HAM Antenna related

[Idahostat]

Hello Group

My used Hallmark has Yakima tracks added to the roof. I did not see any posts on searching for radio other than a short CB question and the couple of HAM operators who responded plus a CB user.

As I do not have a metal roof for a ground plane, direction to other web sites for adaptations ( I have used a cookie sheet with a mag mount in the past which was fine after a fashion for 2 meter ).

EHAM is searchable but I have not had a good response for camper related and was wondering if anyone here as the experience or knows of good thread on another site.

I did check out the "comm" thread on the "Other off road site" and found a reference for someone who's ICON looked familiar from this site, he acknowledged using a hood mount antenna for I assume 2 meter radio. I was thinking of using the Hallmark for my radio shack and wanted to best implement the roof mounting options I have ( eventually expanding into HF/NVIS, 2 meter ). Sheet metal between the Yakima tracks or a metal tray/platform like the Rhino steel mesh flat units that are available ( looking at a 59" x 26" unit ) and it would be raised of the tracks several inches so ground might be interesting.

Terence

 

[PaulT]

For 2m look at 1/2 wave antennas. They do not require a ground plane. Metz makes one that is used on boats like their marine VHF antennas. For mobile HF, K6ON is likely the expert here. For stationary use, I made a mount that attches to my jack mounts as I don't leave my jacks on the camper.

It is simple to make. Just went to my favorite Ace HW store, bought a 48" long 2" angle aluminum 1/8" thickness. Held the angle on the jack mounr where I wanted it & used a sping loaded center punch to mark the locations for three holes. Drilled the holes. & checked that I did it correctly.

While at Ace, I bought three SS bolts, flat & split washers, and some plastic handled wing nuts. Installed the bolts and cheked for strength, all seemed well, so I then drilled holes for some Quick Fist rubber pipe clamps bought at the local Sportsman's Warehouse & mounted those. http://www.quickfist.com/index.php/quick-fist-mounts.html

Took my 16 ft telescoping aluminum flagpole from Harbor Freight and clamped it into the Quick Fists. It seemed stable, so I mounted an Arrow dual band aluminum J-Pole with coax to the flagpole and remounted the flagpole into the Quick Fists. Used that as my antenna for the 2017 Hood to Coast relay. It worked great for the 24 hour duration at my location to provide emergency communications for the event.

I will order one of the HyEndFed antennas like K6ON recommends and hang it in lieu of or just below the J-Pole for NVIS use.

Paul

 

[ntsqd]

I only do 2M for comms on trips. I used a Larsen NGP NMO base antenna on a mast that I made that also bolts to the jack bracket. The pic is huge so details can be zoomed into if desired. Note that in spite of the deflector 'cage' around the base that I didn't build it tall enough and tree limbs have bent the whip.

I have debated the merit and effectiveness of laminating some aluminum foil to non-metallic surfaces to create a ground plane, but my knowledge of RF is pretty limited.

I also built a J-Pole from 3/4" copper tube which is hoisted up on a 25' tall mast when we are doing base station - relay work for the races. For strength in transport I connected the upper end of the short leg to the main leg with PVC pipe pieces and employed a copper pipe union just above that connection to enable shortening the overall length for transport.

 

[Idahostat]

Thanks for both of the responses. I will examine my jack mounts and look into the fabrication. Did ether of you bring coax into the camper and if so how? I have examined my available utility doors ( access to the hot water heater, the outside shower, water fill point, all have doors and have thought about barrel connector on the interior of one or the other of my three hinged door choices ), so rather than drill another hole in my side walls.

Or did you both settle for just feeding the coax into the cab?

Again thanks for the responses.

Terence

 

[PaulT]

Usually, I operate outside from a table under the awning or a 10x10 canopy. If it is raining enough to be inside the camper, the coax goes through a turnbuckle door or through the camper door if the rear awning is on the camper.

Sometimes, setting up a radio for crossband operation to allow me to walk around the area works best. Underway, I just use the NMO mounted dualband antenna on the truck cab.

Paul

 

[Wallowa]

How are you folks getting the coax into the cab of the truck?

