• To anyone looking to acquire commercial radio programming software:

    Please do not make requests for copies of radio programming software which is sold (or was sold) by the manufacturer for any monetary value. All requests will be deleted and a forum infraction issued. Making a request such as this is attempting to engage in software piracy and this forum cannot be involved or associated with this activity. The same goes for any private transaction via Private Message. Even if you attempt to engage in this activity in PM's we will still enforce the forum rules. Your PM's are not private and the administration has the right to read them if there's a hint to criminal activity.

    If you are having trouble legally obtaining software please state so. We do not want any hurt feelings when your vague post is mistaken for a free request. It is YOUR responsibility to properly word your request.

    To obtain Motorola software see the Sticky in the Motorola forum.

    The various other vendors often permit their dealers to sell the software online (i.e., Kenwood). Please use Google or some other search engine to find a dealer that sells the software. Typically each series or individual radio requires its own software package. Often the Kenwood software is less than $100 so don't be a cheapskate; just purchase it.

    For M/A Com/Harris/GE, etc: there are two software packages that program all current and past radios. One package is for conventional programming and the other for trunked programming. The trunked package is in upwards of $2,500. The conventional package is more reasonable though is still several hundred dollars. The benefit is you do not need multiple versions for each radio (unlike Motorola).

    This is a large and very visible forum. We cannot jeopardize the ability to provide the RadioReference services by allowing this activity to occur. Please respect this.

NMO vs SO239

Status
Not open for further replies.

990adv

Member
Joined
Jan 7, 2010
Messages
138
Location
Central IL
I have decided to move a couple(maybe only one) of my mobile antennas to the roof of my 2004 Chevy Silverado. Currently the antennas I am moving are on L brackets using SO239 connectors. No problems at all.

I now have a few questions, the main one being is there something about an NMO mount that is that much better than using an SO239? I will be using backing metal on the inside no matter which mount type I use. Is the NMO more waterproof?

The antennas I plan to move are the VHF/UHF for my Icom 2820 and 220 for the Jetstream radio. Although, I have thought about just putting the VHF/UHF up there and installing a BackRack on the truck then mounting a couple of my other antennas on the BackRack.
 
Last edited:

KD0IPM

Member
Joined
May 2, 2011
Messages
49
I've done only a little bit of research, and have found that NMO is better. It is far more waterproof when the antenna is off, since the UHF/SO239 mount isn't waterproof at all without an antenna on. An NMO mount is fully waterproof without an antenna on. I'd recommend getting the Larsen mounts from theantennafarm.com
 

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
14,635
Location
SNCZCA01DS0
Larsen/Radiall sells both. NMO or PO, PO mount is the UHF type.

NMO's are far more popular for a vehicle antenna mount. While you can find PO type bases, you will have an easier time getting NMO mounts.

NMO mounts are lower profile, if you ever remove the antennas.
NMO mounts are physically bigger, likely spreading stress out over a bigger area.

I've installed probably 40 NMO mounts over the years, and never had one leak. I've never used backing plates on a metal vehicle roof, but have one non-metal roof tops. While nothing wrong with adding your own, if done right, you shouldn't need a backing plate on an NMO mount on your truck roof.

I've installed many of those 40 NMO's on the roof tops of Silverados, never an issue.

I'd suggest sticking with the more common NMO mounts rather than the PO/UHF mounts. If you are really stuck on the PO/UHF mounts, you can purchase adapters that will screw onto an NMO mount and give you a UHF connector.
 

LtDoc

Member
Joined
Dec 4, 2006
Messages
2,145
Location
Oklahoma
One plus for the NMO mount (as far as I'm concerned) is that it doesn't require as much room under the roof like most 'PO' type mounts do. The NMO is almost a 'standard' for VHF/UHF mounts, there's a jillian of them around.
- 'Doc
 

fineshot1

Member
Joined
Sep 17, 2004
Messages
2,507
Location
NJ USA (Republic of NJ)
another plus for nmo mounts is its easier to find adapters from nmo to other type mounts.

nmo to uhf or 3/8 thread adapters are common. i have also found nmo to N adapters.

try finding an adapter going in the opposite direction, not gonna happen. so IMO
nmo mounts give the user a lot for flexibility in antenna choices.
 

jhooten

Member
Joined
Mar 6, 2004
Messages
1,503
Location
Paige, Republic of Texas
another plus for nmo mounts is its easier to find adapters from nmo to other type mounts.

nmo to uhf or 3/8 thread adapters are common. i have also found nmo to N adapters.

try finding an adapter going in the opposite direction, not gonna happen. so IMO
nmo mounts give the user a lot for flexibility in antenna choices.
National Communications Group part number AD-25M.
 

SCPD

QRT
Joined
Feb 24, 2001
Messages
0
Location
Virginia
My personal experience has been that SO-239 mounts make better contact with the antenna, unless the antenna has a spring loaded contact. I have also had a Larsen antenna seize to the NMO mount, I guess due to the antenna part being stainless and the mount being brass. A couple of weeks ago our ARES group was working a bicycle race from the County EMA's mobile command bus. We were using a local 2 meter repeater and everything seemed to be working ok. After the event I tried some 440 machines and couldn't bring any of them up. Turns out the antenna wasn't making contact with the NMO mount. After rebending the metal tab we got it working again.
 
