EMRFD Message Archive 10177
Message Date From Subject 10177 2014-07-25 16:19:29 n2cx2001 WTB Autek VA-1 Gang,
I've owned and used the little brother to the VA-1, the RF-1, for over 10 years.
Alas I hesitated too long in springing for the VA-1 and now Autek has gone
Does anyone have one in good condition that they would like to sell me?
If so please email me directly at email@example.com and state the unit's
condition and asking price.
Joe E., N2CX
10230 2014-08-09 09:10:27 Joe Everhart Re: WTB Autek VA-1 All,
A couple of weeks back I asked if anyone had one excess to their needs.
Fortunately several folks responded and I'm now in posession.
My desire was to use the device to determine tuning of my Alex Walkham
loop. Unfortunately this instrument's oscillator is "pulled" by the hihg-Q
loop so getting a good reading at a desired frequency is difficult.
All is not lost however. There is a method for determining toroid core
characteristics in a paper by W1HIS on the YCC site at:
that uses the VA-1 to good account. I've got lots of -43 and -61 cores
that are co-mingled and this device and technique can help restore order.
Plus, I have many other bench uses for a simple instrument that can
provide R, X and Theta measurements at RF without a lot of hassle or expense.
Thanks to those who responded.
Joe E., N2CX
10233 2014-08-10 14:40:47 kerrypwr Re: WTB Autek VA-1 A good article; this link might be easier to open;http://www.yccc.org/Articles/W1HIS/CommonModeChokesW1HIS2006Apr06.pdf
The quick way to identify ferrite materials is to find the frequency at which Q=1 and compare that with the frequency at which the u" and u' curves cross in the Fair-Rite catalogue.
But, as described in the article, a choke/balun can be actually designed if complex impedance data over a frequency range is known; this contrasts with the more-usual amateur approach of just winding some wire onto some kind of toroid and hoping for the best.
It's useful to know the proportions of R and X in the impedance at various frequencies.