[Boatanchors] 6146 question

[Bill Cromwell]

Hi,

Solid state indeed:) My own results but limited to fewer transmitters match Pete's. If you don't like microprocessors and menus in your rig I can recommend the Atlas line and there is always the homebrew option.

73,

Bill  KU8H

> On Jan 29, 2024, at 3:40 AM, manualman at juno.com wrote:
> 
> When I picked up a HW-101 at a flea market for $20 years ago, it didn't
> have any final tubes. Brought it home and leaned it up, put in a pair of
> 6146B's (they were handy on the work bench) and the HW-101 worked fine
> from the get go all the way to 10 meters. When I finally sold the rig, to
> make it "original" I put in a pair of 6146A's. Saw no difference in
> performance and the various transmitter knob settings for various bands
> using the 6146B's had been recorded and the settings were almost
> identical on every band using the 6146A's.
> 
> My Apache, which I built, was switched over to 6146B's in the 70's and
> has worked fine all the way to 10 meters on AM and SSB(SB-10 was put in
> operation a year or two after I built the Apache). The Apache had a very
> rudimentary neutralization (a stiff piece of wire that struck through the
> chassis and you moved it between the two final tubes). No oscillations,
> no funny squeals. 6146B's are still in the rig and I still use it on a
> regular basis.
> 
> My Valiant had three 6146B's in the final, and two 6146A's in the
> modulator. Those were the tubes I had handy when I got the Valiant that
> only had weak 6146's in it. I only paid $70 for the Valiant so I didn't
> complain. No problem with the B's all the way to 10 meters. Sold the rig
> several years ago but actually heard it on 40 meters AM several weeks
> ago.
> 
> This issue of the 6146 family has come up numerous times over the years.
> Several years back, I made a comparison chart of the inter electrode
> capacitance of the various 6146 tubes. In some cases, the capacitance
> values were identical between tubes or the variation was maybe a 1/2 pf.
> I have no idea what I did with the chart and have no ambition to pull the
> specs for various 6146's and regenerate it again.
> 
> This 6146 family P&M will probably go on as long as the tubes are still
> available for sale used or otherwise. Personally, I really don't care,
> since in 50 plus years , I've never found a valid reason or equipment not
> to use 6146B's in place of 6146's or 6146A's.
> 
> Back over the years, some have had "bad" experiences and pointed to the
> tubes. Maybe the tubes were the problem but maybe the real problem was a
> circuit design fault. Life moves on. If it continues to bother you, annoy
> you, makes your daily life miserable, or gives you digestive issues,
> maybe you should get a solid-state rig.
> 
> Pete, wa2cwa
> 
> 
> On Sun, 28 Jan 2024 22:14:47 -0500 "Paul Christensen" <w9ac at arrl.net>
> writes:
>> Back in 1973, I had horrid results when changing from 6146A to a 
>> 6146B tubes in a Heath HW-101.   With the B tubes, I couldn't 
>> neutralize the PA and get stable 15m and 10m performance.  On those 
>> bands, the transmitter would "take off" as the mic gain/carrier 
>> control was advanced while simultaneously producing a high pitch 
>> screech from the PA.   I tried multiple sets of B tubes and had 
>> identical results.  Switching to a new set of A tubes solved the 
>> problem.  Back then, a pair of 6146 tubes from our local wholesaler 
>> was about $10.  As I recall, Heath published a service bulletin with 
>> a warning to only use 6146A tubes.
>> 
>> Given this experience, there's no way I'd consider all versions as 
>> universally interchangeable.  Possibly better results would have 
>> been attained with a slightly larger variable neutralizing cap value 
>> but that's not something I would have considered at age 13.  That 
>> said, I believe there's value in the work reported by K9STH and 
>> K9AXN.  
>> 
>> Paul, W9AC        
> 
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