Cherokee 180 with GNS 650 glide slope

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bobsk8
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Cherokee 180 with GNS 650 glide slope

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I don't know whether or not I missed some documentation, but flying an ILS in the 180, I can't get the top CDI to display any vertical info when I put the GTN 650 in CDI LOC mode. I see the bottom Nav radio has the ILS freq and I get the Loc on the single needle, but the top doesn't give me the vertical deviation. Am I doing something wrong.
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Nick - A2A
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Re: Cherokee 180 with GNS 650 glide slope

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Afraid I'm not familiar with the GTN units, but it's worth bearing in mind that not all ILS's have a glideslope available; sometimes it's just a localiser. Which approach were you flying?

In any case, the bottom nav radio (NAV2) can't be used to fly a precision ILS approach (one with a glideslope) in the Cherokee because it's not linked to an OBI gauge with a glideslope needle. For these precision ILS approaches, you need to tune the ILS NAV frequency into NAV1 which in your case is the GTN 650.

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Nick
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bobsk8
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Re: Cherokee 180 with GNS 650 glide slope

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Nick M wrote:Afraid I'm not familiar with the GTN units, but it's worth bearing in mind that not all ILS's have a glideslope available; sometimes it's just a localiser. Which approach were you flying?

In any case, the bottom nav radio (NAV2) can't be used to fly a precision ILS approach (one with a glideslope) in the Cherokee because it's not linked to an OBI gauge with a glideslope needle. For these precision ILS approaches, you need to tune the ILS NAV frequency into NAV1 which in your case is the GTN 650.

Cheers,
Nick
I tried with several ILS's that I use all the time. The problem is when I set the LOC frequency in the GTN, it adjust the freq in Nav 2. and the lower indicator , works showing the LOC course. The only time the upper OBI gauge indicates anything is when I switch the GTN 650 to GPS instead of LOC, then the upper OBI indicates the correctly. It's as if the upper indicator does not work at all for LOC/GS. Maybe this is a GTN issue, but I thought that I read somewhere, that the GS doesn't work in the Cherokee 180.
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Nick - A2A
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Re: Cherokee 180 with GNS 650 glide slope

Post by Nick - A2A »

As far as I'm aware, the GTN 650 config in the Cherokee should work fine with ILS glideslopes provided you've set the GTN CDI mode to VLOC as you mentioned. Maybe some GTN 650 users will be able to chime in here. It'll probably help if you post a couple of screenshots showing the issue you're describing.

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Nick
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bobsk8
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Re: Cherokee 180 with GNS 650 glide slope

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Nick M wrote:As far as I'm aware, the GTN 650 config in the Cherokee should work fine with ILS glideslopes provided you've set the GTN CDI mode to VLOC as you mentioned. Maybe some GTN 650 users will be able to chime in here. It'll probably help if you post a couple of screenshots showing the issue you're describing.

Thanks,
Nick
I think I found out the problem. I installed the default GPS in the panel, using the A2A config, and started the Cherokee, and the Nav com #1 is dead, it will not turn on and all. I guess I will have to reinstall the Cherokee.
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Re: Cherokee 180 with GNS 650 glide slope

Post by Nick - A2A »

Sounds like something could be a little funky with the installation, but have you checked the fuse for "NAVCOM 1" just under the pitot heat switch?

Nick
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bobsk8
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Re: Cherokee 180 with GNS 650 glide slope

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Nick M wrote:Sounds like something could be a little funky with the installation, but have you checked the fuse for "NAVCOM 1" just under the pitot heat switch?

Nick
The sound you may here is me smacking myself in the head... I am a retired teacher of electronics, and you would think that the first thing I would look for is a blown fuse........ :oops:

Thanks for your help, I really appreciate it...

Bob
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Re: Cherokee 180 with GNS 650 glide slope

Post by Nick - A2A »

Hey - you're welcome. Glad it was an easy fix with no reinstallation required. :) If it's any consolation, it seems the navcom 1 fuse implementation is a little dodgy when the GTN unit is installed, as rather than removing power to the entire unit, it appears to just remove its ability to tune navaids.

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Re: Cherokee 180 with GNS 650 glide slope

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Nick M wrote:Hey - you're welcome. Glad it was an easy fix with no reinstallation required. :) If it's any consolation, it seems the navcom 1 fuse implementation is a little dodgy when the GTN unit is installed, as rather than removing power to the entire unit, it appears to just remove its ability to tune navaids.

Nick
I found the problem. After I fixed the fuse, the top radio worked, but I was still controlling the bottom radio when I switched the Nav frequency in the GTN 650. Therefore I could not get a G/S indication because the CDI for the bottom Nav radio has no glide slope indicator. Then I decided to look on the GTN configurator, and found out that there was a setting in the config to determine which radio the GTN was controlling. It was set to Nav Com 2. So whatever frequency was set on Nav 1 when installing the GTN 650, it stayed there forever and of course the CDI never moved.I changed it to Nav Com 1 in the GTN configurator , and now everything is working perfectly.
Last edited by bobsk8 on 24 Jul 2016, 08:43, edited 3 times in total.
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Nick - A2A
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Re: Cherokee 180 with GNS 650 glide slope

Post by Nick - A2A »

Okay - just out of interest, what happens if you try to tune the NAV1 frequency using the shift 6 'quick radios' panel rather than the GTN 650?

Nick
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bobsk8
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Re: Cherokee 180 with GNS 650 glide slope

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Nick M wrote:Okay - just out of interest, what happens if you try to tune the NAV1 frequency using the shift 6 'quick radios' panel rather than the GTN 650?

Nick
See above solution I found.
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Re: Cherokee 180 with GNS 650 glide slope

Post by Nick - A2A »

Aha - good to hear it's all sorted.

Nick
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