[Milsurplus] Using GDO to check bc-348 coils.

[jcoward5452 at aol.com]

And your problem is.....??????
 The radio works, enjoy it!
  This is a general coverage rx designed for average at best operators with a statistically short life span, sad to say. 

 As for the sqeaky band, I had a similar situation with one that had a problem with "back lash" in the main tuning cap.Make sure the tuning cap is mechanically sound.And this would appear more or less on all bands. Also, I've had problems with those pesky trimmer ACP caps in the rf "boxes". Sometimes the retaining sleeve (looks like a nut but isn't)will fracture and now you have a variable Variable cap.This one took a day to figure out with a magnifying glass and a microscope! Actually you can lightly "poke" these with a tuning tool to see if they have a mechanical integrity problem.

Good luck, these are fine receivers. I am useing my first that I got as a chassis from tech school back in the late '70's for 20 bucks. It's a "C" modified to "S" .We (college buddies) used to listen to AFRTS baseball games and watch the video on local TV.AFRTS was a second or two ahead of the local TV.Imagine the hilarity after a couple beers! It is fairly well restored now thanks to members of this and other related lists.
 Jay KE6PPF




-----Original Message-----
From: John Hutchins <olegerityincj at austin.rr.com>
To: Milsurplus <Milsurplus at mailman.qth.net>
Sent: Mon, Sep 27, 2010 7:25 pm
Subject: [Milsurplus] Using GDO to check bc-348 coils.


  All -
Thanks for all the advice to get you all up to date where I am at in 
estoring my frist
C-348R.   Have replaced all the paper bypass caps, all but 6 .01 mica 
y pass caps.
es even the sneaky .01uf in the BFO can.  Checked all the RF/OSC micas 
hat feed the Tuning cap.
ost were on the mark ~< 3% off of posted value.  All caps checked with 
n LCR meter and RVAM for resistors.
So tuned up the old beast using a HP8601A signal generator.
After the tune up these are the symptoms of receiver; Band 6 18-13.5 Mc  
queaky, wobbly, tuning 13.5 - 14.0 bottom end.  Low ends of 3 bands 
eem to be out of spec.
For each band  wanted to spot what the actual frequency was when setting 
o lowest setting for each band.
and range      low value found at low mark
.  500 - 200                                  200.00 khz
.    3.5 - 1.5                                   1.500 mhz
.    6.0 - 3.5                                   3.447 mhz   - .984%
.    9.5 - 6.0                                   6.040 mhz    .011%
.  13.5 - 9.5                                   9.389 mhz   -.988%
.  18.0 - 13.5                               13.485 mhz   -.9%
ll spotted using  the Frequency counter to monitor the HP8601A signal 
eed to the BC-348R.
I purchased a GDO Millen 90651 tube type, of course! , to see if the 
oils meet published Q at rated frequency. In manual.
So the GDO Millen 90651 is not acting correctly in my opinion.  It goes 
rom .15 ma to 1ma consistently no matter which coil is plugged in when 
olling, tuning,  from low to high frequency.
Since Q = F1 / 2* (F1-F2)
here F2 = 70.7%  of F1
So when the meter is around .15ma it is tough to :
. Get or find a dip;
. Find %70.7 / from the dip
ust a tad difficult?
Since the coils are all good on the GDO.  A signal is detectable on the 
adio.   I was hoping for a pointer to a AH-HA problem, solution.....

Hutch


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