Antenna Specialists MON-R51

[cbehr91]

I picked up this antenna on eBay. It was "new" old stock and was shipped to me in its original box which was pretty cool. The instructions for mounting that came with the antenna (copyright 1996 BTW) had something that caught my eye in that it says to only use the antenna on a trunk lid or rear deck and makes no mention to using the center of the roof for mounting.

I think I can see why these antennas pick up so well. One being the coax is only 12' in length so there's not going to be much loss, if any, and the antenna and mount are extremely well constructed. The only (minor) downside is I will have to pick up a MOT-BNC adapter.

 

[N9JIG]

The MON-51 is an awesome mobile antenna. I use them on NMO mounts occasionally when lo-band VHF is hopping.

Trunk lips work well for them since they are pretty tall. Putting them on the roof invites branch banging.

 

[cbehr91]

Yeah, it seems like a great antenna. It's a tad shorter than a VHF gain antenna. I did notice however you need a rather large NMO mount to make good contact. The round Larsen BNC mag mount doesn't have enough threads.

Sent from my SM-S765C using Tapatalk

 

[N9JIG]

These came with an adapter for the SO239 mount, I suspect these might have been better at physical contact than the NMO. I never used the included mounts, I had NMO's on my vehicles for decades. Once in a while I would have to bend down the little metal tab to get good contact.

The inch-tall plastic base that fits the NMO is the same straight-thru unit used on the A-S UHF gain antennas. I think the base for the VHF gain antennas was different (with a coil?) but that is taxing my memories from close to 30 years ago.

I often looked for alternative bases at hamfests and usually ended up buying a few original style ones out of junk boxes. Often I would find an A-S UHF antenna for a buck or 2 and buy it for the base and trash the whip.

I still have a half dozen MON-51 whips and a couple of the similar MON-52's (these had the 800 MHz. element below the coil). I used a couple in the attic on NMO ground planes, and hope to do the same this winter when the weather cools enough to spend some quality time in the attic.

I might put one on the roof of the car to replace the Comet antenna I have there now for a while to see how well they work. I can usually hear some occasional CHP low band here with the smaller one, maybe the MON-51 will increase that.

 

[mancow]

Is there anything like a coil in the bottom? I ask because I have a whip from one but no bottom part. I mounted it in a non coil NMO base but I'm not sure if it needs something else at the bottom.

 

[prcguy]

The stock base seems to be straight through but they put the equivalent of a chrome plated fender washer between the whip and base which would affect the match.
prcguy

Is there anything like a coil in the bottom? I ask because I have a whip from one but no bottom part. I mounted it in a non coil NMO base but I'm not sure if it needs something else at the bottom.

 

[N9JIG]

Over the years most of those washers from my antennas had been lost and I never noticed any performance differences. I did put a dab of Krazy Glue on one and that kept it there for a few years...

 

[_Wilson_]

Is there anything like a coil in the bottom? I ask because I have a whip from one but no bottom part. I mounted it in a non coil NMO base but I'm not sure if it needs something else at the bottom.

Yes! I have a few deferent coil models i have collected over the yeArs and each one has a copper load the pictures are in my albume.

 

[cbehr91]

I adjusted the center pin a little bit and now it makes great contact with my round Larsen mag mount, so it can be done to fit other name brand NMO mounts.

Also, it looks like you can still buy Antenna Specialists coils from Antenna Farm.

 

[cbehr91]

Is there anything like a coil in the bottom? I ask because I have a whip from one but no bottom part. I mounted it in a non coil NMO base but I'm not sure if it needs something else at the bottom.

The installation sheet for the MON antenna says the coil is part no. K722.

http://www.theantennafarm.com/catalog/pctel-k722-4299.html

 

[_Wilson_]

That's correct, A/S made several models two of which you can still get at the antenna farm. Com under antenna coil the k-722 and the k-725. From what I've learned A/S made about five deferent models k-222 and 2 more i have that have no part #, over all five that i have the k-722 seems to work the best, hope this helps.

 

[mancow]

Great. Thanks!

 

[_Wilson_]

Your most welcome, you'll enjoy the antenna when you get the base coil, one bit of advise, the base coils do not like sun light, my 1st one faded to almost a grey color and begain to get cracks, a few coats of plasti dip will protect it very well, and those coils can get filled with rain water over time and can freeze and crack the housing, i drilled a very small hol bout the size of a ball point pen, in the bottom side of the base coil in the white part, right next the contact tang, but be carefull when doing this that base plate is about the thickness of a 25 scent quarter.

 

[N9JIG]

Do any of you MON51 fans out there have a couple of the NMO-SO239 adapters that came with these? I need a couple and seem to have lost the ones from all of my MON-51's.

PM or email me if you do...

 

[_Wilson_]

PM sent.

 

[kh11]

MON-R51 instruction sheet

Guys, I was digging through an old box of parts and found a tattered copy of the instruction sheet. I would swear someone either on this forum or elsewhere was looking for it (for the cutting chart, I assume). I've scanned it and created a PDF. Is there someplace I can upload here it so it isn't lost for the ages?

 

[N9JIG]

Guys, I was digging through an old box of parts and found a tattered copy of the instruction sheet. I would swear someone either on this forum or elsewhere was looking for it (for the cutting chart, I assume). I've scanned it and created a PDF. Is there someplace I can upload here it so it isn't lost for the ages?

If you switch to full reply there is an Attachment icon, looks like a paper clip.

 

[kh11]

Hmm - didn't think of that (smacks head). Looks like I'm going to have to mess with the file, as it's larger than the board will allow for uploads.

 

[mancow]

Guys, I was digging through an old box of parts and found a tattered copy of the instruction sheet. I would swear someone either on this forum or elsewhere was looking for it (for the cutting chart, I assume). I've scanned it and created a PDF. Is there someplace I can upload here it so it isn't lost for the ages?

That was me. I would like to see it. Thanks.

 

[kh11]

That was me. I would like to see it. Thanks.

PM sent- I'll email a copy to you.