Can I save my Narco Antenna?

[paulbritton88]

I really like the look of my cool old Narco Nav antenna. However, my VOR reception stinks. I've tried two radios. The best I can get is 15 miles. I put in a new cable from the Nav/COM to the antenna, and rebuilt the balun inside the antenna using this diagram:

My Avionics guy says scrap it and hang one on the tail. I really don't want to do that. WIll a new Comant CI-158 fit if I machine out the top of the mast to accomodate it? Anyone try this already??

[GAHorn]

Your avionics guy is full of himself.
Antennas are simple and easy to maintain and repair.
They are not dark magic.
OHM OUT your narco for shorts...then look elsewhere
for your reception problem.

[blueldr]

I guess if you're going to file and fly IFR in the existing system you'll need that VOR, otherwise I'd get rid of it and go GPS which will give you azimuth and with true range, not slant range like a DME.
In view of the apparent upcoming demise of the VOR system, I don't believe I'd spend much money on getting it fixed.

I like to run on Mogas, too!

[Bruce Fenstermacher]

Your Narco antenna can and should be able to work like new. I did switch from the Narco antenna to one on the tail once. It's not as easy as you think. I wouldn't do it again unless I had a really good reason and just getting rid of the Narco antenna is not one of them.

[LBPilot82]

I recently refurbished my Narco antenna as well. I assume you have already done so, but be sure you thoroughly clean the "sockets" where the antenna ears enter the top of the mast. I cleaned my with a bead blaster as well as all the connections inside. Never had a problem with reception. You might consider some grease or something to prevent corrosion on the connection points. I love the look of that old thing!

[edbooth]

Your avionics guy is full of himself.
Antennas are simple and easy to maintain and repair.
They are not dark magic.
OHM OUT your narco for shorts...then look elsewhere
for your reception problem.

I agree with George, these antennas are all built the same no matter if they are fifty years old or just off the shelf. Clean connections, grounds and good lead wire is the key......I think the old ones are cool looking also. I just cleaned and painted mine.

[paulbritton88]

I recently refurbished my Narco antenna as well. I assume you have already done so, but be sure you thoroughly clean the "sockets" where the antenna ears enter the top of the mast. I cleaned my with a bead blaster as well as all the connections inside. Never had a problem with reception. You might consider some grease or something to prevent corrosion on the connection points. I love the look of that old thing!

Did you make a new balun or stick a "modern" one inside the top of the mast?

[LBPilot82]

No, I re-used all the old stuff. Just cleaned everything well, applied some corrosion proofing to the connectors, and shot a coat of paint. I used some light steel wool to clean up the antenna ears. I ended up hand painting the lettering with black over the white base (I must say.. it came out pretty nice!!)

[GAHorn]

Did you retain the original RCA connector..... or did you install a BNC ?
Have you checked it for shorts and continuity?
If it does not"ring out"....then I would suspect the element ferrules before the old balun,
and yet not be afraid to make
a new one from new materials.
Be careful using anti-corrosive.
Many are conductive and you don't want to affect the
impedance.

[paulbritton88]

New BNC connector. However, I think I need to make the balun longer. Everything I have read suggests the balun length should be the same as the dipole antenna length.

Here's the current plan:
Make a new balun, 26" long. It won't all fit inside the antenna mast, but so be it. New RG-400 shielded line from the balun to the back of the Nav Com.

I'll follow this set of directions:
http://www.aeroelectric.com/articles/BA ... ation.html


I wonder if, it needs to be grounded at the antenna base, or is the ground through the Nav/Com sufficent? I might just build it wtihout a ground, first and see how it works.

I stripped and painted it already.

[paulbritton88]

OK, The Nav/Com is back from the shop. Still bad reception.
I've changed the Balun, twice, using both of the above designs.
Tried two know good KX-170Bs and still have the same results:
Weak reception. Scratchy Voice/Indent. Wavering Course Indicator.

The COAX from the radio to the antenna shows good connectivity on the center wire and the shield.
The Nav/Com is good.

So,
The way I see it, my problem is in the rack/connector or the antenna.

The bullet shaped ferrules look to be insulated with a brass interior. I've cleaned them. Is there a chance the exterior sleeve is conducting?
I've been told to "ring out" the antenna.
Texas public school educated here..... Just how does one "ring out" an antenna?

[GAHorn]

Using a battery-powered "buzzer" or "bell" with leads...an electrician will "ring" out a device (check it for shorts, connectivity, continuity, etc.)

[paulbritton88]

So the answer is Yes.
It turns out that the KI-208 Course Indicator, my (ex) avionics guy (long story) sold me and installed was the culprit.
I ordered another C.I., installed it and voila!

I can pick up every VOR within 60 miles at pattern altitude.
Just in time. My student starts cross-country training this week.

Thanks for the help guys!

[GAHorn]

Sooooo....Moral of story- Original, Made in America, properly maintained is Provender!

Good Job! (and CONGRATULATIONS!)

[LBPilot82]

Paul, did you end up going with a 26" balun? If so, wouldn't the excess stick out the bottom and hit the headliner? It seems other sources recommend a 16" balun measured from the top of the loop to the point where the shields are connected at the base. From what I gather, the 16" dimension is derived from calculating 1/4 of the average wavelength used from 108.0-117.95mhz. My narco which appears to have the original balun (with some previous connector modifications) measures 17". I am making a new one and could easily duplicate my balun, but curiosity has got the best of me. Anyone else an expert in the matter??