Subject: glowbugs V1 #226
glowbugs           Monday, January 19 1998           Volume 01 : Number 226


Date: Sun, 18 Jan 1998 08:21:41 -0700
From: Steve Lords /WA7ISL <sklords@sprynet.com>
Subject: 6146 blue glow

greetings
  other then a gassy tube, it there any
reason why a 6146 has a blue glow
when under load..

thanks
steve
wa7isl  :)



Date: Sun, 18 Jan 1998 20:34:18 -0500 (EST)
From: lee1@digital.net
Subject: Location of gain pot?

Hi gang
Fiddling around using a scope have been adjusting taps on
70v line trans am using at output trans for 6aq5 tube. 
Was able to increase audio out by over 50% by changing taps.
Now the big question, the 6aq5 outout tube is driven by a 6at6 voltager amp.
where do I put the gain pot? 1 between the det out or in the grid cir of the
6at6
or do I let the 6at6 run wide open and put the pot in the grid cir 
of the 6aq5 output tube as the detector only has an out out of less than .1v
and the gain of the 6at6 is  about 50 it will not over load and clip The
6at6  running wide open still would only have a 5 v sig out with a gain of
100.  I do not know if it really makes a difference.
 If any of you engineer types  can shed some light on thid would appreciate it.



Thank the good LORD for all that you have!!!

67yr old semi disabled senior         trying to get code speed to 13wpm
(stroke got my eyesight, balance & coordination) SO ONLY BA'S  NO SOLID STATE

Leon (lee)  Wiltsey    4600 Lake Haven blvd    Sebring fl. 33872   KF4RCL TECK+



Date: Sun, 18 Jan 1998 20:37:39 -0800 (PST)
From: Ken Gordon <keng@uidaho.edu>
Subject: Re: 6146 blue glow

> greetings
>   other then a gassy tube, it there any
> reason why a 6146 has a blue glow
> when under load..

It kinda depends on WHERE the glow is. A very dark blue glow near the
GLASS usually, in my experience, indicates a good tube with a hard vacuum.
If the glow comes from INSIDE the plate area, it is gassy. Usually, if it
is gassy, it will NOT allow full current to be drawn either.

Ken W7EKB



Date: Mon, 19 Jan 1998 11:10:05 +0100
From: Jan Axing <janax@algonet.se>
Subject: Re: 6146 blue glow

Steve Lords /WA7ISL wrote:
> 
> greetings
>   other then a gassy tube, it there any
> reason why a 6146 has a blue glow
> when under load..

Stray electrons hitting the glass often causes a blue glow depending
on the glass quality and is nothing to worry about. It's an indication
of good vacuum. This can be tested with a magnet, the blue glow will
move when the magnet comes near. Glow caused by gas will not move,
gas ions are way heavier than the electrons.

Power tubes also shows a faint blue glow on the inside of the plate
when drawing current at higher voltages and is also pretty normal.
If this glow is greenish you may suspect gas. Any other color than
dark blue is abnormal.

As usual: be very careful when doing the magnet test, reminding of
the lethal voltages there.

73
Jan, SM5GNN



Date: Mon, 19 Jan 1998 09:15:14 -0500 (EST)
From: lee1@digital.net
Subject: Location of gain pot?

Hi gang
Fiddling around using a scope have been adjusting taps on
70v line trans am using at output trans for 6aq5 tube. 
Was able to increase audio out by over 50% by changing taps.
Now the big question, the 6aq5 outout tube is driven by a 6at6 voltager amp.
where do I put the gain pot? 1 between the det out or in the grid cir of the
6at6
or do I let the 6at6 run wide open and put the pot in the grid cir 
of the 6aq5 output tube as the detector only has an out out of less than .1v
and the gain of the 6at6 is  about 50 it will not over load and clip The
6at6  running wide open still would only have a 5 v sig out with a gain of
100.  I do not know if it really makes a difference.
 If any of you engineer types  can shed some light on thid would appreciate it.



Thank the good LORD for all that you have!!!

67yr old semi disabled senior         trying to get code speed to 13wpm
(stroke got my eyesight, balance & coordination) SO ONLY BA'S  NO SOLID STATE

Leon (lee)  Wiltsey    4600 Lake Haven blvd    Sebring fl. 33872   KF4RCL TECK+



Date: Mon, 19 Jan 1998 16:54:57 +0100
From: Jan Axing <janax@algonet.se>
Subject: Re: Location of gain pot?

lee1@digital.net wrote:

> Now the big question, the 6aq5 outout tube is driven by a 6at6 voltager amp.
> where do I put the gain pot?

I would put it between the detector and the driver tube just to avoid
clipping
in the driver. If the detector output is of high impedance it may be
better to
put it in the output tube grid circuit.

Jan, SM5GNN



End of glowbugs V1 #226
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