[Milsurplus] HELP ON FILTER

[WA5CAB@cs.com]

Norm,

GN-50-B is the 500/6.3VDC generator used on the PE-162-C.  F-147/U is the 
filter box off of the PE-162-C (and those PE-162-B on which the MWO was 
accomplished).  Its intputs to the terminal strip are 500 & 6.3VDC from the 
GN-50-B.  Outputs are 500/6.3VDC to any one of the three radios plus 6.3VDC 
from the 4-pin connector for the battery in the PP-39/TRC-2.

Before starting any filter installation or modification project, it would be 
best to first identify the hash source.  Disconnect the antenna lead and 
ground the antenna post.  If the hash disappears or decreases noticably, then 
the hash or some of it is being radiated from elsewhere in the vehicle and no 
amount of filtering on the radio power inputs is going to help.  You'll need 
to track down the source and eliminate it there.  One common problem in 
restored vehicles is that the restorer didn't replace all of the grounding 
straps.  Also, run the radio receiver with the engine shut off as a cross 
check that the hash is or isn't coming from the vehicle.

If the hash level doesn't change, then it is probably coming from the power 
source.  I forget which one you are using.  If the PE-237, replace it with a 
DY-88 or -105 (somebody with an MB, WC or Weasel will appreciate the PE-237 
being available).  If you are using one of the dynamotor/vibrator units, then 
there may be something wrong in it.  Generally, if one of the military sets 
(at least the later WW-II ones on) is installed according to the pertinant 
pubs, with all of the components called for, they will work satisfactorily 
unless some of the components are defective.

>I have a filter unit, F-147/U which has a number of capacitors, "cored" =
choke, "RF" type chokes and other parts which is designed for a hash =
filter.

The box indicates it is for use on:
    AN/GRC-9
    SCR-694C
    AN/TRC-2
    PE-162-C
    GN-50-B

73
Robert Downs
Houston
<wa5cab@cs.com>


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