
in
> the Handbook and refer to those contained within this sheet whenever
> necessary."
>
> I have only made a cursory review of the two schematics, but changes
> identified so far are:
>
> 1.  Change 1st mixer to a triode configuration.
> 2.  AVC detector bias 1 Meg R63 changed to 6.8 Meg
> 3.  AVC Time constant adjusted in C107 changed from 0.47 to 0.22 Mfd.
> 4.  Grid of AVC amplifier V10A was connected to V9, 6BA6, is now connected
> to the IF transformer following 3rd mixer V8A, 6EA8.  Coupling capacitor
C75
> 0.001 is now C65 100pf.  The old C65 was removed.
> 5.  Selectivity resistors R85 and R87 were changed from 470 ohms to 390
> ohms.
>
> Sensitivity in this receiver seems on a par with the TS-440, but S-meter
> readings are still about 20 db below that of the Kenwood.
>
> 73 de Bill, AB6MT
> billsmith at ispwest.com
>
>