proper coax choke mobile..

[Shadetree Mechanic]

The 1:1 balun will cure problems like the "Hot Microphone" problem I had.
One CB'er came by my shop and told me when He keyed His radio up the traffic lights would switch over to four way flash. I had to see this for my self and we took a ride.
Sure enough when he keyed up the lights went to flash.
When we got back to my shop I checked his system. Opened the trunk and there sat a Texas Star 1600 DX. I asked if I could look inside the radio. He said not today. I asked if he had it tuned the answer was yes.
I told him to wrap eight turns of RG-213 around an 8" pvc pipe. and check it again.
Problem fixed. He stopped back after he tested it out and gave me $50.00 for my trouble.
I was amused at him going on about how I had control of some magic.
Not magic, just training.

I bet people would pay big money to be able to mess with the traffic lights! The Spurs that thing put out must have been horrendous.

 

[Tallman]

I bet people would pay big money to be able to mess with the traffic lights! The Spurs that thing put out must have been horrendous.

I didn't have the chance to hook it up to the spectrum analyzer and I bet you are right.

 

[Slowmover]

There was a brief window a pair of decades back before the transmitters used by FIRE, etc, to change lights to green wasn’t yet barred to commoners.

One can posit that was a bit of fun with following traffic. Pied Piper of Hamlin ain’t got nothing on this at afternoon rush hour.

.

 

[Slowmover]

Was reviewing this as hope to figure out how to pop off interior panels to access backside of Peterbilt twin antenna mounts.

Have a pair of ft240-31 toroids already.

Have ordered also some snap-over types to go with a gennywine Wilson Mini-8 Co-phase Harness bought years ago. 18’ and THE CHOICE OF TRUCK-STOP CB EXPERTS EVERYWHERE!!

But, first, see if the factory coax can be “improved”. The coax is completely within the console above the drivers head. Sort of, A-pillar to A-pillar. It’s short, too. So, also hoping I can get five turns.

(Mobile note: No, there’s almost no sheetmetal at all in a set-back axle company-spec tractor. There’s a honking big cast-iron 4,000-lb prime mover under the hood, but metal is only for what can’t be injection-molded.)

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[Slowmover]

To continue from last post; (had to drive off that day). Have since learned access from interior ain’t happening.

But I may try removing exterior of antenna mount to see if I can fishtape coax thru

The cophase harness is RG8X. (Wilson Mini-8 @ 18’ with FME ends)

Am going to use an FT240-31 toroid nearest each antenna feed-point.

Once this gets installed it ain’t coming back out.

Q: The info I find is to not use a smaller diameter with RG8 than 2.5” to coil. K0BG recommends 3.0”

1). (12) wraps where: it’s (6) then crossover and do another (6), and coax leads are on opposing sides.

2). This morning I’m thinking of how to attach the coax to the ring and using zip ties (not too tight) is closest I come.

Maybe adhesive tape over & under afterwards. (Hmm)

These will be inside truck shell, where neither weather nor appearance are a problem.

The balance of coax not needed will be skeined together out of the way.

A PALOMAR Cube Choke at opposite end (before amp to radio; max 100W).


— How would you solve attachment of coax to toroid?

Thx



.

 

[Slowmover]

Well, . . after about ten feet of each coax leg was formed to consecutive 3.0” loops, I was JUST able to fit (12) turns.

Bought this Wilson coax sometime in the past eight years. About $40/retail. The toroids about $10. So, a fifty-dollar harness.

Not yet brave enough to pop that outer antenna mount cover off, as the HOS 34-hr reset also demanded housekeeping which was priority. Another day here (and no rain) and I would have gone ahead. So, until then . . .

 

[Slowmover]

Well, . . after about ten feet of each coax leg was formed to consecutive 3.0” loops, I was JUST able to fit (12) turns.

Bought this Wilson coax sometime in the past eight years. About $40/retail. The toroids about $10. So, a fifty-dollar harness.

Not yet brave enough to pop that outer antenna mount cover off, as the HOS 34-hr reset also demanded housekeeping which was priority. Another day here (and no rain) and I would have gone ahead. So, until then . . .

View attachment 36173

Continued past the point above and re-did.
Now, (4) FT-240-31 toroids in total; at each end of 18’ legs.
(4) chokes of (9) 2.5” turns each.

Have had this monster crawling around in a bag in the big truck a few months. Finally decided I should get some adaptors to fit the back of the mount (Male Mini-UHF/SO-239) as that prevented installation when mount removed for investigation. (But fishing thru new coax won’t be hard).

At least the toroid-wrap at each end of each 18’ leg has brought those down to but a few feet in length, so it’ll be MUCH easier to install versus bundling 14’ of coax.

Maybe it’ll even help.

A failed factory crimp rendered factory harness useless, so have tried a spot mirror mount. Better, and worse.

In lieu of the next hare-brained antenna mount, this’ll do.

