6146 Type Tubes

[Jim Simmons, kf4tun]

Read farther down the list, you find this bulletin was rescinded and 6146B
tubes are to be used (no RCA) and the warning label is to be removed.

Jim


----- Original Message -----
From: "Charles Seitz" <cseitz at ENTER.NET>
To: <HEATH at LISTSERV.TEMPE.GOV>
Sent: Wednesday, December 03, 2003 12:44 PM
Subject: 6146 Type Tubes


> I came upon the following service notes for bthe HW-101:
>
> ========================================================
>
> 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 AND 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.
>
>
 ===========================================================================
>
> I'm not sure if these apply to the other HW and SB ham equipments.
Someone
> might compare the final amplifier circuity and mechanical layout of other
> units to make an educated guess about acceptable practices.
>
> There's too much ambiguity here.  Follow Glen Zook's advice for the least
> trouble prone approach to replacing your finals.
>
>
>
>                                                           ---  CHAS
WA2DYA
>
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