Any Garmin 175 GPS pireps? Install time?

[Immelman]

I've got a big old hole in my panel from a KLN-88 LORAN, now removed except for its tray and antenna. Dual King nav/comm, each with glideslope, and a king HSI. The LORAN was setup with a switch between loran and VOR/LOC.

I am thinking now is finally the time to get GPS approach capability without breaking the bank. It appears that the Garmin 175 is compatible with my King HSI, and so I'd be looking to remove the LORAN tray, antenna, and HSI switch and replacing with a similar setup with the Garmin. I also have an STEC-50 autopilot that can be driven in nav or approach mode from the HSI. I have no interest in more capability like GPS steering.

What say the community? Any hidden costs or gotchas in this approach?

 

 

[David Lloyd]

I recently had a 375 installed along with a PAR200B audio panel/com.  It works fine with my Stec 60-2 with some limitations.  Going over any waypoint may involve some zig zagging while recapturing the course.  GPSS would eliminate that.  Are you going to put in another switch to select between VOR/LOC and GPS?

One possible hidden cost, older radios such as the KX155 and 165 may cause problems with the GPS.  I was lucky in that a notch filter solved the problem.  The radio shop said sometimes that works, sometimes not.  They used the word lucky.

I had old transponder, ADF, audio panel, GPS and 10 pounds of old wiring removed.  Some panel work and moving stuff around, one old nav indicator was junk and replaced.  Had an unforeseen problem with my HSI, and replaced that with a spare.  So, a bunch of labor, about 75 hours.  A fairly simple install with minimal rewiring, expect about 30 hours labor.

[Immelman]

That's a nice, clean panel! Thanks for the heads up.

Yes I would like to be able to switch the HSI to be driven by either the #1 nav or the new GPS. Basically the same setup as the LORAN had. This is something I am curious about in terms of expense and complexity. I would not want to lose the ability to do an ILS or LOC approach using the HSI.

Can you elaborate on the "notch filter"? Is the concern that the mere presense of the 155/165 cause enough interference to mess with the GPS? That would be sad indeed.

 

[David Lloyd]

I did not have such a switch with annunciator installed.  Expect $500-750.

The problem I had with my 165 was one some frequencies (123.xx, 127.xx and 132.xx) when the mic was keyed the GPS would loose its signal lock.  It would quickly lock back on but not comfort inspiring.  Might have those frequencies wrong but you get the idea.  The 155/165 were great radios but designed years before GPS was a consideration.

[Niko182]

I have a 375. It works as advertized and does an awesome job for a very small amount of money when you consider how expensive avionics are. I would personally just connect the 175 direct into the HSI and have a second CDI for a localizer woth glideslope. Once you get rnav, the reality is that Rnav approaches are so simple and thats really all you stick to.

[carusoam]

There were a couple of threads when first announced...

https://mooneyspace.com/search/?q="Garmin 175 gps"&updated_after=any&sortby=relevancy&search_and_or=or

-a-

[Warren]

You can get the 175 and a KX radio to feed the same indicator.  Use an RS-08 switch ( I am sure there are other options as well) to select between Nav/com or GPS being fed to the indicator.  The RS-08 is a relatively simple install as it is only one connector.  You will likely be able to reuse the switch used for the Loran and KX as the same signals will be coming from the GPS 175 to feed the indicator.

Edited July 14, 2020 by Warren

[59Moonster]

On 7/13/2020 at 4:54 PM, David Lloyd said:

One possible hidden cost, older radios such as the KX155 and 165 may cause problems with the GPS.

 

Any examples or know what some problems are? I have the 375 and a 155. I haven't noticed anything strange in the 40+ hours I've flown it since install. Also my shop didn't say anything so this is the first I've heard of it. 

[David Lloyd]

During installation your shop should have checked interference with other equipment, part of G's install checklist.  Some do, some don't. Ask your radio shop if they have run into this problem.  Example, yes read a couple posts down from where you quoted.

[wiguy]

 I just put $$ down today for a GPS-175 & 2 G5’s. My current radios are ok, we shall see, and evaluate. My directional gyro has never been optimal, I like that attitude G5 too.

[Niko182]

Just now, wiguy said:

 I just put $$ down today for a GPS-175 & 2 G5’s. My current radios are ok, we shall see, and evaluate. My directional gyro has never been optimal, I like that attitude G5 too.

If your current radios are only ok, spend the extra cash and get the gnc355, and get rid of one radio.

