logansc

logansc

Well Known Member
I have two antennas hooked to my Garmin 530W (plus GPS, of course); one for VHF and one for the VOR system. Do I need a third antenna for the glideslope or do I only need a splitter or do I need nothing all additional to get the glideslope feature to work?

I currently have solid VOR azimuth performance including sensitivity switching, etc. but no glideslope.

I heard this a couple of different ways now, so thanks in advance for any insight provided...


Lee...
 
logansc said:
I have two antennas hooked to my Garmin 530W (plus GPS, of course); one for VHF and one for the VOR system. Do I need a third antenna for the glideslope or do I only need a splitter or do I need nothing all additional to get the glideslope feature to work?

I currently have solid VOR azimuth performance including sensitivity switching, etc. but no glideslope.

I heard this a couple of different ways now, so thanks in advance for any insight provided...


Lee...
Click to expand...

If it's the same as the 430W, you need to split the VOR antenna with this:

http://www.aircraftspruce.com/catalog/avpages/coupler507.php

One output to the VOR/LOC input, one to the G/S input.

You *could* put a dedicated G/S antenna on, but try splitting it first.
 
Thanks, Joe (RV7A Flyer). Confirms my suspicions. I actually had a splitter sitting around so I installed it this afternoon. I'll test fly tomorrow...

I appreciate the information...


Lee...
 
Lee,

Hopefully you used a diplexer not just a splitter.

The diplexer actually has filters in it to separate the two frequency ranges. A splitter just ties em both in parallel.

The splitter might work but it will have at least a 3db loss of signal. The diplexer does not split the signal, it separates it into two distinct ranges.
 
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Thanks Bryan; yes I believe I used the right part. Didn't get to fly it on a checkout flight today. Got some IFR practice in with a friend in his Piper Archer II and then another friend flew his RV-8 for the first time, so I flew chase on that effort (not very well, though!). I'll check it out tomorrow.

I used a RAMI AV-570 Diplexer Coupler. It is supposed to be specifically designed to provide signals to both nav and glide slope functions on 108-118 and 328-335 MHz, respectively.

Thanks for the advice, guys...


Lee...
 
thread hijack warning....

As I'm smack in the middle of wiring, the splitter question piqued my interest. My setup is a little different in that I have a single cat whisker Nav antenna feeding an SL 30 and a GTN 650. Both boxes have only a single nav input as both have an internal diplexer to split the VOR and GS signals.

I just looked and I have a RAMI 507 diplexer that I bought probably a couple years ago when my "planned" panel was 430 and an SL 40. Based upon the previous posts do I need to ditch the diplexer in favour of a straight splitter?
 
Brantel said:
Hopefully you used a diplexer not just a splitter.

The diplexer actually has filters in it to separate the two frequency ranges. A splitter just ties em both in parallel.
Click to expand...

Actually the 430 and 530 installation manuals call for a splitter.

Todd, you most definatately need a splitter and not a diplexer.
 
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Okay, now I'm a little confused. Just got back from flight testing my new Diplexer and it seemed to work just fine. If I should have used a splitter instead, it was not apparent. My 530 picked up the localizer and the glideslope just where I expected and both were stable and steady throughout.

Flew the ILS to Rnwy 23 at KRBW giving my whole system a pretty good workout: Had my TruTrak Pilot II fly azimuth while I controlled pitch/power/glideslope. Then I hand flew the GPS LPV approach to Rnwy 05 at KJYL with similar results. Hard to tell any difference between the ILS and the GPS LPV approaches. I had not flown either before; I have a lot more to go before I get really comfortable with either, but these are really sweet systems as everyone who uses them regularly knows. I was very pleased with the TruTrak btw, even though it doesn't have GPS steering/vertical steering.

If TruTrak will ever come out with their Gemini AP880, I'll be a happy camper---that is, if E-Mag will ever come out with their six-cylinder P-Mag too.

Sheesh!


Lee...
 
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Auburntsts said:
As I'm smack in the middle of wiring, the splitter question piqued my interest. My setup is a little different in that I have a single cat whisker Nav antenna feeding an SL 30 and a GTN 650. Both boxes have only a single nav input as both have an internal diplexer to split the VOR and GS signals.

I just looked and I have a RAMI 507 diplexer that I bought probably a couple years ago when my "planned" panel was 430 and an SL 40. Based upon the previous posts do I need to ditch the diplexer in favour of a straight splitter?
Click to expand...

The GTN series and the SL30 have built in diplexers so you want to use a "splitter" with them if you are only using one VOR/LOC/GS antenna to feed both of them. You will experience about a 3db signal loss from the splitter. The only way to eliminate the loss is to add a second antenna.
 
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logansc said:
Okay, now I'm a little confused. Just got back from flight testing my new Diplexer and it seemed to work just fine. If I should have used a splitter instead, it was not apparent. My 530 picked up the localizer and the glideslope just where I expected and both were stable and steady throughout.

Lee...
Click to expand...

Nope...you did it in a way that optimizes the signal and works very well. The confusion is due to the fact that some boxes have built in diplexers and some don't. The same advice does not work in all cases.

The diplexer actually has filters in it to separate the two frequency ranges. A splitter just ties em both in parallel.

A simple splitter might work but it will have at least a 3db loss of signal. The diplexer does not split the signal, it separates it into two distinct ranges. The diplexer is the optimum solution in your case.
 
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Walt said:
Actually the 430 and 530 installation manuals call for a splitter.

Todd, you most definatately need a splitter and not a diplexer.
Click to expand...

In the case of two boxes with built in diplexers such as the SL30 and the GTN series such as the setup Todd has, I would agree a basic splitter is all that is needed to share a common VOR/LOC/GS antenna between the two.

But for the setup that Lee has, a Diplexer is needed for best results.

Straight from the 430W manual (I don't have a 530W manual but I am assuming it is the same in this regard): "The GNS430W has a separate VOR/LOC and Glideslope inputs requiring some installations to use a standard external diplexer or triplexer."
 
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And also from the 430W manual:

Glideslope Antenna Shall meet TSO C34( ). Broad band, 50 Ω, horizontally polarized with coaxial cable or low-loss splitter used with the VOR/LOC antenna (GNS 430W Only)

I agree that using a diplexer is a better device for splitting the signal off for the GS input, perhaps this that is what Garmin meant when they say "low loss" because in other parts of the manual they use the term diplexer. Both will work but you'll have more signal strength with the diplexer.
 
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