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Posted: 1/9/2013 8:34:49 PM EDT
[Last Edit: 1/9/2013 8:48:22 PM EDT by DocSarvis]
Recently upgraded to General and picked up an Icom 735 to get rolling w/o dropping a lot of coin out of the gate. Included in the sale was an older MFJ versa tuner II, 941-D. I'm not in a very good position to string up a big antenna as my lot is small and the power runs across the back of the yard, although there are some tall pines on the side of the house where the shack is located so there might be some options there. I was given an MFJ G5RV Jr and while I can't string it up outside properly I thought of maybe hanging it in the attic, kind of a Z shape should make it fit. We might be moving this year so I want to keep this simple antenna wise. I already have a home made 2M antenna up in the attic and have been chatting on the local repeaters before getting the ticket upgrade. Anyway here are two quick questions:

1. Should I mess with the tuner or just keep it simple with just the radio? The instructions kind of make sense.
2. Should I pick up another antenna? I can conceivably run coax from the radio into the attic and then a wire out the eve and up into a pine nearby. The problem I'm finding with the G5RV is I cannot get it set up in a proper "T" configuration, the ladder line will have to be routed around and through an eve vent if placed outside and would be mostly horizontal or laying on the insulation in the attic.

Thanks for the input, I'll probably look into one of the local clubs too for guidance....
Link Posted: 1/10/2013 2:24:18 AM EDT

Originally Posted By DocSarvis:


1. Should I mess with the tuner or just keep it simple with just the radio? The instructions kind of make sense. You can run it without a tuner if you prefer, just be prepared to buy a new radio every other week.
2. Should I pick up another antenna? I can conceivably run coax from the radio into the attic and then a wire out the eve and up into a pine nearby. The problem I'm finding with the G5RV is I cannot get it set up in a proper "T" configuration, the ladder line will have to be routed around and through an eve vent if placed outside and would be mostly horizontal or laying on the insulation in the attic I'd suggest a different antenna. There seem to be a lot of requirements for the G5RV, most of which cannot be met when installed in an attic. I run a Radiowavz DX40 Windom in the attic and have had great results. It's not in any kind of efficient configuration, either (i.e. the legs are installed to fit in the attic as close to an inverted Vee as possible).


Link Posted: 1/10/2013 12:09:53 PM EDT
How much room do you have in the attic to run a straight dipole? If it were me, I would do a coax fed dipole even if you have to bend it a little. Good choice on the IC 735. I have had four of them over the years and they are pretty much bullet-proof.
Link Posted: 1/10/2013 12:43:01 PM EDT
[Last Edit: 1/10/2013 12:47:34 PM EDT by DocSarvis]
I used eham and other reviews to look into the various used units I was seeing here and there and the 735 looked right up my alley, plus I remember my grandfather had all Icom gear so that was in the front of my mind too.

Up in my attic i would have about a 40' straight shot. I can't stand up in the attic so an inverted V setup can't be much longer than that. There are also two trees I could conceivably use on the side of my house to string up a wire between, it was just the setup needs of the G5RV Jr was not going to work very well once I really looked at what I was working with, The OCF wire mentioned above might be an option for outside. The gap into my attic above my shack is about 17' from one of the trees and about 40' from another that I could use without getting near any power lines, however there is nothing straight overhead to support the center of a dipole unless i hang the center right from the peak of the house and run wires down to the ground on each side.
Link Posted: 1/10/2013 4:53:49 PM EDT
A simple 1/2 wave dipole for 20m will only be 16 1/2 feet per side. Wind a simple coax choke balun at the feedpoint. This antenna will most likely will "tune" on 15 meters, but maybe not 10 meters. The choke balun is made from 8 ft. of the coax feedline coiled up at the feedpoint. The ARRL book says to make 6 or 7 turns from the 8 ft of coax.
Obligatory MS Paint of house/lot layout would be most helpful.
Link Posted: 1/10/2013 5:09:12 PM EDT
I would try as many different antennas as you can. Wire is relatively cheap. Buy an antenna handbook and start experimenting. I have a small wooded area behind my house so I have a bit more room than most people in a neighborhood. But I have settled on a few antennas as of late. I have a 160m windom, an inverted L for the lowbands and have had loops up and down for the past year. My goal is to be on the DXCC honor roll with wire antennas. Don't be discouraged with your small lot size you can do a lot with a little space. I am also playing with my first vertical. But I am not completely sure that it is the best solution for my needs. Experimenting with antennas is a lot of the fun with the hobby for me

