A question on tube rigs in general, Kenwood in particular

[billcalley]

Hi All,

I have a Kenwood TS-530S, but I'm sure this question applies to
most other tube rigs: Why is there even a TUNE setting on the MODE
switch? I know that with this switch engaged the "input power to the
final section is reduced to prevent tube damage during tune-up", but
why not just adjust CAR (CAR LEVEL CONTROL) downward for this step,
since CAR also controls "carrier level during CW operation". Is it
simply a matter of convenience, or do these controls actually do
somewhat different things?

And while I'm on that subject of carrier level, I need to lower
my
100 watts to about 10 watts. Is the best way to do this by simply
lowering the CAR control? Does this technique give all the
advantages, such as more protection to the finals (with a high VSWR)
and generally longer tube life?

Another quick question for anyone who is familiar with the
Kenwood
TS-530S with the 500Hz CW filter installed, but I noticed that unless
I move IF-SHIFT counter-clockwise, the audio output is not centered
on
800 Hz, but more like 1200 Hz or so. Is this normal for Kenwoods?


Thanks for any help!


-Bill

 

[Joerg]

Hi All,

I have a Kenwood TS-530S, but I'm sure this question applies to
most other tube rigs: Why is there even a TUNE setting on the MODE
switch? I know that with this switch engaged the "input power to the
final section is reduced to prevent tube damage during tune-up", but
why not just adjust CAR (CAR LEVEL CONTROL) downward for this step,
since CAR also controls "carrier level during CW operation". Is it
simply a matter of convenience, or do these controls actually do
somewhat different things?

Not so much for convenience I guess but more for safety (for the tubes).
I have seen people happily cranking the geared inductor on the tuner box
while being blissfully unaware that the plates of their 6164's were
already going from orange to white.

And while I'm on that subject of carrier level, I need to lower
my
100 watts to about 10 watts. Is the best way to do this by simply
lowering the CAR control? Does this technique give all the
advantages, such as more protection to the finals (with a high VSWR)
and generally longer tube life?

Usually, yes. But if you are talking about a separate power amplifier
that could suffer damage when hit with a lot more than 10W I'd make sure
there is some hard limit. Just so you can't accidentally catch that CAR
control with a shirt sleeve and .... kablouie.

Another quick question for anyone who is familiar with the
Kenwood
TS-530S with the 500Hz CW filter installed, but I noticed that unless
I move IF-SHIFT counter-clockwise, the audio output is not centered
on
800 Hz, but more like 1200 Hz or so. Is this normal for Kenwoods?

Sounds a bit highish but then again the last Kenwood I had was their old
receiver 9R59-DS. Probably the first large production run they did in
that field, more than 30 years ago.

 

[billcalley]

Not so much for convenience I guess but more for safety (for the tubes).
I have seen people happily cranking the geared inductor on the tuner box
while being blissfully unaware that the plates of their 6164's were
already going from orange to white.


Usually, yes. But if you are talking about a separate power amplifier
that could suffer damage when hit with a lot more than 10W I'd make sure
there is some hard limit. Just so you can't accidentally catch that CAR
control with a shirt sleeve and .... kablouie.


Sounds a bit highish but then again the last Kenwood I had was their old
receiver 9R59-DS. Probably the first large production run they did in
that field, more than 30 years ago.

Great stuff -- thanks again for more great info, Joerg!

Best Regards,

-Bill