[Swan] tube tester

[Maynard Wright]

One thing to keep in mind is that the dual tube Swans use a somewhat different 
tank circuit (PI or PI-L) than do the single tube Swans as the output of two 
tubes in parallel is lower than that of a single tube.  I wonder whether you 
might be able to compensate for this when using only one tube in the 350C or 
500C by using a dummy load of higher than normal impedance.  You don't want 
to operate these old sweep tubes with too high an impedance mismatch.

73,

Maynard
W6PAP

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On Saturday 19 May 2007 15:01, Kenneth G. Gordon wrote:
> On 19 May 2007 at 21:32, w7lrd at comcast.net wrote:
> > Greetings
> > I have about 30+ 6LQ6 and similar tubes.  They are all used (by me
> > over the years).  I want to test them in one of my 350C or 500c.  Can
> > I run each one "one at a time" and see what it loads up to and record
> > the results and perhaps match these tubes up.  Has anyone tried this?
> > For if I run two tubes at once the total Ip is just that the total,
> > and one tube may be working like heck and the other hardly working.
> > Any advice/sugestions.
>
> What you suggest above sounds OK to me, although with only one tube
> in place the neutralization will not be correct.
>
> However, more than likely, that won't be a problem on 80 meters. I
> would hesitate to do the testing at 10 meters, though, without correctly
> adjusting the neutralization with only one tube in place.
>
> If I were going to do as you plan, I would first do a complete and
> accurate neutralization procedure with only one tube in place, then run
> my tests up through 10 meters.
>
> Also, I would use the same socket for everything. Minimize the other
> variables. I prefer dealing with one variable at a time.
>
> I think it might be a good idea to measure the screen current of each
> individual tube also, since that would give you a good indication of
> possible gassiness or screen emission.
>
> Ken Gordon W7EKB