[Heath] [Heathkit] 6146B Issues

Mon Oct 14 11:40:29 EDT 2013

JPG:

There are a lot of rigs, especially the Japanese transceivers, that were designed to use the 6146B/8298A.

The neutralization in the Collins S-Line and KWM-2- series is a bit different from the usual circuit.  The original neutralization circuit used a ceramic trimmer as the neutralization capacitor and, unfortunately, in well over 95% of the units, if the final amplifier tubes were replaced with the 6146B/8298A, or with a 6146W with a code date of after mid 1965, the ceramic trimmer literally "burned up".

The revised neutralization circuit that Collins "came up with", uses an air variable capacitor and there is a fixed capacitor and one resistor that are also changed.

Heath had a special run of General Electric 6146B/8298A tubes made to use in the HW-101 series transceivers.  However, those tubes were basically 6146A/8298 tubes.  Heath put a note in with those tubes which said that the only 6146B/8298A tubes that could be used in the HW-101 were those special tubes.

It was unfortunate that RCA used the 6146B/8298A nomenclature for those tubes.  RCA also initially said that the 6146B/8298A tubes were completely backwards compatible with the earlier versions.  Because of this, the military changed the 6146W tubes from the 6146A/8298 to the 6146B/8298A WITHOUT changing the nomenclature!  Unfortunately, the backwards compatibility did not work out in all situations.

In the commercial two-way radios, which are type accepted, those radios designed for the 6146 and 6146A/8298 tubes  would have to be modified to use the 6146B/8298A tubes.  Making such modifications violate the type acceptance!  However, especially Motorola, designed the later versions of the Motrac (the HHT "E" models, the LHT, and the MHT) to use the 8552/8032A/6883B tubes (the 12-volt equivalent of the 6146B series).

Glen, K9STH

Website:  http://k9sth.com

On Monday, October 14, 2013 6:09 AM, Bill Kuhn <BKuhn at kuhngroup.com> wrote:

Kenwood hybrids use 6146bs.

Sent from my Windows Phone
________________________________

From: Chris Kepus <mailto:ckepus at comcast.net> 
Sent: ‎10/‎13/‎2013 10:25 PM
To: 'Glen Zook' <mailto:gzook at yahoo.com> ; 'RAY FRIESS' <mailto:rayfrijr at msn.com> ; 'Gary H. Harmon, Jr.' <mailto:gharmon at idworld.net> ; heath at puck.nether.net; 'Heathkit2' <mailto:heathkit at mailman.qth.net> ; 'Heathkit3 LIST' <mailto:heathkit at yahoogroups.com> 
Subject: Re: [Heathkit] [Heath]  6146B Issues

Glen, 

Your article on the 6146 family is very informative and helpful.  However,
it begs the question..what to do with all those 6146B/8298A's? 

Your article stated that Collins "figured it out" for the later S line
transmitters (amazing what necessity fosters).

I wonder if anyone has compared the Collins neutralization circuitry for the
early transmitters to the latter ones?   Could the later S-line approach
(whatever it is) work with other 2X 6146 rigs so that they would be "happy"
with the B's?  

Are there any other known 2X 6146 rigs that can run B's without problems?

Glen.anyone?

73,

Chris

W7JPG

From: Heath [mailto:heath-bounces at puck.nether.net] On Behalf Of Glen Zook
Sent: Saturday, October 12, 2013 9:26 AM
To: RAY FRIESS; Gary H. Harmon, Jr.; heath at puck.nether.net; Heathkit2;
Heathkit3 LIST
Subject: Re: [Heath] [Heathkit] 6146B Issues

The DX-35, DX-40, and the DX-60 series "load down" the grid circuit.  This,
in turn, requires considerably higher output from the driver stage.  As
such, Heath did not neutralize those transmitters.  With the "loaded down"
grid, the 6146 in the final amplifier is much less likely to "take off" and
neutralization is not usually required.  In most cases, the 6146B/8298A or
6146W tubes will work fine.

Of course, there are always exceptions.  As such, I will not say that the
later tubes will work in every DX-35, DX-40, and DX-60 series.  However,
there is a very good chance that the tubes will work fine.

Glen, K9STH

Website: http://k9sth.com

On Saturday, October 12, 2013 10:48 AM, RAY FRIESS <rayfrijr at msn.com> wrote:

Glen ...   question.
Does this apply as well to the simple Heathkits like the DX 40 and DX 60?
I don't recall off hand that those simple ones require or even have
provision for neutralizing.

Ray  wa7itz

  _____  

Date: Fri, 11 Oct 2013 18:46:40 -0700
From: gzook at yahoo.com
To: gharmon at idworld.net; heath at puck.nether.net; heathkit at mailman.qth.net;
heathkit at yahoogroups.com
Subject: Re: [Heath] [Heathkit] 6146B Issues

There is no list.  However, the 6146B/8298A and the 6146W tubes require
different neutralization and most of the Heath SB-Line equipment are very
"iffy" in whether or not they can neutralize.  Some units seem to work OK
but even more have problems.  One can modify the neutralization circuit so
that the transmitters / transceivers will neutralize.  However, for "plug
and play", one really needs to use the 6146, 6146A/8298, or 6293 tubes,
especially if they have problems neutralizing the tubes.

There are those who violently disagree with my article on the 6146 family of
tubes:

http://k9sth.com/uploads/The_6146_Family_of_Tubes_1.pdf

However, over the years, I have literally seen well over 10,000 transmitters
that use the various 6146 family of tubes and my observations are outlined
in the article.

There are those who say that they have used the 6146B/8298A or 6146W in
transmitters that were designed for the 6146 or 6146A/8298 without any
problems.  I do believe them.  However, I have received notice from a LOT
more people who say that they have had problems and went back to the earlier
tubes.  It seems to be how the individual tolerances of the components "add
up" as to whether or not the later tubes work.

I have worked on individual transmitters, of exactly the same model, with
serial numbers within 10 of each other.  With those transmitters 1 was happy
with the 6146B/8298A and the other 2 were very unhappy.

Glen, K9STH

Website: http://k9sth.com

On Friday, October 11, 2013 5:13 PM, "Gary H. Harmon, Jr."
<gharmon at idworld.net> wrote:

I seem to remember there are some pieces of Heathkit that are not
HAPPY-HAPPY-HAPPY with 6146B tubes.  Is this a myth or is there a list of
pieces that prefer to not see a 6146B?

Thanks and 73,  

Gary H. Harmon, Jr. - K5JWK

6003 Archwood

San Antonio, TX 78239-1504

210.657.1549h / 210.884.6926c/t

"Retirement means every day is a Saturday except Sunday"

http://www.grissomroadcoc.org <http://www.grissomroadcoc.org/> 

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