TSSP: List Archives

From: Paul
Date: Tue, 24 Oct 2000 06:18:00 +0100
Subject: Re: [TSSP] The Q answer!?

Terrell W. Fritz wrote:

> The second 48 x 7.125 x 0.125 Sonotube gave an Fo of 144.79
> and a Q of 32.25!!  Yes, that really is 1/2 !

That's a very satisfying and convincing measurement!  

> I have no idea what is in the Sonotube but paper and
> wax/glue/plastic... but it is definitely high loss!!

Very high! I don't think it could be the wax or the paper -
you may recall I posted their loss factors to the list - and
they were modest. 

Is it a dielectric loss or a conduction loss I wonder? Maybe it
contains a fire-retardent or an antistatic that might be
soaking up the energy in conduction loss. Maybe the manufacturers
can reveal what went into it? 

Terry, at least you don't need to worry about how to suspend your
coil up in the air for that 1/2 wave Q measurement anymore!

If your low Q is entirely due to sonotube loss and if this kind of
loss is typical of sonotubes then the advice should be to not use
sonotubes for CW coils - the performance is reduced from what it
should be by a factor 4 or more!

I can see the 'Q chamber' is going to be busy for a while! 

Malcolm, what was the coil former used in your
Aug 96 Q measurements?

Cheers,
--
Paul Nicholson,
Manchester, UK.
--


Maintainer Paul Nicholson, paul@abelian.demon.co.uk.