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.

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