Permanent roof mount solutions

[rixdafix]

Welp, I pulled the trigger on a McKinley and I think it deserves a proper antenna installation so....
I'm considering a Sirio Performer 2000 for the antenna.
The sheet metal on the roof of a Jeep Cherokee XJ is very thin.
I plan on sneaking at least a 6" x 6" reinforcing plate underneath.
I see pucks but even with one of those, I think I'd need to add a reinforcing plate.
So, if I'm reinforcing already, would I be able to use a more standard mount like this Sirio?

BuyAntenna.Com

BuyAntenna.Com

www.sirio.store

 

[mrweather]

A permanent NMO mount and something like a Larsen NMO-27 antenna will always be a solid performer.

 

[prcguy]

If the roof sheet metal is really flimsy I would put a backing plate in and make it a reasonable size to spread the load out, at least 6-8" square or round and at least 16ga .060 thk steel or .125 thk 6061-T6 aluminum. I would also coat the top side of the backing plate with a paste type Epoxy so it adheres to the underside of the roof.

An NMO is designed to go into thin sheet metal and a standard 3/4" hole mount may have problems with double layers but there are special mounts for thick materials. If you were to put on something larger or heavier like a big Firestick I would go even thicker and larger on the backing plate.

I'm not familiar with the Sirio mount but if it will fit through double thick sheet metal it should work fine.

 

[rixdafix]

I hadn't really considered NMO mounting as all the antennas I've considered are for SO-239 mounts but NMO looks like a sturdier design. Might be the way to go. Thanks for the suggestions and I hope everyone had a good Thanksgiving.

 

[rixdafix]

Dropped the dome light and found this awesome surprise. Really stout support that actually spans the width of the roof. NMO mount will go right in the middle of the hole with an appropriate plate to draw the whole assembly together. Time to scrape some paint off the underside...

 

[prcguy]

You would want any mount to go through and include the brace material. If the roof is really thin and you put an NMO or other mount just through the middle of the brace it can still bend and buckle the top sheet metal. You need to both stiffen the top layer and spread the load out over a larger area to reduce the chance of damage.

View attachment 131716

Dropped the dome light and found this awesome surprise. Really stout support that actually spans the width of the roof. NMO mount will go right in the middle of the hole with an appropriate plate to draw the whole assembly together. Time to scrape some paint off the underside...

 

[mastr]

FWIW- there are other options besides the standard NMO style-the below is a random picture I found of the 3/8" or 3/4" style.
You can drill a 3/8" hole and use a backing plate- much more stable results.

3/4 or 3/8 Inch NMO Mount for Thick Roof (adjustable up to 1/2

Features: • Can use 3/8 or 3/4 hole• Adjustable NMO Locking Nut for 1/8-1/2 Inch Roof• All Brass and Stainless Steel Components forMaximum Reliability and Corrosion Resistance• Non-Rotational Heavy-Duty Centering WasherEnsures Perfect Hole Alignment while

www.arcantenna.com

 

[rixdafix]

You would want any mount to go through and include the brace material. If the roof is really thin and you put an NMO or other mount just through the middle of the brace it can still bend and buckle the top sheet metal. You need to both stiffen the top layer and spread the load out over a larger area to reduce the chance of damage.

Absolutely, that's why I'm going to span that whole surface with a large plate with a hole in the middle that draws the whole assembly (mount, roof, brace structure) together as I tighten the mount in place. Should be pretty solid.

FWIW- there are other options besides the standard NMO style-the below is a random picture I found of the 3/8" or 3/4" style.
You can drill a 3/8" hole and use a backing plate- much more stable results.

3/4 or 3/8 Inch NMO Mount for Thick Roof (adjustable up to 1/2

Features: • Can use 3/8 or 3/4 hole• Adjustable NMO Locking Nut for 1/8-1/2 Inch Roof• All Brass and Stainless Steel Components forMaximum Reliability and Corrosion Resistance• Non-Rotational Heavy-Duty Centering WasherEnsures Perfect Hole Alignment while

www.arcantenna.com

Thanks for the link. I already decided on using a 3/8" hole since I can do this from underneath.

