[TowerTalk] Bazooka 1/4 wave balun

[Michael Tope]

This discussion brings up a good question. What is the best what
to make accurate inductor Q measurements? I understand that 
there are Boonton Electronics Q meters out there. How do those
compare with other techniques like using a vector network 
analyzer?  I see people talking about Q's of 400 to 800 for 
HF loading coils. How easier or hard is it to measure Q's in that
range? 

Thanks,

Mike, W4EF......................................

----- Original Message ----- 
From: "Tom Rauch" <w8ji at contesting.com>
To: "Jerry K3BZ" <k3bz at arrl.net>; "Jim Lux" <jimlux at earthlink.net>
Cc: <towertalk at contesting.com>
Sent: Wednesday, July 06, 2005 11:56 PM
Subject: Re: [TowerTalk] Bazooka 1/4 wave balun


>> One way is if you have an air core inductor that you can
> measure the loss
>> of (say you've got it resonated with a capacitor at 14
> MHz). Shove the
>> suspect hunk of plastic in the middle and see if the Q of
> the coil
>> drops.  If not, you're good to go.
> 
> Space winding an inductor reduces turn-to-turn capacitance
> and increases inductor Q. Fill the area between turns in
> with a dielectric and Q decreases.   That's because
> capacitance and circulating currents increase. Knowing that,
> how do we quantify how much Q loss is caused by an increase
> in turn-to-turn capacitance as a dielectric is brought near
> or against the turns and how much is lost through power
> dissipation in the dielectric? How many people can measure
> Q?
>