Shakespeare's ART-3, check your transmitting power!
Apr 26, 2006
I may be naive—I don’t have much experience with testing tools—but Shakespeare’s ART-3 impressed me. In this picture, bigger here, that VSWR reading well into the red demonstrates something I’d suspected but wasn’t positive about…the old antenna attached to the Icom 504 may look OK but it must be pretty pooched inside. VSWR, by the way, stands for “voltage standing wave ratio” though Shakespeare more reasonably terms it “antenna efficiency”. Interestingly the meter showed the Icom and other of my test radios transmitting at a mere 17 watts with this same antenna, but pumping out a full 25 watts with a VSWR of only 1.25 (a mere loss of 2% according to the table on the meter face) when well wired to a decent antenna. Antennas really make a performance difference, as does a good power supply. The $90 (retail, though I don’t see a place to buy one online) ART-3 can also generate a tone on Channel 72, thus providing a simple reception test. Note that you do need to provide your own short patch cable between the meter and radio, annoying, but it is smartly designed so that it can be used portably with an internal battery or rigged permanently with wired 12v power.
Posted by Ben on April 26, 2006 3:59 PM
Look interesting. I Googled it and found it for $60 at Boatfix.com. I'd really like this for my SSB!
Posted by: Russ at April 26, 2006 11:16 PM
If that is a VSWR reading, something is terribly wrong. Are you sure you set the meter properly for the VSWR measurement. It looks like you need to adjust the sensitivity using the knob and the SET position.
Really, Jim, that is the VSWR. I adjusted sensitivity to the Set line before measuring, per instructions; also got similar results with other radios and same antenna, much better results with same radios and new antenna. I had noticed many months ago that this antenna doesn't work well at all! Maybe it's something as major as a broken lead inside the coax?
I bought my meter at Fisheries Supply in Seattle.
It is a useful tool, and comes with the jumper cable.
Fisheries Supply also carries the Morad "Hot Rod" antenna. This is a MIL spec VHF Antenna much used by the commercial fleet which will cost about $150 as you need addapters to mount it.
I also recommend using soldered connectors with antennas, this saves a lot of grief.
I am retired and have no interest, except in gear that works.
Posted by: Pat Harman at April 27, 2006 5:10 PM
VSWR can be calculate by the following:
F = Forward power
R = Reflected Power
VSWR = (F+R) / (F-R)
If everything is ideal you have no reflected power, its all going out the antenna and you have F/F = 1
It all goes down hill from there :)
Posted by: bob at April 27, 2006 5:46 PM
This would be great for SSB, anyone got a good way to test SSB antenna or longwire antenna?
Posted by: James at June 11, 2006 10:09 PM
I noticed that the ART-3 has a frequency range of 155-158 Mhz. I need to us this at the frequency of 158.770. Just wondering if the accuracy will be degraded because it is on the extreem high end of the frequency range? I couldn't tell if there are any interchangeable crystals.
Posted by: Bart Browning at December 17, 2007 8:02 PM