Extremely interesting and pertinent thread!
Our story is this:
- Archer antenna in the right wingtip of a 7A.
- We're basically day VFR only, by regulations, but with a Navcom / ILS receiver as an "exit strategy" should that some day turn out to be the safest way down. Or simply to use / practice VOR navigation / backup to GPS... Hence the NAV is not regularly used e.g. for IFR operations, so operational experience is somewhat limited.
- Had an SL30 installed for 14 years (it's still for sale btw ;-) and had done a few practice approaches every once in a while, without any problems. Reception was always decent, and glideslope alive at the FAF/FAP.
-Recently, replaced the SL30 with a modern Trig TX56, mainly due to the 8.33KHz COM channel spacing in Europe, which rendered the COM portion of the SL30 not usable.
-While the localizer/VOR reception is excellent with the TX56, GS reception has been crappy from the start.
I'm in touch with Trig and they are extremely helpful / supportive and responsive.
So we did some diagnosing and trials, even with a replacement unit! And it turns out that it must be an issue with GS reception/signal strength. Range is only about 5-6NM from threshold for the GS of an ILS, which is obviously between useless and dangerous...
Also, as soon as i've intentionally deviated slightly high or low, reception drops out. Equally useless.
During this year's annual maintenance, I've added a grounding strap to improve the ground conduct between the airframe and the antenna base.
This did help massively with the morse code / nav audio reception & clarity. Unfortunately, it didn't solve the GS issue...
View attachment 63610
I'm extremely interested to learn more about the modifications
@ewumnrr did.