[romeotango]

Are marker beacon receivers considered passe these days?

[David Lloyd]

Yep.

[Andy95W]

9 hours ago, wiguy said:

 I just put $$ down today for a GPS-175 & 2 G5’s. My current radios are ok, we shall see, and evaluate. My directional gyro has never been optimal, I like that attitude G5 too.

I just did the same.  Installation is going very well, most straightforward avionics installation I've ever done.

Are you doing the work yourself/with an A&P/IA?  If not, then the recommendation to get the GNC-355 GPS/COM is very good.

[Immelman]

What kind of quotes did you guys get? Stepping back and thinking about this I too wonder if the 175 is the right choice vs the one with a comm builtin and getting rid of the #1 nav/comm (KX165) and simplifying the installation.

Edited July 30, 2020 by Immelman

[Andy95W]

I'm doing it myself, so I had to get the 175.  The others are only available for installation through a Garmin dealer.

I'm so slow I'm not sure you can glean a good estimate of hours from me.  I think for a competent avionics shop, 8-12 hours for the 175 installation would be a good number, and 30-40 hours for the dual G5/175 installation that I'm doing with interface to an STEC autopilot.  

My installation will probably end up being on the order of 70-80 hours.  If I were to do another, it would probably be 40-50.  But again, I'm slow.

[tmo]

The interference from VHF transmitting equipment, on specific frequencies e.g. 121.150 MHz 121.175MHz 121.200MHz 131.250MHz 131.275MHz 131.300MHz and some others as described around page 143 of AC_20-138D

[Skates97]

10 hours ago, Andy95W said:

I'm doing it myself, so I had to get the 175.  The others are only available for installation through a Garmin dealer.

I'm so slow I'm not sure you can glean a good estimate of hours from me.  I think for a competent avionics shop, 8-12 hours for the 175 installation would be a good number, and 30-40 hours for the dual G5/175 installation that I'm doing with interface to an STEC autopilot.  

My installation will probably end up being on the order of 70-80 hours.  If I were to do another, it would probably be 40-50.  But again, I'm slow.

Are you sure? I bought a GNC 355 and it was shipped to my AP/IA. Sitting on my shelf right now waiting to be installed at a future date.

[Andy95W]

I must be wrong about the GPS/COM version.  The GPS/ADSB version (375) is dealer only, so I just assumed.

Luckily I have a good COM 2, or I would've missed out!

[David Lloyd]

tmo, thanks for the reference.  Here's what it says;

21-1. Ground Test - GPS, GPS/SBAS, and GPS/GBAS. 21-1.1 Interference. a. The lack of interference from VHF radios should be demonstrated on the completed GNSS installation by tuning each VHF transmitter to the frequencies listed below and transmitting for a period of 30 seconds while observing the signal status of each satellite being received. Degradation of individually received satellite signals below a point where navigation is no longer possible is not acceptable and will require that additional isolation measures be taken. Re-evaluation of installed VHF transceiver performance is not necessary if the filter insertion loss is 2 dB or less. b. Evaluate the following VHF frequencies (25 kHz channels): 121.150 MHz 121.200 MHz 131.275 MHz 121.175 MHz 131.250 MHz 131.300 MHz c. For VHF radios with 8.33 kHz channel spacing, evaluate the following additional VHF frequencies: 121.185 MHz 121.190 MHz 130.285 MHz 131.290 MHz

The radio shop demonstrated this for me.  Brought up the page showing signal strength of all the satellites, set the first com frequency on the KX-165 and keyed the mic.  On a couple frequencies, one or two satellites lost their lock. The other seven or eight satellite reception was unaffected.  The shop said this was acceptable as long as the navigation was not impaired. And this was after the shop had spent some time moving antennas, and adding a filter.  My new PAR200B did not affect the GPS signal whatsoever.  Difference between old and new design.

 

[wiguy]

On 7/29/2020 at 11:10 AM, Niko182 said:

If your current radios are only ok, spend the extra cash and get the gnc355, and get rid of one radio.

 We had a serious GNC-355 discussion, I’m also getting the duel G-5’s. The budget is the reason. My best radio is a very late model kx-155, works fine. I know, some things make sense once the panel is laid bare. I’ll have to cross the radio failure bridge when I come to it.

  The work is being done by my maintenance & avionics shop, new 406 ELT too, along with annual.

Edited August 2, 2020 by wiguy