Rugged Radio Antenna

[Kzneft]

I really can't get an answer to my question from Rugged Radio so I will post it here as I am sure there are lots of smarter people here then me when it comes to antenna's...
Have a Rugged radio in my SxS and get almost no distance when transmitting (Like 100 feet). I checked my cable from my Rugged Radio to my antenna, and it looked like it got very hot and noticed some melted shielding. I know I need to replace the cable, but I thought maybe I would check the antenna to see if there was a short or something that might have caused the cable to get hot in the first place. I put my continuity tester between the antenna and my frame (ground) (see pic), and yes there was a connection. I thought that was odd. I then checked the connection between the antenna and the center of the connector that is supposed to connect to the center wire on the coaxial cable, and it was an open circuit. Isn't there suppose to be continuity between the center pin and the actual antenna, but no connection between the antenna and ground?

 

[Project25_MASTR]

Depends on the antenna design. Only way to really test is to either grab another antenna and see how it performs or test the return loss of the antenna.

 

[mmckenna]

Half wave antennas like that will often show a short between the ground and the whip as the coil passes DC.

As for connection to the whip, there may be a capacitor in there, but like ^^he said above^^ it depends on the exact design.

 

[mmckenna]

If you are looking for a replacement, I've been running these on top of a few UTV's successfully:

Laird TE Connectivity B1442NS VHF 144-174 MHz No Ground Plane Antenna w/ Steel Spring

Laird TE Connectivity B1442NS VHF 144-174 MHz No Ground Plane Antenna w/ Steel Spring

theantennafarm.com

I haven't used this antenna specifically, but I've found EMWave to be an excellent brand and worthy of a try:

EM Wave EMFLX-M10004-GPI VHF 132-174 MHz (tunable range) No Ground Plane Antenna, e/m-Flex® Poly spring

EM Wave EMFLX-M10004-GPI VHF 132-174 MHz (tunable range) No Ground Plane Antenna, e/m-Flex® Poly spring

theantennafarm.com

 

[speedway_navigator]

NanoVNA | Very tiny handheld Vector Network Analyzer

Very tiny handheld Vector Network Analyzer

nanovna.com

Like P-25 said, the DC part of an antenna system does not tell the RF part of the story. A vector network analyzer (VNA) shows resonance or how effective the antenna is at radiating RF. Your range testing indicates you have a problem which could be most or all of the power is reflected back to the radio.

Most commercial grade radios will detect this and limit TX power to protect the radio and prevent what we RF geeks call spurs or spurious emissions which can generate RF energy on other freqs.

Your mount might be the problem, did you try continuity from the center pin of the coax connector to the whip? (preferably with it on the mount, not like your photos....)

Maybe the pin on the coil is not touching the mount.

Never assume nothing, poor grammar but makes you think.

 

[nokones]

I agree with the two above antenna recommendations, but in the meantime, let's identify the true source of the problem why you are only getting 100 feet of operating range. If the problem is not with the actual antenna, swapping out the antenna will not resolve your problem so lets not spend any money yet.

What freq are you trying to communicate on? What are your VSWRs? How much of reflected power are you getting with an inline RF watt meter? Have you checked the RF output power of the radio and what is that reading? What is the power output rating of your radio? You should be checking the radio output power with a dummy load that measures out at 50 ohms and rated for your radio output power.

Get an antenna analyzer. Put the antenna back on the mount and check the freq center resonance of the antenna, then run the cable loss check. Let us know what you get.

After those two checks and if the antenna center freq resonates very near your operating freq, with your multi-meter perform a continuity check to see if there is any continuity between the coax center conductor and the outside of the coax connector. You should not have any continuity and your reading should be "OL" or "0.00". If you have a reading you may have an itty bitty coax braided strand shorting out with the connector from a sloppy connector install.

FYI - I haven't had very good luck with Rugged Radios antennae in the past. They are a hit & miss. On more than one occasion, I have found some of the UHF Rugged Radios antennae centering out around 300 Megs.

Let us know what your findings are?

 

[G7RUX]

"Melted shielding" is very unlikely to result from transmitting at any non-crazy power level so I would be having a look at the DC vehicle grounding. It is entirely possible that there is a bonding problem somewhere and significant current is being carried to ground via the coax screen, perhaps leading to the issue you identify. This sort of thing can also lead to apparent deafness in the radio as many antennas show DC continuity between their pin and ground due to the feed arrangements.

One place to start is the engine earth strap, but any and all bonding should be examined. This is why in a vehicle the negative lead from the radio should run with the positive back to the battery but NOT connect to it directly; use a nearby earth point and do not use a fuse in the negative line.

 

[nokones]

Most radio manufactures strongly recommend running the radio ground lead directly to a factory chassis grounding point on all late model vehicles bacause of the various vehicle control modules. But in the OPs case with a Side X Side in play, the radio ground lead may be best directly to the battery.

Check the antenna mount to see if there is any grounding continuity without the antenna coax connected to the radio to ensure that the mount has a grounding bond.

 

[G7RUX]

Most radio manufactures strongly recommend running the radio ground lead directly to a factory chassis grounding point on all late model vehicles bacause of the various vehicle control modules. But in the OPs case with a Side X Side in play, the radio ground lead may be best directly to the battery.

Check the antenna mount to see if there is any grounding continuity without the antenna coax connected to the radio to ensure that the mount has a grounding bond.

Direct to the battery is always unwise; in the event of a grounding loss (eg: engine earth strap) there is a significant liklihood of large currents travelling to ground via the radio set itself.