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Here’s an Evo I was running 5-years ago when they first came out. Talked all over depending on what radio I was using. (6’ Firestiks shown, changed to 7’ Skip-shooters which is what it can use best )
You are correct the molded-in-place HIRSCHMANN
Thin Film Antenna is pretty much worthless.
The question then becomes about the antenna mount, antenna, and the coax.
First I’ll outline a decent system. Then near bottom where to start where you are now:
1). The type shown (a version for the earlier models available) is what you want.
Won’t rotate like the clamp bar type (which also don’t ground well)
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2). You’ll need to run some 3/4”W woven copper braid to
structural steel at the A-pillar at the hood closure line. From a bolt where the paint behind it is cleared off.
3). How is the coax being run? The best solution is one of two ways:
A) Thru an unused air line hole into the engine compartment (I use a cable gland to seal both ends); or,
B) Behind the A-pillar kick panel and out thru the grommet that carries the door wiring. Then eased thru hood vent.
— There cannot be a pinch point affecting the coax. Not even once.
WILSON makes an RG8 (Mini-8) cophase harness with FME ends that makes threading the coax very easy. Screw-on ends. It’ll work well with a
dash-mount radio which avoids removing the A-pillars to get overhead access (I spent hours and several hundred dollars with one of the most experienced installers to run to the overhead
and it just wasn’t worth the difficulties).
POWER: You can run the DC-positive and Negative to the Fuse Panel leads,
it’s just as quiet as going to the batteries. Fuse the Positive, not the negative. Use 12-AWG tinned copper marine grade wire.
Cables: Install split-loom convolute cover over every foot of coax and power in appropriate size. Bundle excess coax in figure-8 skein over a foot long. Zip tie.
Radio: A good radio choice. The AM/SSB Uniden is the number one basic radio. Using factory mounting bracket, install “industrial” Velcro underneath that
and to back edge of radio to glue both to dash-top. (Lowes or HD, not the truckstop stuff). Tilted and angled towards driver. (If you can use a flat buckled strap, so much the better; see FL options)
Mic: With an Astatic 636, use a GEARKEEPER mic hanger and attach D-ring above it (screw it, don’t sweat this part) so that it’s easy for you to grasp while driving, yet retracts out of the way
and won’t bang on anything.
Speaker: A Uniden BC-20 is the easiest to acquire low-cost option in performance.
Install it above driver in the bin above door by zip-tying to the shock cords and with Velcro.
Extend the audio line as needed to come down A-pillar (stuff into gap), and route to radio (more split loom).
Antenna: You have the wrong “type”. You want a
top load antenna 6-7’ tall. (Skipshooter brand, IMO). The antenna you are using is quality,
but not in that location. Keep it for your personal vehicle.
The 7’ will get above a van, but not cause clearance problems (be careful anyway).
The terrible SWR is the wrong antenna, mount, damaged coax, and lack of good connection to the truck chassis (todays trucks have a lot of glue, metal contact not always enough). Needs an
RF Bond.
The U-980 has a decent SWR meter. But a truckstop external meter is your backup. Will need a short coax jumper to go with it. Directions for use on packaging and widely over Internet.
What is SWR (Standing Wave Ratio)
Before the above,
test:
Change antenna to any 5’ Fiberglas top load. Keep directions to adjust tip for SWR (don’t transmit (speak). Any reading below 2.0:1 is okay, and 1.5:1 is great. (Keep this as a backup after getting the 7’).
— Check that the coax terminations aren’t loose, and that both ends are threaded correctly. Finger snug tight, BUT as far as they’ll go on.
— Try another piece of coax from radio to antenna if that’s not helping. (Doors shut while testing, run thru window opened). Just trying to see if original coax was damaged (ohm meter test first before buying more is best as in post above mine).
Expect that coax was damaged, first,
and that antenna mount isn’t grounding the coax shield adequately, second.
Do the rest of the above as you go along. See my other posts for upgrades.
A Cascadia is much the easiest of the fleet tractors to make work well.
You’ll be glad you did. The more you do (as above)
the better it will get.
Antennas, Mounts, and Coax are the priority.
Mobile Radio Pro
.