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[loosecannon]

Slowmover,

I wish i'd seen this thread earlier, i would have told you to just buy the snap on ferrites.
mix 43, or 31, either (among a few others i cant remember) will work fine.

the deal is you have to use like a foot worth or so.
but at least you don't have to coil the coax!

i've bought them straight from Amidon and i don't think it was that expensive.

obviously your way will work too, just sucks to have to deal with all that coiled coax.
LC

 

[Slowmover]

Slowmover,

I wish i'd seen this thread earlier, i would have told you to just buy the snap on ferrites.
mix 43, or 31, either (among a few others i cant remember) will work fine.

the deal is you have to use like a foot worth or so.
but at least you don't have to coil the coax!

i've bought them straight from Amidon and i don't think it was that expensive.

obviously your way will work too, just sucks to have to deal with all that coiled coax.
LC

I buy snap-ons by the dozen. But (as I understand) it would take many snap-ons to equal the toroid-wrap.

The crazy looking cophase harness I’ve put together is wholly installed inside of a cabinet. It’s not entirely free space, but the overhead console in this Peterbilt.

Not under a headliner.

From the drivers perspective, the unit has a number of cubbies in which to store stuff. Between (and around and over or under) is plenty of room for what I’ve concocted.

Thanks for your advice (concern).

Happily, this was a GREAT way to use up 36’ of coax in a space approx 7’ across.

MAYBE it will work.

In fact, there’s enough room I might try a pair of MFJ-915.

.

 

[ForestRunner98]

I just saw this thread!!

I made a choke using the 2017 chart from Karinya and I am experimenting with a 61 mix core. I have it wrapped 12 times cross wound in the middle. It should have about 8k of impedance (resistive black bar) at 27 MHz.



Not sure about putting it under the headliner. Don’t want that to touch the roof and melt. Also it shouldn’t any metal. I will leave it there for now.

So far I am able to raise the RF gain with lots less hash. If I go 3 clicks less the signal drops BIG. So it’s doing it’s job. This is just driveway readings. So when I get on the road I will see how well it’s working.

 

[Slowmover]

Just wrapped an FT-240-31 toroid for the sons new SIRIO 5000 mag mount a few hours ago. (8) turns, each zip-tied.

Officially joined Sock Club by cutting one open and encasing the choke to prevent paint damage (three zip ties).

Used a Velcro strap (zip-tied to coax) once measurements set. That strap attached to roof rack. Aerial removed, the coax is wound and thusly secured.

Across the McK built-in speaker the noise was low for a “digital” radio.

He has to boogie out of here in the early a.m., and I have to say, man that antenna lookef sharp as he drove off!

Told him that were he to pass me on the road I’d key up just to ask the owner about his radio rig.

Appears to be 12.5’ clearance.

McK + S-5000 & KL-203.

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[Slowmover]

I just saw this thread!!

I made a choke using the 2017 chart from Karinya and I am experimenting with a 61 mix core. I have it wrapped 12 times cross wound in the middle. It should have about 8k of impedance (resistive black bar) at 27 MHz.

View attachment 45084

Not sure about putting it under the headliner. Don’t want that to touch the roof and melt. Also it shouldn’t any metal. I will leave it there for now.

So far I am able to raise the RF gain with lots less hash. If I go 3 clicks less the signal drops BIG. So it’s doing it’s job. This is just driveway readings. So when I get on the road I will see how well it’s working.

Had it several days now. Worth the trouble?

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[ForestRunner98]

Had it several days now. Worth the trouble?
.

Yes definitely! I am able to keep the RF gain at a higher position. Don’t get me wrong there is still lots of noisy spots around town but the choke makes it more tolerable.

I did make one with a mix 43 toroid and that worked good but the 61 mix is better in my application.

Just like anything else YMMV.

 

[Slowmover]

Great! Thought that’s what you’d said elsewhere and figured this thread needed the affirmation for men to try it.

Mix-31 is the other. The one usually directed. M-61has worked very well in the Peterbilt, where, I suspect vehicle electronics are also a noise cause. M-31 is mainly what I have (dozen-plus in shapes & sizes). So I use both as GP.

Latest is that I’m using the P-E “Line Isolator” (plastic housing) at each antenna feedpoint. Waiting to get into another truck, first.

Son reported the M-31 we wound for his mag mount seemed a help in NOT having local problems affect his RX (installed directly behind mag base).

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[ForestRunner98]

Great! Thought that’s what you’d said elsewhere and figured this thread needed the affirmation for men to try it.

Mix-31 is the other. The one usually directed. M-61has worked very well in the Peterbilt, where, I suspect vehicle electronics are also a noise cause. M-31 is mainly what I have (dozen-plus in shapes & sizes). So I use both as GP.

Latest is that I’m using the P-E “Line Isolator” (plastic housing) at each antenna feedpoint. Waiting to get into another truck, first.

Son reported the M-31 we wound for his mag mount seemed a help in NOT having local problems affect his RX (installed directly behind mag base).

.

The 31 worked for him..awesome!! I figuered I would experiment with the different mixes by using that chart. 43 shows 4K of impedance and 61 8k on 11m. I still have the Palomar CMF choke at the receiver side.

It’s a matter of trying different things. Some stuff work for one application but not for another. But I did notice that mix 61 toroids are more expensive than 31 or even 43.