[Johnson] [Boatanchors] Valiant 6146 Question

[Dave Harmon]

+ 1000 on that Lee!!

Especially laughable is where he says the neutralization drifts......
Unless the internal elements inside the tube change position the neutralization will not change.

I don’t doubt that he had trouble with the VHF/UHF taxicab and trash truck Moto radios with non-adjustable FCC type accepted PA's.
He needs to re-write that paper and stop loading up every list at least once a week with this nonsense as relates to Amateur Radio.
There is a very small sentence in that paper that pertains to what the problem really was.
Essentially....it says that the tube mfgr changed the design of the tube and the Moto VHF/UHF PA's burned up because they had no adjustment for neutralization.
Most Amateur transmitters have adjustable neutralization as such can be properly adjusted.

Dave Harmon
K6XYZ[at]sbcglobal[dot]net
Sperry, Ok.


-----Original Message-----
From: boatanchors-bounces at mailman.qth.net [mailto:boatanchors-bounces at mailman.qth.net] On Behalf Of L L bahr
Sent: Wednesday, December 19, 2012 9:58 AM
To: whitebear1122 at comcast.net
Cc: boatanchors at mailman.qth.net; Johnson at mailman.qth.net
Subject: Re: [Boatanchors] Valiant 6146 Question

I have used 6146B and W tubes for years in many different boat anchors including a Valiant.  I never had a problem.  I consider the Zook paper flawed for ham HF transmitters.  All his findings seem to stem from Motorola VHF gear. I've used just too many W tubes in all kinds of Ham HF gear without a problem to believe his malarkey.  (I believe Zook believes what he wrote, but his experience had to do with non Ham VHF gear and not Ham HF gear).  I don't think it is a good idea to mix a B tube with either a 6146 or 6146 tubes, but other then that, it's been my experience you will not have a problem using B or W tubes. (You certainly can mix 6146 and 6146A tubes as the only difference is in the filament). Same goes for Collins S line equipment.  Guys will tell you Collins had to change the neutralization cap when they started using B tubes.  Not true!  It was changed because the original one was not right and adequate for it's application in the first place. If you look at tube data sheets you will find the specs between all these tubes are near identical.  Even RCA published the tubes are interchangeable.  The proof is in the pudding.  I think you are finding out for yourself there is no problem using B tubes in place of 6146 or 6146A tubes.  But again,  I'd certainly keep the same types together. Trust your own findings rather then someone elses goofy statements.

Lee, w0vt

----- Original Message -----



While I've read Glen Zooks 6146 article, and fine article it is too!, I wonder if anyone here has had any personal expereince with 6146 vs 6146B vs 6146W mixing and matching in the PA of the Valiant.  Over the weekend I repaired my Valiant and ended up replacing two of the three 6146's in the PA.  They only blew out after I had overstressed the transmitter while trying to tune up on 160m with an antenna and tuner that just wasn't going to take me there, so it wasn't the transmitters fault nor the tubes fault. I was my error.  I've since replaced the antenna and it tunes fine on 160m now.    After I closed up the transmitter,I then remembered the 6146 mixing and matching debate. I had not paid any attention to the 6146 flavors when put in the replacements.  It seems to be working nicely at least on 80m and 40m.  Haven't tried it on 20m yet.  150 watts output on CW.  I know I have 6146W's in the modulator and they work FB. 

  

I was just curious if others had actually had problems with the mixing and matching 6146's in the PA.  

  

I am also looking to buy some NOS 6146s, either straight, A's, B's, or W's.  I need some spares now. Out of my 4 spares, two are now in the Valiant, and the other two turned out to be weak.  They read 45 on the TV-7 (where 35 is minimum), but then quickly started dropping to the 20's before I let off on the button.  

  

Thanks. 73, Scott WA9WFA
______________________________________________________________
Boatanchors mailing list
Home: http://mailman.qth.net/mailman/listinfo/boatanchors
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Boatanchors at mailman.qth.net

List Administrator: Duane Fischer, W8DBF
** For Assistance: dfischer at usol.com **


This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html