MFJ 1729 Dual 2M/440 antenna

[blackbelter]

Any input regarding this antenna would be appreciated.

Thanks,
KI4NRD

[drosenstein]

I have used one for a short time. It seems to pretty sensitive but I have not been impressed with it transmit at on 2m. I haven't tested it much yet though.

Do you have a specific question?

Dave

[kf4lne]

its a 1/2 over 1/4 on 70cm so it does have *some* gain but not a lot and its a 1/4 wave on 2m, so its unity gain. I have played with those at ham fests and on 70cm they are an improvement but arent all that for 2m, they are also way too thin and small to be taken seriously considering I have always used commercial antennas from Anatenna Specialists and maxrad, but the MFJ does work.

[kb2vxa]

Hi Black and Belter,

Getting real with those gain figures it's unity on 2M and approximately 3dB on 70cM, nothing special. It's a common design made a bit more cheaply than say, a Diamond and frankly I wouldn't touch it with a ten foot SN* because of it's flimsy mechanical construction. Hit a low hanging tree branch and that coil gets a permanent bend and trying to straighten it out will surely detune it.

* SN to SR is the Polish callsign prefix block and a lousy joke.

Now getting down to brass tacks, a quarter wave whip for 2M has nearly the same gain figures and being 20" long and far more rugged that would be my choice if I weren't interested in more gain. Yup, it's 3/4 wave on 70cM which provides a 50 ohm match and approximately 3dB gain over a quarter wave.

Now here I go having fun with Dan again;
"its a 1/2 over 1/4 on 70cm so it does have *some* gain but not a lot and its a 1/4 wave on 2m, so its unity gain."

Uh, if I remember right 1/2+1/4=3/4 but I could be wrong. The 1/4 wave helical delay line makes it a colinear rather than a straight 3/4 wave and that raises the 90 and 180 degree (current) points up the radiator giving it slightly more than 3dB gain while the straight 3/4 wave gives sligtly less. That's why the qualifier "approximately" in my preceeding remarks. There's no point quibbling over a few tenths of a decibel so they're essentially the same.

BTW the ASP667 is the closed coil version of the same antenna so there goes your theory right out the window. (;->) OK OK, don't hit me, the ASP is rugged as all get-out and the spring doesn't mind getting all bent out of shape.

[blackbelter]

WOW, thanks for your indepth response. I simply wanted to utlilize it with my HT reaching the nearby repeaters. This antenna will be used as a base station add on (just hit a repeater 20 miles from my house with this antenna).
Once again, thanks
73,
Bob
KI4NRD

[blackbelter]

MFJ-1729
Power*Gain 144/440 MHz Magnet Mount Mobile Antenna



Click the thumbnail for a full-size picture.

MFJ-1729

MFJ's Power Gain is ham radio's most powerful dual band magnet mount mobile antenna!
It gives you outstanding gain on 440 MHz and 2 Meters. Low SWR lets you rig deliver full power safely. Get a whopping 2.6 dB gain on 2 Meters and 6.3 dB gain on 440 MHz.
Perfect for dual band mobiles or HTs. Free BNC handheld adapter. Handles 300 Watts PEP.
MFJ's exclusive 27 1/2 inch stainless steel SlimLineRadiator minimizes wind vibration for less SWR flutter -- gives you longer range and better readability. Includes 15 feet of coax with PL-259 connector, heavy duty magnet mount with scratch resistant rubber guard.

[intrepid97]

I have that exact antenna and have had NO problems with it,It has been SMACKED against tree limbs and has yet to bend,break, or anything harmful happen to it at all.

To those of you who HAVE NOT had ANY experience with that antenna,I think you should reserve judgement until you have had the chance to try it out.

As for performance,I can hit the repeaters in my area with no problems at all,So from a person,Like myself,Who does have experience with that antenna,I will say it is VERY well worth every penny I paid for it.