[Boatanchors] 6146 question

[Paul Christensen]

P.S.

Also notice that the GE 6146B has been "re-worked," using Heath's wording
I've no idea what was reworked, likely a change in interelectrode
capacitance.

Paul, W9AC

-----Original Message-----
From: boatanchors-bounces at mailman.qth.net
<boatanchors-bounces at mailman.qth.net> On Behalf Of Paul Christensen
Sent: Monday, January 29, 2024 9:19 AM
To: boatanchors at mailman.qth.net
Subject: Re: [Boatanchors] 6146 question

I found the Heath HW-101 service bulletins.  The first two bulletins
emphasize the 6146A.  However, notice the change in the third service
bulletin where Heath states that GE-branded 6146B tubes may be used in the
HW-101: 

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

IDENTIFICATION 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 glass. 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 SSB TRANSCEIVER
BULLETIN NO:  	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.

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