Last edited:

fineshot1

Member
Joined
Sep 17, 2004
Messages
2,507
Location
NJ USA (Republic of NJ)

jhooten

Member
Joined
Mar 6, 2004
Messages
1,503
Location
Paige, Republic of Texas
The guy who told me about them is an old field comm guy. He said what he does when he needs to go through a 4X4 square tube on top of the rig to mount the antenna as high up as he can is to take one of these kits and a 6" long through the wall extended coupler, drill through the tube, put the coupler through and secure it with the big nuts, add the kit to the top, screw on a 1/4 wave spike, run RG-213 down to the tool house, and talk from horizon to horizon on a 50 watt radio.
 

jeatock

Member
Feed Provider
Joined
Jul 9, 2003
Messages
611
Location
090-45-50 W, 39-43-22 N
Go NMO

I buy them by the gross, 2 or 3 times a year. There are brass and stainless, 1GHz and 6GHZ models available, and every flavor of coax known to man- coax choice is more critical than anything else. Don't buy the pre-installed coax connector.

Don't pull the headliner down. Pull (hard) on the upper door seal, and peek under the headliner to find a spot where you don't drill through a stiffener or roof brace. The door seal will go back and reseal fine. Don't pull more than you need for easy access.

Tape measure the center of the roof. Use the inside of the door frames as reference on both sides- car builders don't always get their roof seams straight. Measure and check twice, drill once. Re-check for stiffeners and braces. X marks the spot.

If you are installing on a newer pickup, pull the third brake light out of the back and drill the holl as far forward as you can. 4" from the back tunes fine on VHF, and higher freq's won't care.

Drill an exactly 3/4" hole from the outside, but don't go too deep and into the headliner. If you borrow an electrician's s hole saw, make sure that it will drill a 0.750" hole, and not a conduit-size hole. If you don't have a $150 carbide antenna install hole saw, wrap the outside of a home store hole saw with tape and keep the pilot short to save the headliner. Don't panic if the hole saw wanders just a bit. It's only paint, and the mount will hide it. Watch out for the piece, it's HOT, but not hot enough to damage the headliner. Pull it out lest it rattle for the next ten years.

Get a 3' piece of 1/4" nylon tube (ice-maker water supply tube works great). Put the tube in the hole and work it straight sideways to the door. Have a flashlight handy, and a coat-hanger to reach the nylon tube when it bends the wrong way. Don't panic if you bend the edge of the headliner a bit- they're self healing.

Plain old electric tape will work nicely when you slice a finger open and are bleeding all over the car.

From the hole, slide the coax into the tube an inch or three and put a single wrap of the aforementioned electric tape around it to make sure it stays put. More wraps will find something to catch on. GENTLY pull both through, exiting between the headliner and door frame.

Leave the tube on the coax. Finish the NMO mount, and use the tube to work the coax behind the door seal(s) to the radio (keep it behind side airbags!). Stay in the roof and run down the A-Column to get behind the dash. Tie the coax clear of steering U-Joints and size 14 boots.

Remove the coax completely and do it again, this time without being wrapped around the wrong side of the door seal. Cut off the excess, install the connector (use solder above VHF or 45 watts), install the antenna and tune it, and go to the next car.

The only times I've had a leak was when I thick-fingered the O-Ring, or had to re-use an existing hole that was bigger than 3/4".

Water is not your friend. Antennas come with a packet of silicon grease for a reason. Use it under both mount and antenna O-Rings and on the outer mount threads. The silicon also keeps the edges of the hole from rusting, making for better contact. Remember that the roof is the other half of the antenna. Some antennas come with an adhesive circle that goes around the mount and sticks to the roof- if the paint is rough or oxidized, it will seal to the roof and give a smooth top seal for the O-Ring.

I never use backing plates, but I do make sure the inside fingers are fore and aft, and stay that way when I tighten the outer ring. They make a special tool for that, but a pair of needle-nose pliers works just fine. That makes the antenna less likely to fall off when (not if) you find a tree limb.

Roofs more than 3/32" thickness require two sided installation mounts, and access to the underside of the antenna. Most car and truck roofs are less than that unless you accidentally find a #$%$#! stiffener.

The center contact of the antenna is critical- make sure you get it right the first time, and unscrew the antenna annually and check for good contact and water.

There is an NMO base antenna available for every frequency and application.

When you trade the truck in, leave the mount and coax for the next guy. That will save both of you time, money and trouble,
 
Last edited:

990adv

Member
Joined
Jan 7, 2010
Messages
138
Location
Central IL
Thank you all for the responses. It is more than I can digest at this time. (Just got off work, brain frazzled)

I will go thru it all when my critical thinking skills are more in tune.

Once again thank you all.
 

ramal121

Lots and lots of watts
Joined
Dec 5, 2008
Messages
1,774
Location
Sonoma, CA
Plus one for everything jeatock said. But the main point is that a UHF mount will require access to both the inside and outside of the roof which requires pulling the headliner down. A NMO mount can be fished through the hole top down with minimal dismantling of the headliner. He likes nylon tube. My preference is a piece of steel drain auger that can be bent to curve anyway I want. A friend swears by speedo cables.

