Poor reception flying toward station.

[Carl Froehlich]

One key point not discussed. Antenna proximity to another antenna, unless inches away, how close will have not practical effect on reception. As the problem here is reception when both radios are in the receive mode, antenna separation is not the problem.

I’ve flown with two belly bent whip antennas on three RVs, spacing between 20” and 30”. Never a problem even when transmitting on one while receiving on the other. The caveat however is your experience will also be dependent on your choice of radios.

Curious - the only hard antenna problem I had was on the 90 degree connector I used for the GTN-650 BNC connector at the radio. The problem was found when ringing out the coax and wingtip antenna as a system. The problem was I left a small “spike” on the center connector to coax solder joint. When the protective cap was installed the spike shorted to ground. 20 seconds with a soldering iron and all was well. You’d think with more than 50 years of making antennas and coax runs I’d know better. This proves the point of always ringing out antenna systems with the right instruments.

Ground plane. Don’t get wrap around this dimension. There is no rule the ground plane must be a perfect circle. Just look at helicopter comm antennas mounted out on the tail boom. The antenna is looking for a counterpoise, not a ground plane. Again on a well instrumented antenna range you can measure the difference in radiation patterns between size and dimensions of counterpoise installs. But for our need this is in the grass.

Last recommendation - any chance you can swap out the 650 with someone else's radio?

Carl

[GalinHdz]

As I posted:

Originally Posted by GalinHdz

Did you physically remove, not just disconnect, the GTR200 antenna and do a test flight as Bob recommended? This will confirm/eliminate an antenna proximity issue before attempting something else.

Systematic troubleshooting, to fix anything, requires one step at a time.

[ksdflying]

Galin, Carl,
1. Yes I physically removed the antenna totally off the airplane. This action made the gtn 650xi radio Com-1 as the only Com and Com antenna.
No change.
2.Carl, no I have not had that opportunity yet of borrowing to swap out 650 units. Tomorrow (wednesday) I am supposed to have an appointment at a Garmin avionics shop. So we will see what they find out.

[ksdflying]

Originally Posted by JDA_BTR

A lot of good discussion about the xmit interlock. The original post was a receive problem and there is no interlock active on receive. I’m very curious if the problem moved to the other side when the antenna connections were switched. Is it the antenna or the radio? Does the problem clear entirely with antennas swapped?


Can the OP say what’s different now?

I was hoping the original poster would have replied too perhaps with a finding.
But as for me, 1. No the 1/3rd range issue of the gtn 650xi did NOT move any of the times I swapped antenna coax connections. 2. No the problem does NOT clear up with swapping antennas, ...furthermore when I totaly removed the 2nd Com, the gtr 200 out of its rack, pulled its breaker, AND removed its antenna from the plane, it did not change.

[GalinHdz]

Sounds like you have an issue with the GTN650. Either that or you have an exceptionally good GTR200 and a slightly below average GTN650.

[BobTurner]

I would have suggested removing the gtn antenna, entirely, and see if the GTR returns to its previous good performance. If no then likely its ‘front end’ was damaged by overload.

[ksdflying]

Originally Posted by BobTurner

I would have suggested removing the gtn antenna, entirely, and see if the GTR returns to its previous good performance. If no then likely its ‘front end’ was damaged by overload.

I appreciate your thinking.
Sorry. Much of this is hard to explain, chronologically and or what not. But the GTR 200 Com-2 has always been fine (great) on range of reception. Only issue was the popping, but last week found that out to be the ill spark plugs with screw tops, and maybe possibly ill pushed on plug wire boots. But anyways, the popping root cause has been found and fixed. Both radios are finally "popping" free.