I sure appreciate everyone's suggestions, thanks!

 

[slowmover]

Breedlove Mounts

A fine line of offerings. I recommend taking the long way thru their catalog given your ideas.

I’m using the #601 with 6X6 backing plate on my Dodge pickup (shown as example only). I wanted the option of using largest antennas.



7’ PRESIDENT Texas 1800


Permanent roof mount is certainly worth the effort. Tested against the triple mag I used before it’s a clear winner in Noise and Range.

I added a Palomar Engineers Coax Feed Line Sleeve Choke I’d purchased earlier for a big truck experiment. Have used that roof rib to attach. This or the CMNF 500 Transceiver Noise Filter quiets what’s present coming down the antenna.

Mines not done, but this is the example from which I’m working.


.

 

[slowmover]

Missed the edit window:

I’m using a PRESIDENT Lincoln, and, as with other “digital” radios the RX is characterized by hash. The filter and/or choke quieted that substantially. Other vehicles can substantially screw with RX while moving down the highway. (Coax is about 5’ long as a result).


If ceiling mount appeals:

The radio is screwed thru the headliner to a 7X12 wooden board epoxied to the roof. Here it’s shown in mock-up with Liberty wireless mic readied plus a W-M 4005 RigRunner (which has some DC noise filtering).



Enough room also to add an outboard WEST MOUNTAIN RADIO CLRSPCH DSP MODULE to run the KENWOOD KES-5 under the drivers seat now that I’ve changed to a different distribution set-up.



DSP is the game-changer. Integrated Speaker or Module, consider it a necessity.

I was going to use 10-AWG, but changed to 6-AWG. It comes up passenger A-pillar along windshield header. (Neg to that).



Ceiling Mount is sorta hidden. Passersby don’t expect to look there is my take on being parked.

Antenna & Radio removed it’s quite good for stealth.

Sirio on a Breedlove mount:

 

[rixdafix]

That's a nice setup, thanks for sharing. I was actually looking at the #601 mount until I saw the structure of my roof. I've got a plan lined out for that now. I also entertained the idea of ceiling mounting the radio but there are also double din kits for the XJ that are really slick.

Once I get the McKinley (Monday delivery!) I'm going to see how it fits in the dash with my single din stereo head unit. If I can keep them separated enough for good cooling then I might go that route. I'll never have them in use at the same time so heat shouldn't be an issue unless their playing Jerry Reed then everyone on 19 within range might hear it. I do like the short coax run that a ceiling mount provides...

The ole Jeep is a bit noisy on the highway and a DSP might prove a necessity but I'll see how that little front fire speaker in the McKinley does first. The Sirios are nice. I was looking at the P2000 but so many low hanging limbs where I travel daily... The Larsen NMO27 I ordered isn't exactly a stubby but it might sneak by under a lot of what the Sirio would smack hard.

Good stuff

 

[jeepsandradios]

Installed many NMO mounts in the XJ with Lowband antenna's and never had one pull out. I would just drop a standard NMO mount in it and grab the larsen antenna. Simple. done.

 

[Project25_MASTR]

My XJ...

I run CB on the fender with the Larsen NMO-27B. The roof has a Larsen NMOQB with spring cut to 19". That antenna setup has been on there for over a decade though (did a full redux of the comms gear inside two years ago now, don't know if I posted) on a Jeep hasn't been driven on pavement in a decade now.

 

[slowmover]

That's a nice setup, thanks for sharing. I was actually looking at the #601 mount until I saw the structure of my roof. I've got a plan lined out for that now. I also entertained the idea of ceiling mounting the radio but there are also double din kits for the XJ that are really slick.

Once I get the McKinley (Monday delivery!) I'm going to see how it fits in the dash with my single din stereo head unit. If I can keep them separated enough for good cooling then I might go that route. I'll never have them in use at the same time so heat shouldn't be an issue unless their playing Jerry Reed then everyone on 19 within range might hear it. I do like the short coax run that a ceiling mount provides...

