6146 Replacement

[Brian Carling]

Thanks guys - this has all been very informative anmd I have 
kept notes on it for future reference.

> On 30 Sep 2006 at 14:20, Bill Coleman wrote:
> 
> > Here's the definitive article on this:
> > http://www.members.tripod.com/NRWILLIAMSON/t6146.txt
> 
> In Glen's article referenced above, he says that to his knowledge, 
> Heathkit never mentioned using the 6146A over the 6146B.
> 
> However, on the back of my recently restored HW-101, there is a 
> sticker which obviously came with the kit that says something very 
> close to, "Use 6146A type tubes ONLY in this transmitter"
> 
> Now, when I restored this HW-101, one of the original 6146s developed 
> some sort of interesting internal short that burnt out the 0.22 ohm 
> cathode metering shunt. 
> 
> At the time, all I had was a pair of NIB 6146Bs, so, with much fear and 
> trepidation, I installed them, and VERY carefully neutralized the rig.
> 
> Checking that over several days of operation, everything seemed to be 
> stable and the rig works very well.
> 
> However, I recently discovered that when I tune the rig up on 40 
> meters, the GFCI associated with our basement refrigerator ALWAYS 
> trips.
> 
> Furthermore, I also recently discovered that with the outer cabinet off, 
> on 40 meters only, under certain conditions the final oscillates and 
> draws excessive plate current.
> 
> Thus, as soon as I can obtain a set of 6146As, the 6146Bs will be, 
> forthwith, removed and the "As" installed in their places. Then I will 
> neutralize the rig as I did before.
> 
> I thank Glen Zook for his valuable information. In the case of the DX-35 
> or DX-40, this may not be a problem, since, as Bill Coleman mentions 
> they are running in Class C. Also, the grid circuits of those rigs are 
> purposely designed to be low impedance and this also contributes to 
> those rig's stability.
> 
> However, one must be careful and watchful if one has to use a 6146B 
> where a 6146/6146A was original equipment, and if anything "funny" 
> appears, go to the older tube.
> 
> Ken W7EKB
> 
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Products bought, sold or traded here is the responsibility of the
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for losses or misrepresentations of any kind.  Buyer beware!

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