[Boatanchors] Valiant 6146 Question

[Jim Wilhite]

One thing most of us forget is that when you change final tubes you should 
neutralize them in any or all transmitters.  Each tube, no matter the 
manufacturer will have very small differences.  Neutralization is not all 
that critical on 160-40 but when you are at 14 Mc or above it should be done 
especially for 10 meters.  By doing that you minimize the potential for 
troubles with the B or W tubes.

The problem that Glen cites was present is some Collins HF gear.  Collins 
produced a retrofit kit for the transmitter(s) in question so the later B 
version of the 6146 would not pose problems.  If I recall it was a larger 
neutralization cap but it has been several years.

Jim
W5JO


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



>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.
>
> > Thanks. 73, Scott WA9WFA
>