May 31, 2020, 03:11:22 am

Handheld Antenna Questions

Started by Falling Hare, February 06, 2019, 07:36:46 pm

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Falling Hare

I have started working in communications, which is a totally new and interesting field for me.  The problem is that I have zilch knowledge of radio/communications hardware or even basic electronics.  Have been using the old EF Johnson 5112 (version 4) handheld to get experience in voice communications on local Wing nets.

The other day a 'ham' showed me how to attach a home-made antenna to the hand-held that almost doubled the performance & range.  It is simply a wire about 18" long attached to a washer and inserted in the antenna well and then screwing the whip back into it's fitting.  It works great but looks really funky; and I am while I am careful attaching it into the fitting I am concerned that it may be damaging the equipment in some way.

My questions are:

-Is there an aftermarket longer whip antenna that would work just as well and replace the standard 8 ½" whip antenna.  Have tried a Baofeng NA-771 whip which fitted nicely but simply did not work.  Can anyone recommend specific brands, brand numbers, etc.? (links appreciated).

-Would love to use this in my car (it gets cold up here in the winter) so could anyone recommend specific magnetic roof antenna assemblies that would fit the EFJ 5112 (ver.4)?  Complete out-of-the box assemblies would probably be best for me since you have probably forgotten more about electronics than I will ever know. (Again, links appreciated).

The improved performance of the field expedient wire saves me having to drive 30 miles in to use the squadron base station when I have to get on the nets; would love something that looks more normal but gives me the improved range.

Al Sayre

It sounds like what you are doing is effectively increasing the ground plane of the existing antenna.  Be aware that modifying or changing the antennae that were tested and approved when the radio was licensed by the manufacturer can potentially put you in violation of FCC regulations by increasing the Equivalent Isotropically Radiated Power (EIRP) when transmitting.  Also, if done incorrectly, can damage your radio transmitter if the resulting Standing Wave Ratio (SWR) is excessive.  Suggest you check with your Wing Communications Officer before you do this with any CAP owned radio or operate a modified radio on CAP Frequencies.
Lt Col Al Sayre
MS Wing Staff Dude
Admiral, Great Navy of the State of Nebraska
GRW #2787

Slim

Unfortunately, that's a no-go.

Our radios are type accepted/certified by the NTIA as either a handheld/portable or mobile.  Attaching an external antenna to a handheld and using it as a mobile would invalidate the certification of the radio.

What you're suggesting is just fine in the HAM world, where radios aren't certified/type accepted, and experimenting is allowed/encouraged.  Unfortunately, CAP falls under the realm of professional land mobile radio, where tolerances are much tighter and more restrictive.

All that being said, would anyone really know?  In all likelihood no, and I'll admit to doing it myself with personally owned LMR equipment on a short term basis.  There are ways to properly do it, and there are adapters available that will screw into the SMA antenna port and convert it to a BNC connection.



Slim

SarDragon

Also, adding an external antenna to a portable radio for use in a vehicle effectively turns it into a mobile radio, which usually has different performance specifications that the basic portable might not meet.

Here's an FAQ from the CAP Comm site:

QuoteCan I use a compliant VHF-FM handheld radio as a compliant mobile or base?

A radio is classified by its use, and the NTIA specifications are different for handhelds and mobiles/bases. If you use a handheld as a mobile/base by connecting it to an external antenna, etc., then it must meet the specifications as a mobile or base. Some handhelds do meet these requirements. It should be noted that if you add an external RF amplifier, then the combination is not compliant unless the manufacturer has published compliant specifications for that specific combination.
Dave Bowles
Maj, CAP
AT1, USN Retired
50 Year Member
Mitchell Award (unnumbered)
C/WO, CAP, Ret

Eclipse

+1 to the above.

Operating a transmitter with an incorrect antenna can ruin the device and likely breaks NTIA rules.

Baofeng is a 4-letter word in CAP parlance, just FYI.

Hams do many things that are "good iders" which are not allowed for CAP members.

If a Wing Commo with a loose hair got wind of what you are doing, you would likely be directed to turn-in any
issued corporate owned-equipment.

Review the rules in the ICUT training regarding modifying CAP radio equipment.



Eclipse

Quote from: SarDragon on February 06, 2019, 09:09:42 pm
Also, adding an external antenna to a portable radio for use in a vehicle effectively turns it into a mobile radio, which usually has different performance specifications that the basic portable might not meet.


A different license as well.



Falling Hare

Got it!  "Don't mess with it if you don't know what it is".  Trying to squeeze the last bit of performance out of something you don't understand is a doomed exploration indeed.

