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TS-820, xmtr tuning problems



 
 
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  #1  
Old December 24th 03, 02:38 AM
Steve
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Default TS-820, xmtr tuning problems

Hi Gang,
I'm sure not everyone here considers the TS-820 to be a
boatanchor, but it does use tubes. Hoping to get some help.

After being inactive for many years, I finally strung a dipole and
fired up my old Kenwood TS-820S. The transmitter does not
seem to tune up normally. My first thought was the 12BY7A or
the 6146's had died, but they test fine on my tube tester. Also
verified that the HV supply is OK.

Here is a description of whats going on. The 'drive' tunes normally,
as does the idle current for the finals (60 mA). The problem I'm
having is getting ANY plate current while in CW (or tune) mode
(send/rec switch in send position).

Now I know something is fishy because when I transmit SSB into
a dummy load (with output power reduced), I get plenty of power.

Yet another strange thing....I can tune up normally (peak drive, dip plate)
in FSK mode.

Am I doing something wrong, or do I have a problem with my rig?
I do have the manual and have been following their tuning procedure.

Steve W6SSP



  #2  
Old December 24th 03, 03:09 AM
Phil Witt
Guest
 
Posts: n/a
Default

What happens to the grid drive in the tune or cw position. Does it
fall off? Have you tried it with a key instead of the s/r switch?

On Wed, 24 Dec 2003 02:38:34 GMT, "Steve" wrote:

Hi Gang,
I'm sure not everyone here considers the TS-820 to be a
boatanchor, but it does use tubes. Hoping to get some help.

After being inactive for many years, I finally strung a dipole and
fired up my old Kenwood TS-820S. The transmitter does not
seem to tune up normally. My first thought was the 12BY7A or
the 6146's had died, but they test fine on my tube tester. Also
verified that the HV supply is OK.

Here is a description of whats going on. The 'drive' tunes normally,
as does the idle current for the finals (60 mA). The problem I'm
having is getting ANY plate current while in CW (or tune) mode
(send/rec switch in send position).

Now I know something is fishy because when I transmit SSB into
a dummy load (with output power reduced), I get plenty of power.

Yet another strange thing....I can tune up normally (peak drive, dip plate)
in FSK mode.

Am I doing something wrong, or do I have a problem with my rig?
I do have the manual and have been following their tuning procedure.

Steve W6SSP



  #3  
Old December 24th 03, 05:10 PM
Steve
Guest
 
Posts: n/a
Default

Hi Gang,
Thanks for all of the suggestions.

Took a look at the schematic (damn, these are hard to read!), and
discovered that the screen bias on the finals is changed when in TUNE
and CW mode. Somewhere on the 'net, someone mentioned this as
causing a similar problem. Either the screen bias resistors are bad, switch
is dirty, or a connector is flakey somewhere in the circuit. I'll dig into
it and post the results.

For those that mentioned using an external key for tuning, on many rigs
that is how they are tuned, but according to the manual, the TS-820 can
be tuned using the SEND/REC switch in the TUNE and CW modes.
I'm not saying that the book can't be wrong, but I remember this is
how I tuned it many moons ago.

Steve W6SSP


  #4  
Old December 24th 03, 10:47 PM
James B. Geer
Guest
 
Posts: n/a
Default

Just remmber that the 820 tunes up at greatly reduced power output when the
mode switch is in the "tune" position, as opposed to full power when the switch
is in the cw position.

Steve wrote:

Hi Gang,
I'm sure not everyone here considers the TS-820 to be a
boatanchor, but it does use tubes. Hoping to get some help.

After being inactive for many years, I finally strung a dipole and
fired up my old Kenwood TS-820S. The transmitter does not
seem to tune up normally. My first thought was the 12BY7A or
the 6146's had died, but they test fine on my tube tester. Also
verified that the HV supply is OK.

Here is a description of whats going on. The 'drive' tunes normally,
as does the idle current for the finals (60 mA). The problem I'm
having is getting ANY plate current while in CW (or tune) mode
(send/rec switch in send position).

Now I know something is fishy because when I transmit SSB into
a dummy load (with output power reduced), I get plenty of power.

Yet another strange thing....I can tune up normally (peak drive, dip plate)
in FSK mode.

Am I doing something wrong, or do I have a problem with my rig?
I do have the manual and have been following their tuning procedure.

Steve W6SSP


  #5  
Old December 24th 03, 10:57 PM
Bill & Suzie Whatley
Guest
 
Posts: n/a
Default

Also remember that there is a screen voltage switch on the rear panel or the
rig. Be sure it is not set wrong...

73
WA5VRL


  #6  
Old December 25th 03, 02:12 AM
Steve
Guest
 
Posts: n/a
Default

Problem solved!

A couple of folks mentioned that *if* a key was plugged in,
it must be closed *along with* the SEND switch. Yup!

I had my keyer plugged in....

A least I was able to blow out some of the dust that had
collected inside the radio while I was 'troubleshooting'.

Merry Christmas to all.

Steve W6SSP
p.s.-yeah, I feel kinda stupid, but there was NO mention of this in
the book at all


  #7  
Old December 25th 03, 10:15 PM
Dan/W4NTI
Guest
 
Posts: n/a
Default


"Steve" wrote in message
...
Problem solved!

A couple of folks mentioned that *if* a key was plugged in,
it must be closed *along with* the SEND switch. Yup!

I had my keyer plugged in....

A least I was able to blow out some of the dust that had
collected inside the radio while I was 'troubleshooting'.

Merry Christmas to all.

Steve W6SSP
p.s.-yeah, I feel kinda stupid, but there was NO mention of this in
the book at all



When all else fails, don't read the book... hi.

Dan/W4NTI


 




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