[Hallicrafters] S20-R band 4 LO warble

[Richard Knoppow]

----- Original Message ----- 
From: "James Liles" <james.liles at comcast.net>
To: <hallicrafters at mailman.qth.net>
Sent: Tuesday, July 26, 2011 6:02 PM
Subject: [Hallicrafters] S20-R band 4 LO warble


> Hi Richard and Paul:
>
> The 6K8 LO in the S20-R, SX24, and SX-25 create a ratty 
> note or for lack of
> a better word Warble on band 4.  A spectrum analyzer shot 
> of the oscillator
> on band 4 looks like a jagged waterfall kinda like a bunch 
> of gerbils
> running in a treadmill with the a bunch of marbles on a 
> tin barn roof!!!  It
> is not a result of physical movement or jarring.  The 
> output is pristine on
> the other bands.  Don`t want to make major mods --- It`s 
> my original
> receiver --- maybe just a change of the 6K8 to something 
> else.
>
> Kindest regards Jim K9AXN

    I've encountered a rough note from heater to cathode 
leakage (maybe) in 6K8 tubes. Had the problem in my HQ-129-X 
on the highest band. I tried about four tubes before I found 
one that was clean. I don't know what can be used in place 
of a 6K8 without some surgery. I would not have described 
the sound as warbling but it certainly was not as stable as 
it should have been. Tapping on the tube doesn't change it 
or fix it.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com