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

Hi,

The bias should be set to 40 mA with both finals installed.
Set the bias by using push to talk mode in SSB, no audio.
If you have another receiver, listen to the carrier output and adjust
the internal notch controls for minimum carrier
with no audio.

Running the HW-101 at 20 mA bias would reduce the output, and worsen the
distortion on SSB.

You can check the balance of your finals by running one at a time,
and setting the bias for 20 mA with a single tube.
(remove the other tube completely, don't just disconnect
the top cap). If the tubes aren't within 5 mA of each other,
I'd look for around for a better balanced set of finals.
I'd do this check on 80m, because by removing one tube,
you are upsetting the neutralization.

73,
Ed Knobloch

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

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

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.

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

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

Cmd Buzz Corey wrote:
Darrell wrote:

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.

Thanks for the vote of confidence!

-Chuck

Cmd Buzz Corey wrote:

Darrell wrote:


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.

Here is a link buzz. If you can find someone to read it to you,
you might find it illuminating:

http://home.comcast.net/~k9sth/The_6...of_Tubes_1.htm


And here's an excerpt from the above link:

"RCA "claimed" that the 6146B was directly interchangeable with the earlier members of the 6146 family. Unfortunately,
this did not hold true in most cases. Collins, Heath, and probably other companies, at first issued various documents
saying that the use of the 6146B in their equipment was "fine". But, this soon proved otherwise!

For example, when the 6146B was used in the Collins 32S-1, 32S-2, 32S-3, 32S-3A, KWM-2, and KWM-2A it was discovered
that the components in the neutralization circuitry "burned up" in a very short amount of time. Thus, Collins had to
retract the statement that it was "OK" to use the 6146B. Then, due to the fact that the United States military
establishment wanted to "standardize" on the 6146W equivalent of the 6146B, the neutralization components had to be
redesigned to allow the 6146B to be used. Fortunately, these changes did not affect the use of the earlier 6146 and
6146A in those transmitters manufactured to use the 6146B. All three types of tubes may be used without any problem in
these transmitters.

Replacing the 6146 / 6146A tubes with 6146B types often results in spurious emissions, parasitic oscillations, etc. This
is due to the fact that there are different bias requirements, different inter-electrode capacitances, etc. of the 6146B
versus the other two. It is often difficult to neutralize 6146B tubes when used in place of the 6146 / 6146A. If
neutralization can be achieved, often it lasts for just a few minutes before the tube(s) goes into oscillation."


Somewhere, in my files, I have the ECO sheets from Collins that discuss the 6146B,
and the changes that need to made for the KWM2(A) to safely use the tube.

Later model KWM-2(A) and 32S transmitters had these changes already incorporated when
they came from the factory.

The changes for the HW100, 101, SB100,and 101, can be found through a little
light searching on the web. The SB102 always had the change, IIRC.

-Chuck