17 foot whip / 5.6M Telescoping Whip like the MFJ-1979

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by K7JOE, Jun 16, 2021.

ad: L-HROutlet
ad: l-rl
ad: l-BCInc
ad: l-gcopper
ad: abrind-2
ad: L-MFJ
ad: Left-3
ad: QSOToday-1
ad: Left-2
  1. K7JOE

    K7JOE Subscriber QRZ Page

    MFJ sells a 17 foot telescoping steel whip with a 3/8 x 24 fitting for $70 plus sales tax and shipping. Getting one to my door is nearly $90 all-in. I've used one as an option for a very effective "stationary" mobile antenna for the higher bands -- allowing for a true 1/4 lambda radiator for optimal efficiency -- no lossy loading coils or need for cap hats. But the antenna, for what it is, is expensive.

    I have now found an alternative for half the price of the MFJ that is almost the same and works great. The only catch is that Sonny gets these made as part of a "buddi-pole" type antenna system and for the domestic market - so the mounting is not SAE thread 3/8 x 24 thread but rather metric thread M10 (metric, 10mm).

    It is fairly easy to modify a typical mobile antenna bracket / mount by replacing the 3/8 x 24 "barrel" with a M10 barrel. To do so, I replaced both the bolt and "barrel" with M10 hardware. The collar washers fit just fine and I am up and running. I don't think you could do this with an SO239 fitted mount, but the "solder lug" style is easy to change.

    Note that the antenna is an exact same material, same length and diameter and number of sections (14 sections) and probably the same manufacturer as the MFJ variant, except for the brass base screw. The antenna handles 500W PEP no problem with no signs of heating anywhere. It would be pretty easy to take a 3/8x24 collar and weld a M10 nut to one end of it ...which would allow it to be used in a variety of 3/8 x 24 antenna mounts such as a ball mount, etc. Or you could buy an adapter from a car parts shop.

    Here is a link for those interested:
    https://www.ebay.com/itm/265087608788

    there are a few other cool gadgets from this seller -- an interesting loading coil and a shorter whip that still is over 9 ft long.
     
    Last edited: Jun 16, 2021
    KK4NSF, AK5B and K0UO like this.
  2. WA7ARK

    WA7ARK Ham Member QRZ Page

    Some where around here I have a 3/8-24 bolt welded head-to-head to a M10 metric bolt. I have a Mig welder and know how to weld (sort of;)) , but I made that exactly to solve your problem... The bolts (and internally threaded bushings) are available at our local Ace. Take them to anybody that can weld...

    btw, I own one of the long WebsterBand Spanner pull-up-whip mobile antennas. I sometimes screw it onto the isolated, coax-fed 3/8-24 stud I put on the ladder of my RV trailer... Easy, quick, if not highly efficient way to get on any frequency from 3.5 to 30MHz (after arriving at the campsite).
     
    Last edited: Jun 17, 2021
    AK5B, K7JOE and K0UO like this.
  3. K0UO

    K0UO Platinum Subscriber Platinum Subscriber QRZ Page

    Thank you good info/ I like using those whips on my RV when parked.
     
    AK5B and K7JOE like this.
  4. K8JD

    K8JD Ham Member QRZ Page

    So this telescoping ant would be a QW on 13756 kHz, I think you would shorten it a bit for higher bands, keep a tape measure close. But you can't expect to go lower in freq .
    "Lossy" loading coils work great for that.
     
  5. K7JOE

    K7JOE Subscriber QRZ Page

    Yes. Just collapse it a little and watch vswr dip tune anywhere 20M up to 2 meters (19 inches fully collapsed). No need for a tape measure. Mark the antenna with a sharpie for easy bandhopping

    Yes on the full size Webster bandspanner. Have one of those too. Totally agree. Great approach !!!

    For lower QRG i can deploy the bug catcher or have made a home made coil to cover, say, 40M. Fairly easy to do.
     
    Last edited: Jun 17, 2021
  6. WE4E

    WE4E Premium Subscriber QRZ Page

  7. KK4NSF

    KK4NSF Ham Member QRZ Page

    making an adpter for using either variation of the 17ft collapsable whip is easy-peasy. I'v e got the MFJ variety, and have made all sorts of adapters for it using standard hardware store parts, and a suitable tap or die as the case may require.

    It's a very handy antenna, since you can mate it up with a suitable coil and radials.... and use it on anything from 40m up to 6m. It collapses down to a nicely portable size, too. I use mine for field operating.... like parks, islands, and so forth.
     
    AK5B likes this.
  8. AK5B

    AK5B Ham Member QRZ Page

  9. KK4NSF

    KK4NSF Ham Member QRZ Page

    AK5B likes this.
  10. AK5B

    AK5B Ham Member QRZ Page

    I also have a couple of the MFJs that I've used atop screwdrivers and as a adjustable dipole in the past---and have recently been toying with the idea of getting a third so I could rig up a tripod mounted elevated 10-20m vertical for my seaside portable fun.

    All one needs for something like this is three of these whips and a hamstick dipole bracket with a "mirror mount" or piece of angle stock+ PL259 coupling mounted to it (and a clamp or way of mounting everything on the tripod or other easy support).

    While I take forever with most of my projects I will post a thread once I get around to this later this summer. I already have a tall vertical I built for 17 and 20 meters portable stuff---but something collapsible and adjustable like my 3-whip idea could be an improvement in the ease and flexibility department for sure.

    My thanks to Joe for his discovery, too---it even looks like better quality than the junk from Mississippi! (one of my 1979s has some loose sections that don't want to stay extended).

    73,

    Jeff
     
    KK4NSF likes this.

Share This Page

ad: AlphaRF-1