Phil

 

[craig333]

I ran mine under the rubber door seal.

 

[Wallowa]

Yes same as I am doing..HAM stuff all new to me..

Phil

 

[huskyrunnr]

Are you squared away on a 2m antenna? Rather than a j pole, I lean toward PaulT's suggestion of something like the Metz antenna which is likely a tapped resonator feeding a half wave dipole. J poles are great as long as the matching section does not couple to anything nearby. The j pole matching section is a two wire transmission line and the electromagnetic field fills the surroundings which can be a problem. Do you have an antenna analyzer? If so, I can point you to published plans for the old aea hot rod antenna with a variable capacitor for a perfect swr.

 

[ntsqd]

I use Ancor Marine RG-58 coax because of it's stranded center conductor. Single strand center conductor coax just doesn't seem to last very long in a vehicle before giving me trouble.

I don't bring the coax into the camper. I brought it into the truck via an OEM rubber grommet in the firewall. I used to bring it in thru a simple compression style window seal (not thru a typical window seal like in a cab door), but even that finally collapsed the coax's internal insulation to the point where I need to send out the radio as I suspect it is damaged.

The J-Pole has worked fine for the intended use, which is rare these days. Note that the use is racing comms, not RACES. SWR was set perfect for the freq's used. I found an online build & tuning guide and my only three deviations from that standard build were 3/4" instead of 1/2" copper pipe, the PVC 'bridge' tying the top of the short leg to the main section for strength in transport, and the union to allow shortening it for transport.

 

[huskyrunnr]

Ah, I see that Larsen is the 144 MHz version of the Metz. Looked it up and saw NGP stands for No Ground Plane. I'm not familiar with commercial offerings. That looks like a good one. How does the SWR look?

MFJ makes a version of the old AEA Hotrod. Its called the Long Ranger. I bought several for my students to mess around with. All of them were horribly out of tune and match. I know Larsen has a good rep.

 

[ntsqd]

When trimmed according to their chart the SWR was spot-on.

 

[Idahostat]

Hello Group

When I put antenna(s) on the roof ( it is an option ) rather than running a bracket extension off of the camper jack mount which is doable I am considering torque a possible problem ( I think if I just use foldable bases for the antennas for the camper/radios which would only be deployed/erected when "camped", "my" torque paranoia will be less ).

Any way whether I use a bracket extension or my camper roof I will need to ground, right? If so braided not single wire grounding straps to the frame, I am intimidated by the a braided strap running to the roof ( it does have to flex or fold, unfold ( "pop-Up thing" ) any thoughts on this, problems experienced or foreseen?

Terence

 

[ntsqd]

I pondered putting the antenna on the camper roof. That metal roof sure looks like a nice ground plane even if it is aluminum.

The reason that I didn't pursue it is because every time the roof went up or down it would exercise the coax. I could see the center conductor in that section fatiguing pretty fast - even though I tend to use Ancor Marine coax on vehicles for its stranded center conductor. So then bulkhead connectors top and bottom to make replacing that section of coax fast & simple? Could do it, didn't like it.

 

[Idahostat]

Thanks NTSQD

Yeah the flexing of the coax and grounding flex for the roof seems difficult.

I have decided for the time being to stick with a hood mounting ( Comet 720 for the 27meter Untunable/factory tuned "Francis" ), NMO Larsen for the 2/70 ), listening mostly on the 27 meter ( leave off most of time ) Yaesu will keep me reading and fiddling for the rest of my days I care to spend on it.

When I get better acquainted with the new Yaesu 2/70 in the cab I will do a separate pair of antennas ( structure mounted off the camper jack or just my buddy pole on a tripod ) for the HF/VHF I plan to put in the camper and expect to use wile parked/camping.

Terence

 

[Trout1 Project]

Took the kids for a late season fishing trip to the Deschutes then came home and had a great couple evenings in the workshop on my radio install. Put a TYT TH7800 Dual Band with a TRAM NMO antenna on the roof rack. First experience using CHIRP and it was effortless downloads.