MFJ 1622 Question

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KN4ICU, Feb 12, 2018.

ad: L-HROutlet
ad: l-rl
ad: l-assoc
ad: Left-2
ad: MessiPaoloni-1
ad: Subscribe
ad: Left-3
ad: L-MFJ
  1. KN4ICU

    KN4ICU Ham Member QRZ Page

    Well.. I tried putting up a dipole... Won't fit on the property. Tried putting up a 64 ft end fed, but not enough room. I am wanting to just get on the 40m band at the moment for CW and listen to other bands. I am starting to think the MFJ 1622 apartment antenna might have to be a viable option for what I have to work with.

    Any thoughts on how this could work well (for a compromise). I'm thinking of replacing it's antenna with a 10ft whip and putting it up on the balcony around 13 ft up. I do have an antenna tuner.

    Please before saying "just put up a stealth antenna, dipole, etc." let me again repeat there is no room.

    Before saying "get a loop antenna". They are too expensive at the moment.
     
  2. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Any antenna you get up is miles ahead of the perfect antenna that you can't actually deploy.

    The MFJ 1622 apartment antenna is basically a base loaded, adjustable tap, short vertical. Electrically it's very similar to a mobile Screwdriver antenna without the remote tuning capability or a mobile, base loaded Bugcatcher with a moveable inductor tap to select operating frequency. Antennas like this can certainly work, it will need some form of RF Return in the form of counterpoise, radials or something else to serve as the other half of the antenna, IOW to serve the same role as the metal vehicle chassis in a mobile deployment. That could be metal railing on your balcony, some wire hung down off the deck, ground screening on the balcony floor, elevated radials or something else, but there has to be something serving as the other half of a vertical like this.

    Personally I'd homebrew something like this rather than pay a hundred bucks for it. I've built a number of similar antennas for mobile and rapid portable use and one very inexpensive way is to pick up a center loaded CB antenna like you can find at truck stops, replace the 11 meter loading coil with a higher inductance home wound coil, use an alligator clip to select the coil tap for each band.

    These are good starting points for a homebrew tappable bugcatcher: https://www.newegg.com/Product/Product.aspx?Item=0H3-000W-00048 I stop at truck stops on road trips and have purchased several of these over the years when they're on sale, typically for $10 to $20 if you find a decent sale. Add a clamp on mount like this and some coax and you're in business: https://www.ebay.com/itm/Workman-RV...047285&hash=item3afea9908f:g:41oAAOSweLBaY5tB

    The loading coil is held in place by a pair of allen wrench set screws accessible when you unscrew the bottom mast and whip. Remove the coil and replace it with a coil of around 15 to 20 turns of stiff wire on a 3" to 4" coil form (could be wound on PVC pipe, could be wound using the grommet strip method for a low loss air coil: https://www.eham.net/articles/23124 or methods described here: http://www.arrl.org/files/file/Technology/tis/info/pdf/9708033.pdf) the specific inductance isn't critical as long as you wind enough turns for the lowest frequency band you want to cover as you'll use the clip lead to select the best tuning for given bands. Replace the short top whip with something like a 54" to 102" whip and you should easily be able to work 40m through at least the lower edge of 10m. If you go longer with the top whip you'll lose the ability to tune 10 meters and if you want to work 80m you can do so with a larger loading coil, it won't be very efficient on 80m at such a short overall height but it can get you on the air with the same tradeoff mobile operators make to work low bands.

    Anyway, the MFJ 1622 can certainly work, expect performance similar to a loaded HF mobile antenna because that's basically what it is. But if money is tight, you can homebrew pretty much the same thing for a fraction of the cost.

    And I know you said you tried fitting a dipole, but you can shorten the necessary space by running a loaded or trapped dipole. Something like this fits in a loss less space then a full half wavelength 40m dipole: https://www.dxengineering.com/parts...fu4JPUbnWjtOJHs-pZrMg2SZa8Wx2JKBoC9loQAvD_BwE
    It's also about half the price of the MFJ apartment antenna and of course can be installed inverted-V style to save even more space.

    Lots of options and sure we love to go on about the most efficient antenna that works within a given set of limits but any reasonable antenna that gets you on the air is better than no antenna.

    Good luck,
    -Dave
     
  3. K8JD

    K8JD Ham Member QRZ Page

    40M Antenna
    Is there a way to put up a 66 ft dipole that is angled around a bit (not totally foldled back close to it's self though). I have seen attic dipoles shaped like a flat "Z" work fairly well. :)
     
  4. KC3GHK

    KC3GHK XML Subscriber QRZ Page

    I've been reading most of your questions here on the forum and would encourage you to not give up and get a can do attitude and be an experimenter! Nothing will work if you don't try it and rely on the forum to give up. Just try zig and zaging your antenna even if it's close to a gutter. I have had antennas close to aluminum siding and gutters and they received and "GOT OUT" maybe not "GOOD" but don't let perfect be the enemy of getting on the air and enjoying the hobby. I started with end fed antennas completely hidden in trees and touching trees 100% and they "WORKED"! I then added different numbers of radials or counterpoises HIDDEN until they "WORKED" better. I then made them longer all the while reading about what others in restricted situations were doing and getting more and more ideas as I read more and more. The internet and GOOGLE are amazing resources! I have used black push up fiberglass poles to hold the center of antennas IN against trees (again hidden) with the ends fairly low and hidden in other trees. They WORKED. I have used aluminum vertical antennas up into a huge canopy of a tree with various radials (counterpoise) hidden around my very small back yard and by golly it WORKED! Experiment and be an AMATEUR hobbyist and don't give up, it's fun to make stuff work even if it's not perfect! I have talked to Hams with antennas only feet off the ground and we had fun talking to each other and sharing ideas about making things better! Read about BalUns and UnUns and counterpoise and radials and end feds and inverted end fed L's and you'll be amazed at what is possible and what will work!

    Have FUN and experiment!
     
  5. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I've used these before (well, actually their predecessor, the B&W version that was popular in the 1960s -- same exact design, MFJ just copied what B&W did).

    Outdoors on a balcony will surely be better than indoors. How well it works depends a lot on how your route the "counterpoise" wire; actually, if you can clamp the antenna in place on a fairly permanent basis, instead of the counterpoise wire, you can attach a set of wire radials (use insulated wire the same color as your balcony railing or whatever so they blend in), the more, the merrier. I'd shoot for a dozen radials of various lengths, in as many directions as possible.

    You cannot use an antenna tuner to compensate for having the wrong coil tap -- that really doesn't work. The loading coil must be tapped in exactly the right spot for each frequency, and must be manually moved if you change bands, or change frequency within a band much (the 7.000 MHz tap won't work at 7.100, for example -- you really need to move the tap position slightly) and when doing this, leave the tuner OUT of the system altogether or it can be very confusing.

    But if you don't mind the exercise of moving the coil taps a lot, and can run some decent radial wires, indeed this can work about as well as a good mobile whip on a car or truck.
     
    K4MSM likes this.

Share This Page

ad: MesaHamfest-1