EMT-83

The wire sounds like like a classic "tiger tail" which simply adds the other half of a dipole to the existing antenna. You're not modifying anything, just making the antenna more efficient.

Likewise, using an external antenna doesn't change the specifications of a hand-held radio. It's still a type-accepted five watt radio, with a more efficient antenna. Adding an amplifier is obviously a different story.

CAP9907

Quote from: Falling Hare on February 06, 2019, 07:36:46 pm
I have started working in communications, which is a totally new and interesting field for me.  The problem is that I have zilch knowledge of radio/communications hardware or even basic electronics.  Have been using the old EF Johnson 5112 (version 4) handheld to get experience in voice communications on local Wing nets.

The other day a 'ham' showed me how to attach a home-made antenna to the hand-held that almost doubled the performance & range.  It is simply a wire about 18" long attached to a washer and inserted in the antenna well and then screwing the whip back into it's fitting.  It works great but looks really funky; and I am while I am careful attaching it into the fitting I am concerned that it may be damaging the equipment in some way.

My questions are:

-Is there an aftermarket longer whip antenna that would work just as well and replace the standard 8 ½" whip antenna.  Have tried a Baofeng NA-771 whip which fitted nicely but simply did not work.  Can anyone recommend specific brands, brand numbers, etc.? (links appreciated).

-Would love to use this in my car (it gets cold up here in the winter) so could anyone recommend specific magnetic roof antenna assemblies that would fit the EFJ 5112 (ver.4)?  Complete out-of-the box assemblies would probably be best for me since you have probably forgotten more about electronics than I will ever know. (Again, links appreciated).

The improved performance of the field expedient wire saves me having to drive 30 miles in to use the squadron base station when I have to get on the nets; would love something that looks more normal but gives me the improved range.


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SarDragon

Quote from: EMT-83 on February 07, 2019, 02:01:10 am
The wire sounds like like a classic "tiger tail" which simply adds the other half of a dipole to the existing antenna. You're not modifying anything, just making the antenna more efficient.

Likewise, using an external antenna doesn't change the specifications of a hand-held radio. It's still a type-accepted five watt radio, with a more efficient antenna. Adding an amplifier is obviously a different story.

Please (re)read the quote in my last post. Adding the antenna doesn't change the radio specs, it changes the usage, and the specs needed for that usage.
Dave Bowles
Maj, CAP
AT1, USN Retired
50 Year Member
Mitchell Award (unnumbered)
C/WO, CAP, Ret

Briank

Sounds like you should go get your ham tech license, an entry level ham radio, and join some ham radio nets!  Experiment there where it's encouraged.  That will help you gain radio knowledge without breaking any licensing rules.

Lebovic

I am also just learning about communications and know very little about it. Since I am just learning about using the radio pro words and way of speaking, and after learning the expense of buying my own equipment (could be thousands of dollars), I decided on a free way of practicing with some friends by starting our own digital channel on the zello app on a smart phone. This allows us to practice regularly with each other with no charge. We were thinking of downloading sample messages and practicing to send them over the radio. Let me know if you have any other good ideas. You can start your own channel, join other channels, or you are welcome to join ours, Federal Comm Practice. Whatever you choose, have fun, and good luck.

Adam B

Quote from: Lebovic on February 27, 2019, 02:36:43 am
...I am just learning about using the radio pro words and way of speaking, and after learning the expense of buying my own equipment (could be thousands of dollars)...


If you're talking about CAP comm specifically, yes. NTIA approved radios for CAP are very pricey. They need to meet strict testing criteria, and the testing and maintaining the tolerances needed for approval can be expensive. 

Ham radio, on the other hand, can be had quite cheaply. You get what you pay for, of course.
Baofeng, as mentioned by Eclipse, if possibly one of the best and worst things to happen to Ham radio. For $25, you can get a handheld Ham radio, with almost every feature you could want in an FM rig.   You can even listen to CAP frequencies!   The flip side is that the equipment is not very rugged and quality is very hit-or-miss, leading to a lot of potential frustration with people new to the hobby. Still, it's a viable option for very little cost.

Lastly, there's nothing stopping you from practicing on FRS radios, which are not only cheap and fairly reliable, but also very easy to find.

Honestly, I just love radio all around. Comm was my first CAP specialty track; I was an MRO and one of the wing's ACUT instructors (Abanaki 207, at the time). I played with CB radio as a teen, and I got my Ham radio license as an adult. I talked to someone 800 miles away in morse code using an old spoon as a straight-key. It's just the coolest hobby.   

I won't derail this any more, though. Feel free to PM if you want to chat radio stuffs.

K3CAN, out.



Adam