Monthly Archives: October 2015

A special testimonial

Many thanks to Art, W6GRT, who had this to say about the matchbox:

Hi Ken,
Great device!  I enjoyed it this afternoon for the first time.  I used my Youkits
HB-1B, Elecraft QRP ATU, followed by 25 feet of RG-8X, your matchbox, and
64 ft of wire sloping up my back hill tied to a plum tree.
First QSO, Simpsonville, South Carolina, followed by Redmond, WA.  I hope you do
very well with this product.  You and Begali keys have the best customer service
in our hobby.  I wish I could say the same for every ham radio product.
God Bless you and 73,
Art, W6GRT, Santa Clarita, CA

Antenna analyzer results for end-fed matchbox

EFMBA-newSo, I get the question all the time, “Can I use the matchbox without a tuner?” My answer is always this: For best results, you are going to need a tuner. Why? Simple. With an end fed antenna, the impedance is always going to be high and as you change bands, it’s going to vary all over the place. It may or may not fall into a range where the matchbox can deliver an impedance that your rig’s internal tuner can tolerate. Then again, it may under certain conditions and with different rigs. I realize that’s rather a vague explanation, so I took out my trusty MFJ-259B SWR analyzer, hooked up the matchbox with 50 feet of #18 wire, 16 feet of #20 counterpoise and 50 feet of RG-58 coax. The antenna was deployed as a sloper with the far end at about 12 feet over a tree limb and the fed end at about 3 feet off the ground. Here’s what I found:

160m (1.9 MHz): SWR=10.5
80m (3.75 MHz): SWR=5.2
40m (7.150 MHz): SWR=4.4
30m (10.125 MHz): SWR=2.8
20m (14.175 MHz): SWR=4.4
17m (18.118 MHz): SWR=2.6
15m (21.225 MHz): SWR=2.3
12m (24.940 MHz): SWR=1.8
10m (28.85 MHz): SWR=2.2
6m (52.0 MHz): SWR=2.5

It’s pretty obvious from these numbers that in my case, I could probably get by on 30m and 17m thru 6m without an external tuner. Your mileage will vary. And even though these SWR numbers seem to look OK, there is much more to SWR than just a number. This article will give you a better understanding of the subject.

de W4KGH