Just recently got a HW-101, with low power out,I can get a few more
watts by adjusting the bias slightly above the 20ma mark, how safe is
it this?
Since I dont have spare 6146's what should I be looking for that could
be a problem other than the finals?

Thanks in advance...Gil

gil wrote:
Just recently got a HW-101, with low power out,I can get a few more
watts by adjusting the bias slightly above the 20ma mark, how safe is
it this?
Since I dont have spare 6146's what should I be looking for that could
be a problem other than the finals?

Thanks in advance...Gil


Sorry, but the finals are the usual reason for low output. You will go
through many sets of finals before you wear out the driver.

Make sure that your replacement finals are 6146, or 6146A's, never B's!

Note, 6146W's can be all three types. The later 6146W's are B's.

Don't get creative with the bias. It has nothing to do with the power
output, but everything to do with balancing tube life with low distortion.

When your bias is low, your tubes are cut-off on opposite cycles, and you get
cross over distortion. When your bias is high, the tubes are approaching
class A operation where they make a good expensive short lived shack heater.

-Chuck

Make sure that your replacement finals are 6146, or 6146A's, never
B's!


I've got to challenge this statement. This rumor has been circulating for
several years now. When I received my new HW-100 from Heathkit in 1968, it
came with RCA 6146B's. There was a note enclosed that said that they(Heath)
were having problems getting 6146A's and that the 6146B's would work fine.
They did. The radio neutralized without any problems and stayed that way.

I had the radio for about 10 years and when I sold it, it had the same
tubes and still produced full output.

Darrell

Darrell wrote:
Make sure that your replacement finals are 6146, or 6146A's, never

B's!



I've got to challenge this statement. This rumor has been circulating for
several years now. When I received my new HW-100 from Heathkit in 1968, it
came with RCA 6146B's. There was a note enclosed that said that they(Heath)
were having problems getting 6146A's and that the 6146B's would work fine.
They did. The radio neutralized without any problems and stayed that way.

That there are big differences between the 6146(A), and the 6146B is not
a rumour. It shows up on the spec sheets as different interelectrode
capacitances. The 6146B had a bigger plate size, and handled something like
a third more plate dissipation.

It would have been better if I had said that you must use which ever was
certified by the manufacturer, straights, A's or B's.

Heath had already made the necessary modifications to the final section of your
radio. You would probably have had problems if you tried A's.

The 6146B should have been issued a new number.

-Chuck

Yes, there are diffences between the A and B versions. There are also
differences between various manufacturers. However, that doesn't change
the fact that the two tubes are generally interchangeable. All of the
hoopla got started when an article was written about some problems
Motorola had with some VHF gear that was designed around the 6146A and
had fixed neutralization. Their attempt to stadardize around the 6146B
caused them some problems.

The bottom line is, if it will neutralize, it will work fine. Frankly,
I've never found a piece of ham gear they won't work in. A partial list
of radios I have used them in with NO PROBLEMS:

COLLINS: KWM2A, 32S3A
GONSET: Commander
HEATHKIT: DX-60, DX100, HW-100, HW-101, Apache
JOHNSON: Ranger, Valiant, Viking II
KNIGHT: T-150
MULTI ELMAC: AF67, AF68
WRL: Globe Scout 680A

There are others. Like I said, I've never found an example where they
won't work, and work well. I haven't tried them on VHF equipment. I'll be
the first to admit that there could be a problem there.

Darrell






Darrell wrote:
Make sure that your replacement finals are 6146, or 6146A's, never

B's!



I've got to challenge this statement. This rumor has been circulating
for several years now. When I received my new HW-100 from Heathkit in
1968, it came with RCA 6146B's. There was a note enclosed that said
that they(Heath) were having problems getting 6146A's and that the
6146B's would work fine. They did. The radio neutralized without any
problems and stayed that way.

That there are big differences between the 6146(A), and the 6146B is
not a rumour. It shows up on the spec sheets as different
interelectrode capacitances. The 6146B had a bigger plate size, and
handled something like a third more plate dissipation.

It would have been better if I had said that you must use which ever
was certified by the manufacturer, straights, A's or B's.

