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Mobile unit temporary in car

Discussion in 'Mobile Radio' started by W9BXX, Jan 15, 2014.

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  1. AG6JU

    AG6JU Ham Member QRZ Page

  2. W1GUH

    W1GUH Ham Member QRZ Page

    I've used an FT-857 and an FT-817 a lot in the car. Both radios worked very, very well in that capacity.

    With the '857 I used a suction cup windshield mount for the control head. (Be careful with this one, I understand that those mounts are illegal in some states.) That puts the frequency readout where it's easily seen and you don't have to look down very far to see it, like if it's mounted on the console. And, with a remote-control mic, one never has to "reach up" to the control head. All the controls that are on the head are in the palm of your hand, at least after one has practiced with it. And that's very easy and quick to take down and stow out of site.

    If your console has one of those cubby-holes that's there for sound system improvement, sometimes that can be taken out and turned around so the back wall of the cubby-hole is approx. flush with the dashboard. Then, you can drill holes in that to use the manufacturer's control head bracket.

    That radio does require special power wiring, and that proved to be a hassle because the car didn't have any convenient holes in the firewall to accommodate that. For I while I ran the wire out of the back end of the hood and into the car window. That worked fine and didn't attract the hairy eyeball from the authorities. But there's a trivial solution. Somebody pointed out to me (not a ham, but a guy who installs car stereos) that I could shove that wire down in the joint between the windshield pillar and the front fender. Viola! Invisible installation!

    I would think that an 11A load through a cigarette lighter would cause enough of a voltage drop to be a problem, even tho' the lighter is fused at 15A.

    And the '857 itself - it usually wound up under the passenger seat with whatever make-shift stuff I had around to keep it there. (And, of course, the "turns into a projectile" is, in the end, a valid thing to say. OTOH, that is easily gotten around by driving so it doesn't turn into a projectile...really). Cooling that radio was never a problem, anywhere. Maybe if I was operating RTTY in the mobile or I was sitting in a closed car on a very hot day I could have run into problems, but for normal SSB operating, forget about it. Not a problem. Besides, that radio's cooling is in a big external heat sink on the back of the radio - how ya gonna block that? I don't know about other equivalent radios, but that '857 has been the most un-fussy radio I think I've used. Voltage drops because of changing current don't affect it as long as it never goes below the spec. Temp. doesn't bother it either. It just works...and works....and works....and works.

    The '817 was much simpler, of course. It's tiny and sits in the console as nice as anything, and is easily powered by the cigarette lighter. Gets out very well, too.

    In any mobile installation I've used I've plugged the radio into the AUX input of the car's sound system. That costs absolutely nothing (who doesn't have a 1/8' phone plulg jumper already?) and will provide all the good quality sound you could want. And a lot of current or recent car radios have EQ's built into them if you really want it to soulnd like a "communications" speaker. In any event it's free and easy to try. I've done this with both SS and Hollow state mobile radios with the same great results. Makes a TR-7 with the "no-filter" mod sound just like one of those great old console radios in the big wooden cabinets. Pity there's very little to listen to these days!
  3. K3LFC

    K3LFC Ham Member QRZ Page

    Hey, use can buy 12 volt 20a batteries online for 35$ , they weigh about 4lbs. and use a mag mount antenna. batteries inc. on internet!!

    k3lfc 73s
  4. N4OAH

    N4OAH Ham Member QRZ Page

    It is possible to move your radio between house and car with minimal difficulty, but it takes some planning. When you are dealing with a mobile rig, rule no. 1 is always wire directly from the battery to your rig, anything else is asking for trouble. You could run an HT off of a cig lighter, but it is not recommended with anything bigger. As to your antenna, I would say just use the mag mount, as a antenna inside the car doesn't work too well. If the repeater dose well in the area, then a HT will do ok inside the car, but you won't get much better than that without going outside the car.

    If it were me, I would run the + and - directly from the battery, and just move the wires out of the way when not in use. I would be tempted to just stay with a small 1/4 wave mag mount, maybe stick it on so it looks like an FM antenna. 73 and good luck with it,
  5. KC3CIB

    KC3CIB Ham Member QRZ Page

    This is what i use. a portable box with an Powerwerks power supply and a TM-V71A. Have a power cord direct to battery for mobile use. Works good if you have the physical room for laying the box. Will eventually remote mount the faceplate with an extension cable for extended use in vehicle. I primarily use as a fixed station. The box is open front and back allowing sufficient air for cooling. BTW I made the box myself.
  6. K0RGR

    K0RGR Premium Subscriber QRZ Page

    Before you wire directly to the battery, make sure that is how the car manufacturer recommends. These days, they typically provide a separate attachment point for grounding - connecting directly to the battery will potentially screw up the charging system for the car, because there are sensors attached there, too. K0BG's web site has much more on this.

    Personally, I would run a line to the battery or the 'designated grounding spot'. In addition, I like to follow Motorola's idea of grounding the radio to the car body at the radio - it can greatly reduce the voltage drop in the leads and eliminate other 'ground loop' issues.

    I'd find a place where the FT7900 main body fits easily with reasonable airflow around it. My TMD710 is mounted in a pocket behind the back seats in my pickup - it fits perfectly there, and the heatsinks are in the clear. Most of the time, I mount the radio bodies under the front seat. If you can find a location where the radio can't 'fly' forward, I think that's good enough. Otherwise, do secure it, either with their mount or something else that will hold it securely in place. This can make it difficult to move a radio from the car to the house, an operation I think is a pain in the neck, but I am older and have little patience for such.

    If you have enough cup holders, a cup holder mount to support the control head would look and work great. My pickup has 6 cup holders, so one is not missed. I've also used the 'goose neck' mounts that bolt under a seat mounting screw - those work pretty well, but don't move them around excessively. The 'stalk' is a solid piece of metal that you will eventually break from moving it too many times.

    I like lip mounts for antennas over mag mounts. Unless you have a reason for 'stealth', I'd use a lip mount, if possible.
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