As I have written about previously, I purchased a Zlin 142 that had been used previously as a primary trainer. Airframe- and engine-wise it is a sound plane and with an ELA1 maintenance programme the projected costs are not that bad. It, however, lacks any avionics except for its ancient (but acceptably working) LUN 760-channel COM radio, i.e. there is no transponder at all. I would like to equip the plane for VFR touring, the kind of flying I will be doing in the foreseable future. I have considered adding the following pieces of equipment:
- an 8.33 COM radio
The radio permit is valid until August 2017, so I may wait for one more year, but after that I will have to install a new radio. I am looking for either a Trig TY91 radio (suggested here on the forum and by a reputable Hungarian avionics shop) or some cheap German device (most likely a Dittel KRT-2). I know that the Trig is much better, but the price difference would pay for quite a few hours up high.
There is no audio panel, the LUN radio handles the two-place intercom and the new radio will have to do the same. I would like to keep the LUN radio, since it is basically unsellable and it would be nice to have an emergency comm option. The reputable avionics shop says that it may not be possible to keep both radios, partly due to regulations, partly due to the need of an audio panel. What do you think about this? Is it not possible to have a 8.33 kHz radio with a 25 kHz one as a backup? Also, does anyone knows if it is possible to connect both radios to the same headset connectors? Of course only one would be powered at a time.
- a transponder
I may be able to get a cheap mode C transponder, but I feel that it would be a waste of money since mode S requirements are on the horizon and are the reality in some airspaces where I would likely fly. Here the question would also be whether to install a Trig TT21 or the Dittel KTX2 or to find some cheap KT-76(A) and have it installed, and later sell it in the US when mode S will be required here?
Btw, what is the fair market price of a used KT-76(A) with EASA paperwork?
- a 121.5 + 406 MHz ELT
I got a quote from the above-mentioned avionics shop for a Kannad ELT. I will most likely not do this, but rather get a GPS-equipped PLB, for the reasons discussed in that thread. Is the ACR PLB-375+ any good for Europe?
I would welcome any suggestions or insights from you. I will post photos of my actual panel when I can make a few quality ones, but this is fairly close to mine.
The Trig TY91 has standby frequency monitoring, a good built-in intercom and an auxiliary audio input. So you may not feel the need to keep the old radio as a standby.
You could easily patch a hand-held radio into the aux input as an emergency stand-by, or use it to patch in the audio output from a GPS (or listen to music if you feel the need)
There’s still a ready market in the US for KT76 and 76A despite being 30-40 years old, they seem to keep on working. I expect them to sell in the range $400-800 depending on condition, model etc.
JnsV wrote:
I am looking for either a Trig TY91 radio (suggested here on the forum and by a reputable Hungarian avionics shop) or some cheap German device (most likely a Dittel KRT-2). I know that the Trig is much better, but the price difference would pay for quite a few hours up high.
I would also recommend to choose a Trig, and not go with one of the German brands. They do have a quite high number of issues from my experiance. I haven’t had quality issues other then a two early trig TT-31, which where solved very quickly (next day). With this other brands your waiting for weeks.
JnsV wrote:
The reputable avionics shop says that it may not be possible to keep both radios, partly due to regulations, partly due to the need of an audio panel. What do you think about this? Is it not possible to have a 8.33 kHz radio with a 25 kHz one as a backup? Also, does anyone knows if it is possible to connect both radios to the same headset connectors?
Yes it would be possible to use both radio’s, even at the same time without audio panel. It might need some isolation resistors in the audio output, and switching of the PTT only. And each radio would require it’s own antenna. The 25 kHz backup is different in every country. You would spend quite some time for a dual installation. I would recommend to go only with the TY-91.
JnsV wrote:
Here the question would also be whether to install a Trig TT21 or the Dittel KTX2 or to find some cheap KT-76(A) and have it installed, and later sell it in the US when mode S will be required here?
Btw, what is the fair market price of a used KT-76(A) with EASA paperwork?
Again, I would spend the money on a Trig, it’s better equipment, and if you need support they will deliver support fast. Having both the TY-91 and TT-21 might save you some, on equipment and/or labour.
JnsV wrote:
I got a quote from the above-mentioned avionics shop for a Kannad ELT. I will most likely not do this, but rather get a GPS-equipped PLB
It is important to understand the difference. A PLB will be quite useless at an unexpected crash. Kannad is an economical ELT which I also would recommend. Yet they also have some issues (quite rare though). I think that a PLB and ELT supplement eachother, they are IMHO no replacement for eachother.
Jesse wrote:
They do have a quite high number of issues from my experiance
To get radio and transponder working together without interference and cancelling of frequencies seems more like voodoo magic than anything else. It seems to me the quality of the products are not the issues, but rather the know how of how to install these things in one particular airframe with one particular set of other instruments. Nevertheless, I have also heard only positive things about Trig transponders. The one with removable head is also very easy to install.
