Anyone found a good 121.5 mobile antenna?

[JoeTomasone]

Now that my MK4 Sniffer is here, I've been finding out how craptastic the antenna I had been using for 121.5 in the car is (a Radio Shack mag-mount scanner antenna with MUCH better performance on 2m..).

Has anyone found a good antenna for 121.5 with good gain?  I'd like to find something with a decently narrow bandwidth.   The only one I have identified thus far is a Larsen http://www.wingsandwheels.com/page14.htm, but I've had bad luck quality-wise from them in the past and would prefer to avoid them unless nothing else can be found.

[sardak]

I used to have a 5/8 wave 2m, NMO mount antenna on the roof of a Suburban, hooked to an L-Per.  One night on what turned out to be a distress crash, I wasn't hearing the signal in places where I should have.

Afterwards, running some field tests with practice beacons and on non-distress signals, I found that a 1/4 wave antenna cut to 121.5 had much better performance than the 5/8 wave 2m.  The 5/8 wave worked as it should on 2m.  I've been using the 1/4 wave with the L-Per ever since.

It's a Larsen NMOQ88, available from HRO.  I've been using Larsen mobiles for almost 30 years and have no complaints about them.

Mike

[JoeTomasone]

Hrmh, can't seem to find that antenna in the HRO catalog... Nor in AES's.  How long ago did you get it?

And I definitely agree on the 1/4 wave 121.5 vs. 5/8 2m..   Even 1/4 wave 2m wouldn't work so well.

[SarDragon]

I bought a 1/2 wave 2m antenna at Fry's and put a new whip on it, cut to the correct length. I cut it long, hooked it up to an analyzer, and started snipping off 1/8" bits until it came into tune.

For the whip, the best stuff to get is stainless or chromed piano (music) wire, but regular stuff will work, too. I just cleaned off the surface corrosion, and covered it with heat shrink tubing. Works great.

[sardak]

Hrmh, can't seem to find that antenna in the HRO catalog... Nor in AES's.  How long ago did you get it?

HRO has it but doesn't list it in the catalog.  On HRO's homepage, put NMOQ88 in the "Model" search box.  There are both black and chrome versions and both are listed as being in stock.  The antenna doesn't show up on a search at AES.

I've known people who made whips out of stainless steel welding rod.

Mike

[Duke Dillio]

Now if I could only figure out how to make my own L-per out of parts from Radio Shack.....

[JoeTomasone]

Don't bother - look into the MK4 - seriously.

At any rate, I'm really hoping to find something commercial and easily available to recommend as a "ready to order" UDF kit to replace the L-Per - so making something, while fine for me, doesn't quite meet the need.

[Duke Dillio]

Don't bother - look into the MK4 - seriously.

At any rate, I'm really hoping to find something commercial and easily available to recommend as a "ready to order" UDF kit to replace the L-Per - so making something, while fine for me, doesn't quite meet the need.

Sure thing...  Quick question though...  What's an MK4?  Who makes it and what not?

[JoeTomasone]

Don't bother - look into the MK4 - seriously.

At any rate, I'm really hoping to find something commercial and easily available to recommend as a "ready to order" UDF kit to replace the L-Per - so making something, while fine for me, doesn't quite meet the need.

Sure thing...  Quick question though...  What's an MK4?  Who makes it and what not?

Look here.  http://captalk.net/index.php?topic=5048.0

[JoeTomasone]

OK, I've got a few on the way.   Ironically, one place I ordered one from was...... Ltronics.   

[JoeTomasone]

Since this post was just referenced in a new one, I thought it would be a good idea to update this.

The 121.5 mag mount antenna from L-Tronics (makers of the L-Per) beat out all of the other 121.5 antennas I tried, and it was the lowest priced ($25).

[Spaceman3750]

Can you use the 121.5 antenna for 121.775 as well? Also, do you just use that for DFing inside a vehicle or can you use it on foot as well?

I can DF but I don't understand the antenna stuff behind it.

[SarDragon]

Yeah, a 121.5 antenna works just fine for 121.775. Remember, you're not transmitting, so accurate length isn't as critical.

[JoeTomasone]

Also, do you just use that for DFing inside a vehicle or can you use it on foot as well?

That is a magnet-mount vehicle antenna, so it is used just inside the vehicle. 

For on-foot applications, it depends what you are using to DF.   If you're using the L-Per, use the antenna that came with it.   If it's something else, then you likely have some options, but the permutations are too numerous to list here.

[rroberts]

That is EXACTLY what I have been looking for.  I can't afford the ~$1000 to do the entire setup, but I can get just the Mag mounted antenna and connect it to an ICOM IC-7000 when on a UDF mission.  Once we start to get a decent signal, we can play with the ATT to try and zoom in to the general area, then we can DF it with our CAP gear.

[JoeTomasone]

That will get you started, but you need not spend $1000 for a "top of the line" setup.  Do a search for threads on the MK4 sniffer.