[ARC5] BC-611 F Data Needed

[Robert Downs]

I would say with BC-611-F's that resistor drift would be the second thing to
check as resistor value drift wouldn't usually make the radio totally not
work but an open ID winding certainly will.  One other age related problem
that I've seen a couple of times is that a heavy MFP varnish layer plus
unknown storage conditions can cause you to be unable to tune the antenna
with the proper antenna coil installed.  The condition is apparently rare
but I have encountered two radios where to get the antenna to resonate, I
had to change the coil that covers 3885 KC to the next one up.  After which
the radio worked fine.

 

Robert Downs

 

From: arc5-bounces at mailman.qth.net [mailto:arc5-bounces at mailman.qth.net] On
Behalf Of Robert Eleazer
Sent: Tuesday, April 21, 2020 11:55
To: arc5 at mailman.qth.net
Subject: [ARC5] BC-611 F Data Needed

 

The first thing you need to do is check all the resistors in those BC-611's.
It is not guaranteed that all the carbon composition resistors in those rigs
have had value excursions outside of their design limits but it is very
likely.  I have seen that occur not only on WWII vintage equipment but even
with much newer carbon resistors that have been just sitting in a box on the
shelf.

 

The GRC-9 I have been working on it dates from 1950 and all but three or
four resistors had to be replaced or at least paralleled with additional
resistors to get the circuit values back into spec.

 

As to why all of them were not found to be bad, I can only assume that some
manufacturers did a better job on stability than others.

 

Good Luck!

 

Wayne

WB5WSV     

 


 
<http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_cam
paign=sig-email&utm_content=emailclient> 

Virus-free.
<http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_cam
paign=sig-email&utm_content=emailclient> www.avg.com 

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/arc5/attachments/20200421/b091446f/attachment.html>