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Author Topic: 02 Grand Cherokee, antennas, mounts, relays...  (Read 613 times)
N0TZC
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« on: October 24, 2005, 10:06:54 AM »

Hello all, I got my ticket over 10 years ago but until recently never started to take things seriously.  A no-code tech, I'm now studying for  my 5wpm test and hoping that I can expand past my SW radio over time.  For now, I'd like to move past my old Alinco DJ-580, and get myself  something mobile for the around town communications during drive time.

Here's where I sit - I wanted a dual band radio that I would also equip as an alphanumeric scanner - I didnt' want to end up with 5 full size  radios strapped across the underside of my dash, but instead a simple  mount of a detachable face that could be easily read.  I think I've  found this in the Icom IC-208H, it can hold a lot of memories, and has  an alpha display so I can easily view who I'm listening too.  I've seen
some good reviews on eHam.net, so unless someone has other ideas, I  think thats where I'm headed.

Next - and what appears to be the bigger problem - the antenna.  At first I was thinking I'd just go glass mount, but since then I've read articles about their poor performance and concerns about their operation through modern car windows that are often tinted with metal.  I was unable to find any information on the 02 Cherokee to see if it had the bad kind of tint, but other postings I read about guys who notice no change in results after losing the glass-mount whip, and the
208h's 55w output (and my being unable to find a glass mount that could handle more than 50w) cause me to think that wasn't the best route.

From there I thought about Comet's EX104B, rated at 100w it was small and could do the job - then the mounting became the issue.  The 02 Cherokee is SEVERELY lacking in 'lip' locations to mount an antenna.  The rear door opens and its top side folds inward in a way making a lip mount impossible, and the body/roof side has no lip at all.  I thought about using the lip along the side edge of the rear door with a Comet CP-5m mount, but the way the rear window glass sits over it, there's really no way I can see to attach a mount to it.

So, I'm back to glass mount (and hoping the extra 5w doesnt kill it) ---- unless I want to go with a mount for a luggage rail, or drill holes.

No holes.

And I'm not wanting to the the luggage mount because I don't want 18 inches of exposed wire out side my car - which is why we're also not going mag mount.

I had thoguht of the 'window clip' that I saw at Universal Radio, as it seems like a good way to get an antenna into a location where you'd use a glass mount, but has an actual wire - however I havent been able to
find any opinions on it.  I also found what I thought was a Larsen mount that was adhesive, but haven't found much info on that either.

LASTLY - I found an AWEOMSE article here about mobile amatuer radio.  It was a guy's 30 years of experience, and it was VERY informative.  He like so many others suggested connecting directly to the battery - but I don't want my radio on if the car isn't on.   Someone in usenet suggested installing a 30 amp relay... but that's not really 'directly' to the battery - is it 'direct' enough?

So, I'm looking for suggestions on relays and mounts and antennas - heh, and if any of you have put a remote head radio in your 02 Grand Cherokee, send me a pic of where you mounted that head!  Any suggestions on any of this are appreciated, and info on posted pics of installs encouraged -thanks again.

Richard
N0TZC
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N3ZKP
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« Reply #1 on: October 24, 2005, 11:56:27 AM »

<< And I'm not wanting to the the luggage mount because I don't want 18 inches of exposed wire out side my car - which is why we're also not going mag mount. >>

Then you are going to have a problem, my friend.If you don't have an exposed antenna, you aren't going to talk very far. An inside antenna is going to put 55w of RF very close to you and your passengers and 2m/440 is one of the sets of frequencies that the body is very succeptable to.

Is there some particular reason you don't want an exposed antenna?

You can have "stealth" and you can have performance, but not generally at the same time.

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K5LXP
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« Reply #2 on: October 24, 2005, 11:57:47 AM »

Can't help you with antennas, you're on your own there.  You've placed conditions against using just about every kind of useful antenna there is.  A rubber duck under the seat does meet all of your criteria though...

