6146 Replacement

[Bill Coleman]

On Sep 29, 2006, at 9:40 PM, W5EUQ wrote:

> Okay guys.  Question.  Tell me again WHY to not use a 6146B in a  
> DX-40?

The 6146B is a different tube. It isn't just a 6146A with a higher  
plate dissipation. It has completely different inter-electrode  
capacitances.

> I know the 6146B's are not as good as the 6146A's, for example.

Actually, in a correct design, the 6146B is more capable than the 6146A.

>   I also understand they are built somewhat different to the A  
> model.... and may be the characteristics are different.....

That's the key.

> however, I have put two 6146B's in my DX40's(actually both DX40's  
> came with B's in them)  and I get almost 50 watts output... So I  
> put some 6146A's in both rigs and got the same power, same  
> everything.......  so do the B's self destruct, not last as long,  
> oscillate or what?    Neutralization changes so that it oscillates?

DX-40 is a class C amplifier, so it's not so critical, I suppose. For  
that matter, you could put it a 2E26 tube, and it would work, too.

> So tell me one more time...but please tell me what is fact, not  
> what is "wives tales"....   I promise to pay attention this time...

Here's the definitive article on this:
http://www.members.tripod.com/NRWILLIAMSON/t6146.txt


Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901

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