Community Forums

coupevilleDF · 07-19-2014, 05:25 PM

I won a Yaesu FFT2900r mobile radio as a door prize on Field Day. We are new hams so this is our first radio beyond the handheld. It is 2 meter only with up to 75 watts of power. I would like mount it in the motor home (35' Georgetown) as a mobile/base. I do not really want it in the driver's area but will use it when parked, either in a campground or when dry camping.

I have a plan but would appreciate constructive criticism and comments to help me make it work or to kill it if it is not feasible.

Location: I am planning to station the radio on the table behind the passenger seat. This is a folding table so I will only use it there when parked. The radio weighs a ton, so I do not think the table would handle this weight while under way.

Power: The location stated above is just forward of the batteries. The pig tail that came with the radio should reach the batteries under the entry step. I will probably drill a hole in the floor right next to the door the bring the cables into the cabin. I plan to use the house batteries (the chassis battery is located there as well but I think the house batteries are a better source of power).

Antenna: This is where is gets complicated. I have looked at several options and this is the solution I like the best if you all think it will work. This approach is based on using the following antenna - ANLI WH-713 High Gain DualBand VHF/UHF Mobile Ham Radio Antenna - 2M/440. Two reasons for picking this antenna are 1) it should also work with the hand held radios which are Yaesu FT60 dual band, and 2) it will lay flat while traveling.

Install a mirror mount on the roof rack into which I can screw the selected antenna. The roof rack wold serve as the ground plane.
The selected mirror mount has a 17 foot lead which I would run down the ladder using zip ties.
Run a coax line (possibly RG-213) forward following the frame, possibly securing it to the bottom of the floor. Ideas for securing the line are welcome.
Route the cable up the same hole drilled earlier for the power line.
Waterproof the connectors.
Weather proof the entry into the cabin. I plan to create a custom wood trim piece that would hide the hole.

Does this all make sense? Will it work? Do I need to ground the antenna to the frame (it might be attached to the aluminum coach frame but I doubt it)? Am I likely to generate RF interference along the way?

Thanks all for your thoughts.

KG7JCA

SkipRD · 07-20-2014, 04:12 AM

I'm not familiar with the brand or model you cite, but a fold-over 2m antenna should work fine. A half-wave antenna is often used because it is less ground dependent. In that regard, I wouldn't count on the roof rack doing much as an RF ground. Some people say a 1/2-wave square metal surface is needed, I.e. a 3'x3' surface for 2 meters. But I've seen half-wave antennas used on RVs, boats, motorcycles, and HTs (collapsible variety) and they work quite well with essentially zippo RF ground. With a half-wave, I wouldn't worry about bonding the rack or getting stray RF. And I wouldn't do the ground-strap-to-the-frame thing. That puts the radiating portion of the antenna far away from what you think is its RF ground and makes the ground strap a radiating element.

You could get really snazzy and use a motorized fold-over.

As to location, I've used the FT-2900's little brothers for years, an FT-1900 now and an FT-1500 before that. They were all mounted hanging from plastic dashboards so I'm surprised there's a weight issue. And operating mobile is fun (mostly over repeaters because 146.52 is surprisingly dead). But do what is best.

"Location" otherwise and "power" both sound right.

Maybe others will chime in with more informed suggestions. Keep us posted.

73 Skip K4EAK

coupevilleDF · 07-21-2014, 03:40 PM

Thanks for your thoghts. I am headed to Oregon with the MH on Friday so I will stop at HRO in Portland to get supplies. I will post the final install based on any additional suggestions they might have.

YC1 · 07-21-2014, 03:47 PM

Sounds like you have it covered. Split wrap around the coax and nylon ties but do not over tighten the ties. You do not want to distort the coax. In some cases you can run a small flexible hose with the ends cut off or even small pvc to protect it. It is tuff enough normally to run along the frame by itself but you have to decide how much abuse it will get.