As far as power, running it through a high current relay is fine, I do it on all my vehicles for the same reason.  You connect the battery source through appropriate fusing through the relay to the rig, then key the coil with a switched ignition source from the fuse block.  I take it a step further and build a time delay circuit out of a cap, resistor and transistor to provide about a 5 second delay from key on to relay on to give time for the engine to start and power to stabilize.  You can also buy these time delay on/off units commercially.

Mark K5LXP
Albuquerque, NM
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N0TZC
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« Reply #3 on: October 24, 2005, 12:09:33 PM »

I'm sorry, I wasn't very clear -- I don't mind having an antenna outside the car at all... if I could have my way there would be a lip mount that would be able to fit around the glass from the rear window.

What I meant was - if I put a mount on the luggage rack rails, then I'll have at least 18" of wire between that and the nearst opening into the car.  This issue I wouldn't have with a lip or glass mount.  A mag mount is a possibility, as it would have less wire outside, but still it would have some (and be much more targetable by vandles), plus, I'm not looking forward to having the big magnet base.

But YES I want the antenna outside - thats my dilema!

Thanks again, keep the comments & ideas coming!

Richard
N0TZC
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N0TZC
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« Reply #4 on: October 24, 2005, 12:11:28 PM »

<<You can also buy these time delay on/off units commercially. >>

Mark - I'm not that handy with things yet - what would a commercially available relay & delay be called?  Is there a name other than 'delayed relay'?  And where would you start looking for something like that?

Thanks,

Richard
N0TZC
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K5LXP
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« Reply #5 on: October 24, 2005, 01:30:09 PM »


> I'll have at least 18" of wire between that and
> the nearst opening into the car.
> I'm not looking forward to having the big magnet base.
> But YES I want the antenna outside

If you drilled a hole all of those problems go away.

I digress...


> what would a commercially available relay & delay be
> called?

The one I'm thinking of comes from here:

<http://www.acdcind.com>


Mark K5LXP
Albuquerque, NM
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K0BG
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« Reply #6 on: October 24, 2005, 04:15:10 PM »

Home brewing a relay is rather easy, even if you install the delay Mark talked about. Radio Shake sells all of the parts, and I'd guess it would cost all of $10 if that much.

The 208 draw 800 mils on standby, so if you left it on on over night, it would be no big deal. I thought the Icom has an auto-off, but apparently it doesn't.

You will not much sympathy about not drilling a hole. It is the only way to go. A NMO2/70 Larsen will fit you bill quite nicely.

ALan, KØBG
www.k0bg.com
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AA4PB
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« Reply #7 on: October 25, 2005, 08:56:08 AM »

On most modern vehicles you don't need the relay delay if you connect the coil across the accessory line. The ignition switch is designed so that the accessory line goes "dead" before the starter is engaged and doesn't return "live" until the key is back in the run position.
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K5LXP
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« Reply #8 on: October 25, 2005, 09:34:52 AM »

What the delay does for you is twofold.  One, it keeps the radio from being power cycled between on-start-on. Second, is the power from the alternator is just coming up for a second or so after the engine catches, and will do it's best to try and replenish the battery.  This is when the power is 'dirtiest'.

Mark K5LXP
Albuquerque, NM
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KB1LKR
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« Reply #9 on: October 25, 2005, 03:28:34 PM »

You could use the luggage rack mount and neatly (but not too tightly) tie-wrap the coax to the rack till you were close to the hatch, or you could lip mount the antenna on the rear hatch -- this may be the easest to implement, if not the least expensive.

Assuming you do not have a combination of luggage rack and power sun roof that prevent it you could drill (or have drilled by a radio shop) a hole and put a permanant mount on it. You might also look at opening the hood and screwing an L bracket to the front fender edge (just below the hood edge when closed), on the side opposite the AM/FM antenna, though this may require feeding the coax thru the firewall, and results in a lower antenna position than a hatch, loggage or roof hole mount. Whatever you do, use an NMO mount, vs a UHF.
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