[Boatanchors] Halli SX-111

[Carl]

I probably do more radios of that era than you and have never observed that 
problem. Same when at National and moonlighting at retail shops.

There are a few home radios where the outer foil of the cap and its 
placement across the socket act as a shield. A disc cap will cause 
oscillation but a low value carbon resistor right at the grid and, if 
necessary the screen leads cures that right up. Thats only with 2.5V and 6V 
equivalent glass tubes. Earlier ones dont have enough gain to take off.

Many radios specifically detail about lead dress to stabilize. I have all 
the Riders as well as many, many manufacturers service material and repair 
shop bulletins.

Ive been using discs for ages and have yet to have any more than a short 
passing problem.

Carl
KM1H



----- Original Message ----- 
From: "Glen Zook" <gzook at yahoo.com>
To: <boatanchors at mailman.qth.net>; "rbethman" <rbethman at comcast.net>
Sent: Sunday, August 23, 2009 3:34 PM
Subject: Re: [Boatanchors] Halli SX-111


I have found, especially when repairing radios made in the 1930s, that 
certain circuits actually need the bypass capacitor to be leaky.  In those 
circumstances I add a resistor (usually between 470K and 1meg) in parallel. 
This seems to be true especially in oscillator stages.

Glen, K9STH

Website:  http://k9sth.com


--- On Sun, 8/23/09, rbethman <rbethman at comcast.net> wrote:

My experience is indeed the 50kc IF and in the 50.5 kc IF in specifically in 
the SX-101s.

I began replacing them one at a time. Then test for function. I changed one 
that was a stage bypass cap and the receiver stopped working. I went back, 
put the pink Tiny Chief back where it just came out of and got the receive 
back.

I'm not sure if it is inductance or resistance. I do not have a highly 
outfitted bench as some do. Some things I have to either calculate or best 
guess it. This IS frustrating to say the least.

Roy Morgan has also commented on this VERY same thing. Where in nine years 
of archived E-Mail? I have no clue!

It isn't an absolute thing, just something to be aware of.



______________________________________________________________
Boatanchors mailing list
Home: http://mailman.qth.net/mailman/listinfo/boatanchors
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Boatanchors at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html