Heath had already made the necessary modifications to the final
section of your radio. You would probably have had problems if you
tried A's.

The 6146B should have been issued a new number.

-Chuck

Darrell wrote:
Yes, there are diffences between the A and B versions. There are also
differences between various manufacturers. However, that doesn't change
the fact that the two tubes are generally interchangeable. All of the
hoopla got started when an article was written about some problems
Motorola had with some VHF gear that was designed around the 6146A and
had fixed neutralization. Their attempt to stadardize around the 6146B
caused them some problems.

The bottom line is, if it will neutralize, it will work fine. Frankly,
I've never found a piece of ham gear they won't work in. A partial list
of radios I have used them in with NO PROBLEMS:

COLLINS: KWM2A, 32S3A
GONSET: Commander
HEATHKIT: DX-60, DX100, HW-100, HW-101, Apache
JOHNSON: Ranger, Valiant, Viking II
KNIGHT: T-150
MULTI ELMAC: AF67, AF68
WRL: Globe Scout 680A

There are others. Like I said, I've never found an example where they
won't work, and work well. I haven't tried them on VHF equipment. I'll be
the first to admit that there could be a problem there.

Darrell


I have used the A's and B's interchangeably in both Heath SB-102 and
Collins S-line with no problems. Chuckie doesn't know everything even
though he thinks he does.

Darrell wrote:
There are others. Like I said, I've never found an example where they
won't work, and work well. I haven't tried them on VHF equipment. I'll be
the first to admit that there could be a problem there.

Exciter for the RCA FM-1 broadcast transmitter needs a capacitor change
if you go to the B version. Details are in the manual. This is a
single-ended gain stage that drives about 10W into the final.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

The required screen voltage for the Bs is higher also.

73, K8AC

"Chuck Harris" wrote in message
...
Darrell wrote:
Make sure that your replacement finals are 6146, or 6146A's, never

B's!



I've got to challenge this statement. This rumor has been circulating for
several years now. When I received my new HW-100 from Heathkit in 1968,
it came with RCA 6146B's. There was a note enclosed that said that
they(Heath) were having problems getting 6146A's and that the 6146B's
would work fine. They did. The radio neutralized without any problems and
stayed that way.

That there are big differences between the 6146(A), and the 6146B is not
a rumour. It shows up on the spec sheets as different interelectrode
capacitances. The 6146B had a bigger plate size, and handled something
like
a third more plate dissipation.

It would have been better if I had said that you must use which ever was
certified by the manufacturer, straights, A's or B's.

Heath had already made the necessary modifications to the final section of
your
radio. You would probably have had problems if you tried A's.

The 6146B should have been issued a new number.

-Chuck

The only difference in capacitance I see is Cgp, 0.24 pF for the 6146A
vs. 0.22 pF for the 6146 and the 6146B. Doesn't sound like any
difference at all, unless maybe the average values are quite a bit
different for the 6146B vs. the other two (but what would cause that?).
I don't question those who say there's a problem with some rigs, but
on paper all three tubes do seem to be the same (at the lower screen
voltage the 6146 is designed for). Apparently RCA thought the same
thing.

No conclusions, just ruminations...

73,
Mike, KK6GM

"Mike Silva" wrote in news:1117989475.147628.191590
@f14g2000cwb.googlegroups.com:

The only difference in capacitance I see is Cgp, 0.24 pF for the 6146A
vs. 0.22 pF for the 6146 and the 6146B. Doesn't sound like any
difference at all, unless maybe the average values are quite a bit
different for the 6146B vs. the other two (but what would cause that?).
I don't question those who say there's a problem with some rigs, but
on paper all three tubes do seem to be the same (at the lower screen
voltage the 6146 is designed for). Apparently RCA thought the same
thing.

No conclusions, just ruminations...

73,
Mike, KK6GM





There is no real difference. The 6146B was very popular in the 1960's.
Everyone was switching over to them with no problems. Trust me, I was
there. One guy writes an article expressing an erroneous opinion about them
and it becomes fact. It's nothing but an internet myth. Maybe he wanted to
corner the market on the 6146B's? Like I said, I'm still looking for a
radio they won't work in.


Darrell