LeSving wrote:
To get radio and transponder working together without interference and cancelling of frequencies seems more like voodoo magic than anything else. It seems to me the quality of the products are not the issues, but rather the know how of how to install these things in one particular airframe with one particular set of other instruments.
I don’t agree here. Proper RF measures are always recommended and done by most shops. These radio’s are often installed in “simple aircraft”. A small aircraft loaded with avionics and a small space for all antenna’s can be difficult.
There are also some installers who don’t read and don’t seem to have general knowledge on RF. Incorrect installation of antenna’s and feeder systems are quite common, especially on sensitive systems like stormscopes and ADF, and on very high frequencies which are more sensitive to the nature of the high frequencies used. Think of active traffic systems.
For example, last week I had again a Germany build radio which didn’t want to transmit. There are quality issues around, with several manufactures. None of them have a 0% failure rate. The main difference is how they solve problems, and Trig is very good at that. That combined with a low failure rate makes them the currently the best manufacturer IMHO.
Another example is another German radio in a Glider which I had in for troubleshooting. Found 2 year old transmitter didn’t transmit. Checked and measured coax cables and antenna’s, found ok. Had the unit repaired by the manufacturer (shop repairs not allowed). Repair was almost as expensive as a new unit. Received the unit back with repaired forms, having the unit in my hands for 10 seconds I saw some hardware was missing.
So this unit failed fairly sudden, repair price was high, repair took six weeks, after repair not all hardware was reinstalled. This is not the kind of quality I would like to recommend to my customer, nor in general.
If that Hungarian shop has similair experiances it is logical to me that they would advise Trig equipment, for this type of installation. In the cases where a Trig failed, Trig quickly supplied an exchange unit, once under warranty, other unit was out of warranty, but at very fair price (about 1/4th of the German manufacturer).
I think I would agree with Jessie’s comments, I have installed trig transponders in all my working aircraft and three years on they are faultless.
The trig comms radios installed in customers powered aircraft are also very reliable, however the trig power consumption is a bit higher than some of the German radios and this might become the deciding issue for those looking to fit a comms radio to a glider that is flown by pilots at the serious end of the sport.
Dear JnsV, you might consider the PAR200A, it has the remote mounted 8.33 KHz Trig TY91L that is control by the audio panel itself. This would give you radio switching means if you keep your LUN radio. The intercom is hi-fi stereo with Bluetooth for music streaming and phone calls.
I have been demoing it this week at AERO-Friedrichshafen and it has been widely received.
Mark Scheuer
PS Engineering
Thanks for all the suggestions, folks.
Jesse wrote:
Another example is another German radio in a Glider which I had in for troubleshooting. Found 2 year old transmitter didn’t transmit. Checked and measured coax cables and antenna’s, found ok. Had the unit repaired by the manufacturer (shop repairs not allowed). Repair was almost as expensive as a new unit. Received the unit back with repaired forms, having the unit in my hands for 10 seconds I saw some hardware was missing.
So this unit failed fairly sudden, repair price was high, repair took six weeks, after repair not all hardware was reinstalled. This is not the kind of quality I would like to recommend to my customer, nor in general.
This is the kind of problem that I would fear the most. I have decided not to try to save money on the short term by going towards any of the German brands; I will stay with Trig. I may not have the budget this year to do everything at all and leaning towards saving money by installing a used Mode C transponder (most likely a KT-76A). If I read the AIPs correctly, for a VFR aircraft it would only be a major limiting factor in Belgium and the Netherlands, and to some extent in Germany. Am I correct? I also think that it would be relatively easy to upgrade it in the future to a TT-31 or similar, wouldn’t?
Mark wrote:
Dear JnsV, you might consider the PAR200A, it has the remote mounted 8.33 KHz Trig TY91L that is control by the audio panel itself. This would give you radio switching means if you keep your LUN radio. The intercom is hi-fi stereo with Bluetooth for music streaming and phone calls.
It seems to be a very nice unit. I may contact you with some further enquiries.
So based on the above input I have decided to do the S-mode transponder now and the radio next year. The panel is very accessible, so there is very little extra work involved this way.
Jesse wrote:
Yes it would be possible to use both radio’s, even at the same time without audio panel. It might need some isolation resistors in the audio output, and switching of the PTT only.
And each radio would require it’s own antenna.
This complicates the installation quite a bit. Is it not possible to do it from the same antenna?
The 25 kHz backup is different in every country. You would spend quite some time for a dual installation. I would recommend to go only with the TY-91.
I would still not be happy with a single COM radio installation on the long term. I have had 4 issues so far in my short aviation career where one of the radios became unusable. (Btw, in three of the cases the culprits were GNS-430 units.)
Is it not possible to do it from the same antenna?
Not possible, unless you can somehow guarantee that only one of the two radios will transmit at any one time. And even then it would be messy. Having two separate radios is priceless, because a lot of problems are caused by a bad antenna or the connection to it.
I have heard a number of very good reports from Jesse’s customers.
