Darrell wrote:
I had one of the first Heathkit HW-100's. I was on a waiting list before
they ever made the first shipment. Mine came with 6146B's. If there was any
change, it would have to of been made in the first few hundred. Like I have
said, the card that came with my HW-100 said they were equivalent. I've
seen dozens of them with both versions. They all worked just fine. I still
say it's nothing but an internet myth.

Darrell

Doing some casual research, I find that Heath did indeed know about the problem,
as early as January, 1978, but in 1979, when they had no choice, they gave approval
to use the 6146B.

-----------------------QUOTED FROM HEATHKIT's CHANGE BULLETINS---------------------

************************************************** *****************************
JANUARY 20, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-18

RF CHOKE IN FINAL PLATE CIRCUIT OVERHEATS OR
DIFFICULT TO NEUTRALIZE ON 10 METER & 15 METER BANDS

6146B tubes in the final amplifier may be causing this problem. To
correct, replace with 6146A tubes.

A label will be installed on the back panel of the HW-101 recommending
the use of 6146A tubes only. The 6146B tubes should not be used as a
replacement.
-----------------------------------------------------------------------------

------------------------------------------------------------------------------
NOVEMBER 20, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-39

IDENTIFICTION OF THE 6146A TUBES

The 6146A tubes [PN 411-75] used at V8 and V9 of this unit are marked
'6146A' in white ink on the side of the tube. These tubes may also have
'6146B' etched in the galss. These tubes have been reworked by G.E. and
are acceptable for use in the HW-101. Most tube cartons will contain the
following insert to explain the situation to the customer:

IMPORTANT INFORMATION;
THE TUBE SUPPLIED WITH THIS NOTICE IS TYPE 6146A, AS PRINTED ON ONE SIDE
OF THE TUBE, EVEN THOUGH THERE MAY BE A 6146B ETCHED ELSEWHERE ON THE
TUBE ENVELOPE.

ALWAYS REPLACE V8 AND V9 WITH 6146A TYPE TUBES

Replace the backing from this label and place the label at any convenient
location inside the cabinet top.
------------------------------------------------------------------------------


------------------------------------------------------------------------------
May 15, 1979
HW-101 Bulletin No:
SSB Transceiver HW-101-49

Changeover To 6146B Finals

The 6146A final amplifier tubes are no longer available from the
manufacturer. Future productions runs will use the 6146Bs. These are GE
brand tubes and have been tested in the HW-101. No difficulty was
encountered in neutralizing the finals; nor did the RF choke in the final
plate circuit overheat. The tube replacement label [PN 390-146] should
be removed from all units brought in for service.
-------------------------------------------------------------------------------

-----------------------QUOTED FROM HEATHKIT's CHANGE BULLETINS---------------------

I haven't yet found the bulletin mentioned by Zook, but everything he stated fits the
above bulletins.

To recap, he said that 1) heath forbid the use of 6146B's
2) Heath switched to B's when GE stopped making A's
3) Heath came to regret it.

I need to find the Bulletins from past 1979. That is where the meat is.

-Chuck Harris