6146 Replacement

Brian Carling bcarling at CFL.RR.COM
Sun Oct 1 07:49:58 EDT 2006


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
parties involved.  This list and the City of Tempe are not responsible
for losses or misrepresentations of any kind.  Buyer beware!

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