The thing I'd like to add is air bags. Stay away from them as much as possible. If you have to cross one, go behind them as best you can. You don't want a bag ripping open when it's needed most.

The point is, an NMO mount is more common, versatile in antenna selection, and wayyyy easier to install.
 
Last edited:

redshift

Member
Joined
Jan 17, 2011
Messages
55
Location
Eastern WA
Remove the coax completely and do it again, this time without being wrapped around the wrong side of the door seal.
The entire post was great advise, but this sentence was my favorite part. Not that I've done that before or anything. :p

I've also learned a trick -- if you can get the headliner out, that is. In extended-cab trucks where the rear doors open suicide-style, you can usually get the whole headliner out without bending it too much. This makes the wire fish easier, but you will probably pepper your seats and carpet with hot, sharp, little metal shavings from the step bit or hole saw. If you do have the luxury of having the headliner out, tape a garbage bag to the underside of the roof while you are drilling your hole(s). You will spend a lot less time pulling little roof shards out of your legs and arms later.
 

ERICMYERS

Member
Joined
Jul 8, 2007
Messages
248
Location
Plainfield, IL
I buy them by the gross, 2 or 3 times a year. There are brass and stainless, 1GHz and 6GHZ models available, and every flavor of coax known to man- coax choice is more critical than anything else. Don't buy the pre-installed coax connector.

Don't pull the headliner down. Pull (hard) on the upper door seal, and peek under the headliner to find a spot where you don't drill through a stiffener or roof brace. The door seal will go back and reseal fine. Don't pull more than you need for easy access.

Tape measure the center of the roof. Use the inside of the door frames as reference on both sides- car builders don't always get their roof seams straight. Measure and check twice, drill once. Re-check for stiffeners and braces. X marks the spot.

If you are installing on a newer pickup, pull the third brake light out of the back and drill the holl as far forward as you can. 4" from the back tunes fine on VHF, and higher freq's won't care.

Drill an exactly 3/4" hole from the outside, but don't go too deep and into the headliner. If you borrow an electrician's s hole saw, make sure that it will drill a 0.750" hole, and not a conduit-size hole. If you don't have a $150 carbide antenna install hole saw, wrap the outside of a home store hole saw with tape and keep the pilot short to save the headliner. Don't panic if the hole saw wanders just a bit. It's only paint, and the mount will hide it. Watch out for the piece, it's HOT, but not hot enough to damage the headliner. Pull it out lest it rattle for the next ten years.

Get a 3' piece of 1/4" nylon tube (ice-maker water supply tube works great). Put the tube in the hole and work it straight sideways to the door. Have a flashlight handy, and a coat-hanger to reach the nylon tube when it bends the wrong way. Don't panic if you bend the edge of the headliner a bit- they're self healing.

Plain old electric tape will work nicely when you slice a finger open and are bleeding all over the car.

From the hole, slide the coax into the tube an inch or three and put a single wrap of the aforementioned electric tape around it to make sure it stays put. More wraps will find something to catch on. GENTLY pull both through, exiting between the headliner and door frame.

Leave the tube on the coax. Finish the NMO mount, and use the tube to work the coax behind the door seal(s) to the radio (keep it behind side airbags!). Stay in the roof and run down the A-Column to get behind the dash. Tie the coax clear of steering U-Joints and size 14 boots.

Remove the coax completely and do it again, this time without being wrapped around the wrong side of the door seal. Cut off the excess, install the connector (use solder above VHF or 45 watts), install the antenna and tune it, and go to the next car.

The only times I've had a leak was when I thick-fingered the O-Ring, or had to re-use an existing hole that was bigger than 3/4".

Water is not your friend. Antennas come with a packet of silicon grease for a reason. Use it under both mount and antenna O-Rings and on the outer mount threads. The silicon also keeps the edges of the hole from rusting, making for better contact. Remember that the roof is the other half of the antenna. Some antennas come with an adhesive circle that goes around the mount and sticks to the roof- if the paint is rough or oxidized, it will seal to the roof and give a smooth top seal for the O-Ring.

I never use backing plates, but I do make sure the inside fingers are fore and aft, and stay that way when I tighten the outer ring. They make a special tool for that, but a pair of needle-nose pliers works just fine. That makes the antenna less likely to fall off when (not if) you find a tree limb.

Roofs more than 3/32" thickness require two sided installation mounts, and access to the underside of the antenna. Most car and truck roofs are less than that unless you accidentally find a #$%$#! stiffener.

The center contact of the antenna is critical- make sure you get it right the first time, and unscrew the antenna annually and check for good contact and water.

There is an NMO base antenna available for every frequency and application.

When you trade the truck in, leave the mount and coax for the next guy. That will save both of you time, money and trouble,
I nominate this for post of the year - nice job, man. Technically correct, on topic, logical how to, and with perfect amount of tongue-in-cheek humor. spectacular!
 
Status
Not open for further replies.
Top