[Swan] tube tester

[Greg Mijal]

A real simple way to do it is run two tubes at a time and insert a 
miliampmeter in series with each cathode lead. You will need two 
milliampmeters or a trick SPDT and one meter.  If the resting current (PA is 
on but no speech thru it, and the PA's tuned) is with 10 percent of each 
other.
Then set the pair aside and mark it as "matched"
Then run the pair in the radio for neutralization.  If the rig holds 
together for a couple of days without oscillating then you probably have a 
useable set of tubes.
Assumming they put out a reasonable amount of power.
73's
Greg
WA7LYO
Kinston NC
----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at verizon.net>
To: "Discussion of equipment manufactured by Swan" <swan at mailman.qth.net>
Sent: Saturday, May 19, 2007 6:01 PM
Subject: Re: [Swan] tube tester


> 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
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