Just because you can't put up a huge tower doesn't mean you can't work a lot of DX. Trust me.
Link Posted: 1/10/2013 7:26:06 PM EDT
[Last Edit: 1/10/2013 7:51:05 PM EDT by DocSarvis]
I think for some reason I'm putting too much thought into HF. I built my 2M antenna, hung it in the attic, and get great results just using it with an HT. I'm leaning towards just building 1/2 or 1/4 wave dipoles that will fit up in the attic or between my two trees and focus on a band or two to get rolling. Should I pick up a balun (or wind the cable at the feed point) at all or just go with a simple center insulator with a PL259 connector? There is a really nice ham store here in town so I can easily pick up whatever I need from them.
Link Posted: 1/11/2013 4:53:42 AM EDT
You can start with an "ugly" balun and decide later if you need more. If you do OCF dipoles common mode current can be an issue even with a ugly balun. Experiment, test, enjoy.
Link Posted: 1/11/2013 5:22:21 AM EDT
You want a 1/2 wave dipole.
Link Posted: 1/11/2013 5:48:10 AM EDT
Originally Posted By KB7DX:
You want a 1/2 wave dipole.


Yea that should work. Dipoles are gateway drugs.
Link Posted: 2/14/2013 12:46:00 PM EDT
Ok I've been playing around in the attic and outside a bit. I picked up a few of these and some wire as this place is here in town (very handy!)

http://www.universal-radio.com/catalog/antsup/5524.html

I was able to hear stations but my SWR was really high, even found the matching tuner for the 735 (AT-150) and it's not able to tune the wire. I started messing with getting a wire up into the trees outside but with the weather it's been kind of sketchy so I've just been playing on 2M lately with the jpole on the roof. After reading back through this thread I realized I did not put any kind of choke on the 20M dipole in the attic....is this the reason for the high SWR and being unable to tune it? My attic has an aluminum peak vent running the length of the roof and that along with the aluminum gutters is what I thought was causing the problem.

I've been studying the smaller HF verticals as a tower will never happen at this place and the Gap Titan DX has sparked my interest but that will have to wait until funds permit and I've already been on the air making contacts with some basic wires...
Link Posted: 2/14/2013 8:23:00 PM EDT
[Last Edit: 2/14/2013 8:24:53 PM EDT by KB7DX]
Most likely the dipole "legs" (wires) will need to be trimmed to get a good SWR. Measure the SWR on the upper end of the band (14.350) and then at the low end (14.000). If the SWR is better at the low end of the band, the legs will need to be shortened. Conversly, if the SWR is lower on the upper part of the band, the legs will need lengthened. That tuner, while a nice one, will only compensate for slight mis-matches and wasn't intended to tune an antenna that is way out of band.
The coax "balun" at the feedpoint is there to keep RF from coming back down the feedline and into the shack, not for SWR purposes.
For verticals, check out the Hustler BTV series. I have a 5BTV at my BOL and with just 4 ground radials it works well.

Oh, I used to frequent Universal back when I lived in the Buckeye State. Are the cats still there?
ETA -- How far from the roof peak/gutters are the wires?
Link Posted: 2/15/2013 7:10:57 AM EDT
[Last Edit: 2/15/2013 7:18:41 AM EDT by DocSarvis]
yep still all kinds of cats running around the shop....

I'm using the 735 to measure the SWR currently. I'll try what you suggested.

I looked at the hustler's as well and am thinking more of a roof top or mast mounted ant as my back yard isn't very large and full of pine tree roots so burying radials to keep them away from the dogs would be difficult.

the roof vent is right over head, maybe a few feet from the wire. the gutters are on either side, maybe 15 feet away. the attic space is not very tall.
Link Posted: 2/15/2013 12:08:40 PM EDT

Originally Posted By DocSarvis:
yep still all kinds of cats running around the shop....

I'm using the 735 to measure the SWR currently. I'll try what you suggested.

I looked at the hustler's as well and am thinking more of a roof top or mast mounted ant as my back yard isn't very large and full of pine tree roots so burying radials to keep them away from the dogs would be difficult.

the roof vent is right over head, maybe a few feet from the wire. the gutters are on either side, maybe 15 feet away. the attic space is not very tall.

Look into a 'skywire' loop antenna.

Link Posted: 2/15/2013 2:04:10 PM EDT
a smaller skywire would be the only option for me. main power/phone/cable lines run along the back side of my city lot and the feeder to the house cuts my back yard almost in half. the areas i'm looking at putting up a dipole or random wire outside are on the side and front of my lot to stay clear of the power lines.
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