The ole Jeep is a bit noisy on the highway and a DSP might prove a necessity but I'll see how that little front fire speaker in the McKinley does first. The Sirios are nice. I was looking at the P2000 but so many low hanging limbs where I travel daily... The Larsen NMO27 I ordered isn't exactly a stubby but it might sneak by under a lot of what the Sirio would smack hard.

Good stuff

DSP is for what the radio can’t filter. What Amateur level radios include. What your radio can’t make it legible to you.


I’ve had the integrated speaker in the big truck for over eight years now. Much more than 500k miles. Needs Audio + 12V. Means I hear and can converse with those that them around me can’t make out or hear at all.



I could run a PRESIDENT Randy handheld and have “better performance” on AM than your choice given DSP. (I like the McKinley well enough I gave one to my son plus a Sirio 5000 for his 4-Runner.

An RM Italy KL-203 is the other item I wouldn’t be without while mobile. AM or SSB. That little bit does a lot.

The pair makes for close enough to state-of-the-art. Sufficient unto the task.

 

[rixdafix]

And so it begins...

 

[rixdafix]

That wasn't so bad. I may need to trim a little more off the whip, it's at about 47" which is what Larsen calls for. SWR is around 1.4:1 using the built in meter on the McKinley. I'm using a 12 foot length of RG-58A/U which I already had.

Drilled the hole, ground off the paint, star washer sandwiched between the roof and big fender washer for good contact. Everything came together real nice when I tightened the mount down and it's very sturdy.

I wanted to run the fat rubber gasket that came with the Larsen coil but it would only allow about half a turn on the mount threads. With the o-ring all is well.

I made a local contact on 19 AM with excellent report and an awesome 2 minute long contact with 754 Southern California after answering his CQ on 37 LSB. He knew I was on a President before I told him and loved the fact it's a barefoot rig lol. I'm very pleased.

I'd like to get that SWR down a little more. Since the radio is mounted to my plastic console, should I run a ground strap from the radio chassis to ground under dash? Not that this will help my SWR but it was something I was pondering.

As per the President installation instructions, I wired both power leads directly to the battery. I always disliked how supplied power cables have the fuse close to the radio instead of at the battery. I'm going to add one in line at the battery.

Thanks to everyone who chimed in on this project, it was very helpful.

Happy holidays, Rick (561 Missouri)

 

[mmckenna]

That wasn't so bad. I may need to trim a little more off the whip, it's at about 47" which is what Larsen calls for. SWR is around 1.4:1 using the built in meter on the McKinley. I'm using a 12 foot length of RG-58A/U which I already had.

Drilled the hole, ground off the paint, star washer sandwiched between the roof and big fender washer for good contact. Everything came together real nice when I tightened the mount down and it's very sturdy.

I wanted to run the fat rubber gasket that came with the Larsen coil but it would only allow about half a turn on the mount threads. With the o-ring all is well.

I made a local contact on 19 AM with excellent report and an awesome 2 minute long contact with 754 Southern California after answering his CQ on 37 LSB. He knew I was on a President before I told him and loved the fact it's a barefoot rig lol. I'm very pleased.

Looks like you did a good job. You should be pleased.

I'd like to get that SWR down a little more. Since the radio is mounted to my plastic console, should I run a ground strap from the radio chassis to ground under dash? Not that this will help my SWR but it was something I was pondering.

Unlikely that will impact your SWR.
But, it's always a good idea. There are various scenarios that can result in less than ideal performance when you rely on the long negative lead or long coax shield to ground the radio. Running a strap from the metal radio chassis to body ground, and keeping it as short as possible, can sometimes help. Give it a try and see if it helps. Usually it will not hurt.

The cut charts for the antennas will usually get you pretty close, but since each vehicle differs a bit, it's still a good idea to tune it for your specific application. If it's showing 1.4:1 on your first try, it showing you did a good job on your install. Bringing that down lower shouldn't take much work.

As per the President installation instructions, I wired both power leads directly to the battery. I always disliked how supplied power cables have the fuse close to the radio instead of at the battery. I'm going to add one in line at the battery.

