From my current reading: The older 360 channel radios use 50 kHz spacing for the channels (122.75, 122.80, etc). The new 720 channel radios use 25 kHz spacing (122.750, 122.775, 122.800). The radios are designed to operate on the selected frequency +/- a given tolerance. The tolerance is large enough to allow for temperature and manufacturing variations but narrow enough to prevent interference with the adjacent channels. The 360 channel units had 50 kHz to play with but the new ones only have 25 kHz. Therefore, an older radio could be operating to its 50 kHz specs, but still interfere with an adjacent 25 kHz channel if it was close to the upper or lower edge of the tolerance.
Some folks have discovered that they can receive some of the newer 25 kHz channels by tuning to one of the adjacent 50 kHz channels. If the radio's frequency is off enough to do this, it's probably off enough to spill over when transmitting.
I've read that some of the 360 channel radios can be retro-fitted to the tighter frequency limits and will still be allowed. I saw a table in a aviation paper/magazine that listed which radios could be retro-fitted or already met the tighter tolerances. As I recall, the COM11 and COM11A could not be updated, but that the COM11B could be upgraded or already met the new specs. I'll try to find the source and post it.
Narco: ...and a third refused to even look at it.
Dittos here. My Narco VOR is shot and I've had two say they wouldn't even mess with it and a third say it'd cost more to fix than it's worth, especially since it's a Narco. Sigh.....
I believe that a couple of years ago, Narco put out a bulletin to avionics repair shops indicating that the repair shops were no longer authorized to repair Narco radios. All Narco equipment was to be shipped to Narco for repairs.
If this policy is still in effect, that's certainly adequate reason to completely avoid Narco, in my opinion!
I've been able to get plastic gears for my NARCO COM11A, ADF 140 AND COM120 from the Radio Shop in Worcester, MA. No parts were available from them or the factory for the glide slope flag display of the NAV12.
Narco subsequently changed this policy and allow field repairs by "authorized" depots.
Maybe so, but they've still got a stranglehold on their parts. I needed a plastic gear for the tuning knob on my COM11B, and NARCO told both the radio shop and me that they would not sell this piece.
I've got original 1976 King Silver Crown in my Tiger but wondering how I was doing between VOR's and for my airports only approach, an NDB/DME, put in a Narco DME a couple years ago. My Kings took a bit of work to put them in good shape after I bought the plane almost 7 years ago and still need OBS adjustments often but are pretty reliable and easily fixed by any avionics shop if they do act up. I don't figure on upgrading them until a whole new concept of avionics comes into being. But your messages have me a bit worried about my Narco DME because unlike the Kings, I think it has to go back to the factory for repairs.
I had to send my Narco DME to the factory for a replacement of the tenths digit about 6 months ago. Response from the factory was fast, but it sure was expensive. Saturday, when we flew (VFR fortunately) the tens digit is out. Now, I also am in the dilemma. Do I repair it again or junk it?
I contacted Narco and they now allow certain dealers to perform repairs. The nearest to me is Fresno (160 miles). The King equipment is expensive! It can be serviced in Bakersfield (50 miles) but I still must send it out. What was the problem with sending Narco radios back to the factory? Where they too expensive, poor quality, slow? Seems like a fairly good idea to someone without a local avionics shop. If I had King and it was broken I would consider sending it to the King factory. What about Terra? Has anyone tried them? A new Terra is cheaper than a used KX-155, has a three year warranty, is smaller, and lighter too!
Narco did indeed rescind it's "send it to the factory" order. However, trying to find a shop that has started repairing Narco gear again can be like finding a needle in a haystack. I guess the avionics places are thinking "once burned, twice shy," to continue the cliches.
You will be sorry if you buy a Narco radio. Factory service is slow, expensive , and does not always fix the problem. Take some advice from me, buy the King , skip lunch for a year, and your Nav/Com worries will be over.
I just had a similar experience as far as older Narco gear goes. Two avionics shops said they would send my ADF-141 directly to Narco rather than repair it in house, and a third refused to even look at it. In addition, they didn't give especially glowing reviews of the factory service on out-of-production radios. As you can guess, I'm not exactly champing at the bit to spend $500 to fix a dead loop amp (recommendations, anyone?) by mail order. My vote is for King next time around.
All together now - "NARCO: Not A Radio Company"
The comments about servicing Narco gear are on target. A couple/few years ago, Narco, in their infinite wisdom [not] decided that the factory ought to do all the service on their radios. They won't supply parts or manuals to nobody, so shops are legally bound to say they can't work on this stuff since they can't get current documentation.
My Tiger came from the factory with an assortment of Narco gear. A King DME was added, and when I decided to upgrade some stuff about 5 years ago (mostly because of problems with some of the Narco gear), I went with a KX155 and KMA24. The King stuff has been trouble-free (knock on aluminum).
If you can afford it, I'd recommend King. Even used King stuff would probably be better than Narco. Oh, and the PS Engineering PM1000 intercom has been trouble-free and has worked quite well also.
My only word of advice- do anything you can (sell firstborn child, etc) to avoid putting Narco products into that airplane. I have a very nice Tiger and have had nothing but extreme grief dealing with Narco trying to solve some relatively simple problems. It has taken nearly a year (during which I couldn't fly IFR because of inadequate gear) and has been expensive. I wish I could say something better about their product support, but I can not. Get a KX155 (they are on sale now ) and be done with it. Keep those needles crossed-- Jackson
What was the problem with sending Narco radios back to the factory? Where they too expensive, poor quality, slow? Seems like a fairly good idea to someone without a local avionics shop.
Yes to all of the above. My IDME-891 is going back for the fifth time, two times for no DME, three times for no GS indication (but a good flag). My ADF went there three times. The audio panel and Mark 12D have been once. The Mark 12D went there in an attempt to fix the no GS indication problem, otherwise working perfectly (which we are now pretty sure is in the IDME-891, which is going back again this week) and they claim it was dead when it got there with a shorted 16V. That cost me an extra $350. I am just short of the point of ripping out those three-year-old radios and putting in either King or Terra. It's that frustrating not to be able to depend on your radios for IFR trips.
I'm gonna buy a boat!
I dunno Fraser. I have both and I think the boat cost me more. Plus every time I take it out I break something, on it or on myself!
I have heard varying reports on Terra radios. Universally, people say to avoid the old mechanical ones. However, the new all-electronic ones seem to be much better.
I had one of the first ones (Terra's) with the little tuning wheels. I liked it except when it was bumpy and tuning was exceedingly difficult if not impossible. As you live in Albuquerque, (My favorite place on the continent), I'd suggest you go for it.
Terra knobs too small to tune in turbulence, otherwise no experience.
Get a Terra stack. You can get a solid state COM/NAV with glideslope (and warranty) for $2400. The nav and com will fit in a single slot in the stack, and the VOR/GS head fits in a standard hole. I like the digital readout of the VOR/GS.
Add a $300 Terra MB somewhere (or add one to your audio panel...) and you're set!