[600MRG] Q meters

[Frank Lotito]

Measuring antenna Q via a bandwidth method is definitely a means to deduce Q, but it is "total system Q."  Its difficult to deduce the Q of a particular element within the system using a total system Q measurement technique.  A suggestion - to keep from making an error that I made and will not forget - Make sure the inductor you are measuring is suspended high and dry when its being measured.  A rule of thumb, keep the inductor on or better yet two diameters away from any conductive structure, such as a metal topped work bench.   The same rules apply when mounting the inductor in an enclosure.  As we all know, toroid and E-core inductors are a darned more forgiving.  Their external filed is only a small fraction of what an air-core or ferrite / iron powder rod inductor is.  

73 Frank K3DZ / WH2XHA

________________________________________
From: 600MRG <600mrg-bounces at w7ekb.com> on behalf of Laurence KL7 L <hellozerohellozero at hotmail.com>
Sent: Sunday, September 27, 2015 8:13 PM
To: 600mrg at w7ekb.com
Subject: Re: [600MRG] Q meters

or 3 hrs 27 mins to Seattle at 540Kts :-)

> Date: Sun, 27 Sep 2015 15:52:36 -0800
> To: n6lf at epud.net; 600mrg at w7ekb.com
> From: kl7uw at acsalaska.net
> Subject: Re: [600MRG] Q meters
>
> Rudy,
>
> Good idea if you live in the lower-48 with several flea markets a
> month to chose from.  We only have three per year up here and they
> are now over for the year.  One is local (we held it two weeks ago)
> there were no Q-meters at it.  I did score a CE-5 Cushman service
> monitor which is fully functional for $50.
>
> The other flea markets are 230-mile away (5-hour drive) or 450-mile
> drive (9-hours) and also unlikely to have this stuff.  But you can
> buy all the FT-101E's you might like ;-)
>
> Otherwise its a four hour drive to the airport, and 3-1/2 hour $900
> flight to Seattle and car rental and hotel charges and eating in
> restaurants to get to any of your flea markets...call it $1500
> min.  Then hope you don't pay excessive baggage fees getting one back.
>
> But maybe I could find one on e-bay and only pay $250 shipping to get
> it up here.
>
> Ah did you mean to write HP432A as that is a mw power meter and I
> already have one.
>
> My base coil is built so how is one supposed to improve it?  I used
> my MFJ analyzer to resonate the antenna and then tapped the bottom to
> get a match to 50-ohm coax.
>
> Can't I deduce Q from measuring antenna bandwidth?  Its about 5-7 Hz.
>
> 73, Ed
>
> At 02:44 PM 9/27/2015, Rudy Severns wrote:
> >Old Boonton/HP Q-meters (160A or 260A) should go for $50-$100 at flea
> >markets.  The newer but well used HP4342A Q-meters should only be $200 or
> >so.  EBay is of course the high priced place to look but I saw few under
> >$100 in a quick check.  Keep your eyes open and shop around!  Once you have
> >one of these in hand you can really work on improving your coil Q's and also
> >having the correct numbers for analysis.
> >
> >
> >
> >In most amateur antennas efficiency will be dominated by loading inductor
> >loss.  Knowing and improving the Q is the key to efficiency once you have
> >the vertical as high possible with as much top-loading as possible.   Of
> >course that's at 630m, at 2200m it will be overwhelming the case.
> >
> >
> >
> >73, Rudy N6LF
> >
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>
> 73, Ed - KL7UW
> http://www.kl7uw.com
>      "Kits made by KL7UW"
> Dubus Mag business:
>      dubususa at gmail.com
>
>
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