Hello All,
I was told by a ham during a QSO that if I buy a matched pair of 6146b's, I
would not need to neutralize them?? Is that true?

Thanks KB3IBT

"KB3IBT Dan K" wrote in message
news:6vNvi.1387$hK5.1064@trndny02...
Hello All,
I was told by a ham during a QSO that if I buy a matched pair of 6146b's,
I would not need to neutralize them?? Is that true?

Thanks KB3IBT


No.

On Mon, 13 Aug 2007 00:22:26 GMT, KB3IBT Dan K wrote:

I was told by a ham during a QSO that if I buy a matched pair of
6146b's, I would not need to neutralize them?? Is that true?

No.

"KB3IBT Dan K" wrote in message
news:6vNvi.1387$hK5.1064@trndny02...
Hello All,
I was told by a ham during a QSO that if I buy a matched pair of 6146b's,
I would not need to neutralize them?? Is that true?

Thanks KB3IBT


So why should I get a matched pair?
I could save some money if I don't.

"KB3IBT Dan K" wrote in message
news:nc6wi.1578$jU4.1482@trnddc02...

"KB3IBT Dan K" wrote in message
news:6vNvi.1387$hK5.1064@trndny02...
Hello All,
I was told by a ham during a QSO that if I buy a matched pair of 6146b's,
I would not need to neutralize them?? Is that true?

Thanks KB3IBT


So why should I get a matched pair?
I could save some money if I don't.


Matched pair implies the tubes will be drawing equal current for a given
grid bias; there is no way to "balance" the tubes in most rigs.

Neutralization is used to cancel unwanted capacitive coupling between
the internal tube elements, which varies by manufacturer and tolerances.

Usually you don't need a "matched pair"; I'd go with new tubes of the
same manufacturer and relatively close production dates. In other
words, don't mix a used RCA 6146A with a new imported 6146B
and expect the tubes to last.

Oh, wow, thanks for the explanation Uncle Peter. I really appreciate it! I'm
gonna stick with new tubes. I hope my TS-530 will be able to tune up. Its
been sitting almost a year collectin dust next to my beloved TS-870.
I tried tuning the 530 this past Sunday and it wouldn't budge. Nothing at
all. It still receives pretty good.

Again, Thanks!



"Uncle Peter" wrote in message
...

"KB3IBT Dan K" wrote in message
news:nc6wi.1578$jU4.1482@trnddc02...

"KB3IBT Dan K" wrote in message
news:6vNvi.1387$hK5.1064@trndny02...
Hello All,
I was told by a ham during a QSO that if I buy a matched pair of
6146b's, I would not need to neutralize them?? Is that true?

Thanks KB3IBT


So why should I get a matched pair?
I could save some money if I don't.


Matched pair implies the tubes will be drawing equal current for a given
grid bias; there is no way to "balance" the tubes in most rigs.

Neutralization is used to cancel unwanted capacitive coupling between
the internal tube elements, which varies by manufacturer and tolerances.

Usually you don't need a "matched pair"; I'd go with new tubes of the
same manufacturer and relatively close production dates. In other
words, don't mix a used RCA 6146A with a new imported 6146B
and expect the tubes to last.

On Aug 13, 8:55 pm, "KB3IBT Dan K" wrote:
Oh, wow, thanks for the explanation Uncle Peter. I really appreciate it! I'm
gonna stick with new tubes. I hope my TS-530 will be able to tune up. Its
been sitting almost a year collectin dust next to my beloved TS-870.
I tried tuning the 530 this past Sunday and it wouldn't budge. Nothing at
all. It still receives pretty good.

It's not so obvious that a transmitter that doesn't "budge" obviously
needs new finals. If the last time the transmitter was used there was
a big puff of smoke from the final compartment and a lot of blue
flashing, maybe, but I've smoked far more plate chokes and HV coupling
or bypass caps than finals over the years.

Does it show any plate current at all? The finals are biased for AB1
or so and probably should draw 50 mA or so (see your manual for
details) when keyed up and no signal. If so, as you tweak the bias
(not sure where it is in a TS-530 but there must be a final bias pot)
does the current behave semi-linearly?

If you have bias which behaves right but no signal out, I'd suspect
something in the drivers, not the finals.

If you're sucking major current when there's no signal, then the tubes
might be gassy or maybe the screen current is out of whack or you've
got some super-nasty parasitics (which actually comes back to the
neutralization you asked about).

If the bias isn't behaving right, I'd suspect plate choke/bias
circuitry/screen supply/plate supply.

If it sucks current but fails to load up, then a bad coupling
capacitor or bad bandswitch or pi-network variables.

Tim.

On Aug 13, 8:55 pm, "KB3IBT Dan K" wrote:
Oh, wow, thanks for the explanation Uncle Peter. I really appreciate it! I'm
gonna stick with new tubes. I hope my TS-530 will be able to tune up. Its
been sitting almost a year collectin dust next to my beloved TS-870.
I tried tuning the 530 this past Sunday and it wouldn't budge. Nothing at
all. It still receives pretty good.

I gave you a lot of places to look in my other post, but suddenly the
"Nothing at all" rings a very clear bell. Replace the driver, a
12BY7A, first before suspecting the finals, and especially if the bias
current in the finals is doing the right thing.

Tim.

Tim Shoppa wrote:
On Aug 13, 8:55 pm, "KB3IBT Dan K" wrote:
Oh, wow, thanks for the explanation Uncle Peter. I really appreciate it! I'm
gonna stick with new tubes. I hope my TS-530 will be able to tune up. Its
been sitting almost a year collectin dust next to my beloved TS-870.
I tried tuning the 530 this past Sunday and it wouldn't budge. Nothing at
all. It still receives pretty good.

I gave you a lot of places to look in my other post, but suddenly the
"Nothing at all" rings a very clear bell. Replace the driver, a
12BY7A, first before suspecting the finals, and especially if the bias
current in the finals is doing the right thing.

Tim.

May be worth checking the SG switch, I've had a few in for repair that
had it switched off.

Steve H

Hi,

can you check the HV reading from teh front meter,
s/b 850-900v if half that electrolytic cap(s) need replacement.
digikey has modern caps that fit nice, info in the yahoo forum below.

you may not have a tube problem, could be something else,
as posted, more info is needed to help figure it out.

also, is screen grid switch turned on (black switch at rear of radio).
it is easy to slide it off if radio is moved and no output if it is off.

avoid the imported tubes, others have had instant tube failures using
made in china tubes and this also takes out cathode resistors.
rf parts and www.surplusales.com have us made tubes,
surplussales has tube specials along with the driver tube.

join other ts-5xx/8xx fans here,

http://groups.yahoo.com/group/TS-520_820_530_830/

lot of info in file section, messages are public access.
tube neutralization info in the public and file sections.

these radios don't like to sit unused, most of the time they need
a cleaning of the band switches and you are on the air again.

could be driver tube, always change it first (save the old driver
for use in another radio) before the finals.

73 james