I'd disagree with that. But it's usually 'safe', especially when selling a product like a CB where you never know what kind of equipment it is going to be installed in.
For a vehicle like yours, you'd be better off running the negative lead directly to body ground, as close to the radio as you can get it.
Some newer vehicles have sensors on the negative strap at the battery. The manual for the vehicle will usually tell you NOT to connect negative directly to the battery as it allows the sensor to be bypassed. I do not know if a 2000 Jeep has that or not. But again, not doing yourself any favors with long ground connections like that.

 

[slowmover]

Great pics! Thx for those

Shortest distance to 12V ground. Test with DVM for under 3% voltage drop on key-up. 1.4:1 across all 40 is leave-it-alone. Time with some RF bonding next. Then see if changes.

A worthy rig will do 10-12/miles without issue in daylight in semi-rural. (5-7 in major metro). Find a high spot that’s quiet and see what kind of distances you’re getting heard from an Interstate or US Highway with commercial traffic.

1-3/miles is inadequate warning distance when one needs to respond to clarify details. TX & RX need to have a fairly close match in distance. (Thus a KL-203 & DSP in audio).

STL has plenty of commercial traffic. The LOVES Truck Stop at Sauget, IL is an ideal test spot. An oasis I nearly always use to skirt traffic en route from Chicagoland back to Ft Worth via IH-44.

That stretch of road from Loves across the River to 44 always has AM-19 traffic available to Hear, and Get Heard as going thru STL on 70 has the peril of traffic snarls.

The Rand-McNally Motor Carrier Road Atlas (at the Loves Fuel Desk) is useful for all traffic in this country, and the STL metro is well laid-out showing Mile Markers whereby you shouldn’t have any trouble determining radio air miles no matter which road your respondent is traveling.

Be upfront about what you’re up to (ignore Beavis & Butthead), and use 19 at that Loves (which will interest the drivers) to do the initial set of checks.

“Audio Quality” (Mic Gain), the usual play a little dumb stuff to show you (any of us ) are looking to accept help is a good qualifier.

That stretch of road I’ve spent close to an hour working with others about radio settings (wrote about it in other posts). You’re lucky to be at one of the major North American interchanges. Just get a ways out one of the many routes versus staying inside the loop around the city.

Everyone wants to sound good. I learned a lot about the rig I had that day.

From the exit of the 255 bridge into IL to the Loves is right at ten air miles and is flat & open. One should be able to Hear, and Be Heard across that stretch parked at the Loves.

Drive around back with the big trucks and park nearest the highway edge out-of-the-way. Weekday morning.

LOVES #758 Sauget, IL
IH-255, X15
.

 

[slowmover]

If you then leave Sauget and proceed to IH-44 and head out of town, the directionality of big truck radios will become starkly familiar.

After a U-turn and headed back, the same phenomenon will alter slightly as to “who” you can and cannot hear, again, due to the same cause.

The locals (or regionals like BEELMAN) may be on their own CB channel. Use Scan function if you run 70 or 55 into IL.

Try to figure out how far ahead you can be heard by those in the same direction of travel.

Early disaster warning is predicated on who is out ahead of me.

I’m more likely to hear farther the guys in the opposite direction of travel.

Overcomimg the deficiencies of the other mans radio rig really is the only game.

.

 

[rixdafix]

Good info on the grounds, I'll shorten the radio ground proper and bond the radio chassis as well.

Speaking of grounds, I got to thinking of that fender washer I used. I installed it as is and I wonder if it has some kind of zinc coating and if that affects conductivity enough to be of concern. Perhaps I could grind the coating off if so or use a washer of different material...

From the exit of the 255 bridge into IL to the Loves is right at ten air miles and is flat & open. One should be able to Hear, and Be Heard across that stretch parked at the Loves.

I travel through that area on occasion when I go to the salvage yards over there I'll have to give it a try.

I actually live west of St Louis in St Clair, MO and commute 28 miles of hwy 44 into St Louis County every work day but it's pretty hilly in that stretch so not the ideal range test.