However, I appreciate what you are eluding to with the "damaged front end".
Right now I am waiting for a reply from Garmin on how the heck to do the connections for the transmit interlock that they and another person directed me to connect. Problem is there are ZERO drawings that speak anything remotely related to the 650xi to the gma245R audio p, and the gtr 200. I possibly deduced the wiring, but not going into the bowels of 7th level of **** of removing the panel to add & pin those wires until someone of authority and experience gives instruction or validates my wiring interconnect sketch, or better yet Garmin addresses something of the like.
I've had the entire panel out of this 8 three times now. Just not going back in to the **** of this panel until I get a proven solution.

[BobTurner]

Straightforward: run a single wire from the ‘interlock’ pin on the GTN to the push to talk wire going into the GTR. When the PTT line goes to ground, the GTR can transmit and the GTN will have reduced sensitivity.
I wonder if the gtn interlock pin is accidentally grounded?

[g3xpert]

Originally Posted by ksdflying

I appreciate your thinking.
Sorry. Much of this is hard to explain, chronologically and or what not. But the GTR 200 Com-2 has always been fine (great) on range of reception. Only issue was the popping, but last week found that out to be the ill spark plugs with screw tops, and maybe possibly ill pushed on plug wire boots. But anyways, the popping root cause has been found and fixed. Both radios are finally "popping" free.

However, I appreciate what you are eluding to with the "damaged front end".
Right now I am waiting for a reply from Garmin on how the heck to do the connections for the transmit interlock that they and another person directed me to connect. Problem is there are ZERO drawings that speak anything remotely related to the 650xi to the gma245R audio p, and the gtr 200. I possibly deduced the wiring, but not going into the bowels of 7th level of **** of removing the panel to add & pin those wires until someone of authority and experience gives instruction or validates my wiring interconnect sketch, or better yet Garmin addresses something of the like.
I've had the entire panel out of this 8 three times now. Just not going back in to the **** of this panel until I get a proven solution.

Both your GTR 200 and GTN 650Xi have an interlock input. When this input is active, the receiver in desensitized. You want to desensitize a radio's receiver when the adjacent radio is transmitting, so you connect the transmit interlock input of either radio to the mic key of the adjacent radio.

Page 25-6 of the AU revision of the G3X Touch Installation Manual includes an example of how this is accomplished for a GNS 430. In this example, the Com 1 Mic Key Output from the audio panel is wired to both the Mic Key input of the GNS 430 (to activate the transmitter on the GNS 430) and the transmit interlock input of the GTR 200 (to desensitize the GTR 200 receiver). In your installation, you will need to splice into the wire for the mic key input of the GTN 650 Xi (GTN 650 Xi - pin 11 on P1003) to create a parallel connection to the GTR 200's Interlock Input (GTR 200 - pin 5 on P2001).

To simplify things a little bit, the GTR 200 radio has both and transmit interlock input and output. The transmit interlock output can be used in place of tying into the adjacent radio's mic key input. The transmit interlock output from the GTR 200 (GTR 200 - pin 4 on P2001) is connected directly to the transmit interlock input of the GTN 650 Xi (GTN 650 Xi - pin 9 on P1003).

Thanks,

Justin

[NTex]

Originally Posted by ksdflying

I was hoping the original poster would have replied too perhaps with a finding.
But as for me, 1. No the 1/3rd range issue of the gtn 650xi did NOT move any of the times I swapped antenna coax connections. 2. No the problem does NOT clear up with swapping antennas, ...furthermore when I totaly removed the 2nd Com, the gtr 200 out of its rack, pulled its breaker, AND removed its antenna from the plane, it did not change.

Check the squelch settings. I had the same problem. To ident the problem in my plane, I hit the knob button on the upper left to activate open squelch and I could hear the radio transmissions. I didn't realize I had a problem until I'd get a handoff and checkin with a new approach controller and didn't hear anything back. So I narrowed the problem down to squelch.

The Xi appears to have a default squelch of like 57%... which for most applications is way too high.

Try this:

CONFIG mode
COM
Rx Squelch mode: Basic
Rx Squelch: 15% (down from 57%)

save config, reboot, test fly, report back.