alioth wrote:
You can usually tell if the centre pin is designed to be soldered – it’ll have a little hole in the side of where you poke the coax centre conductor
Actually, such pins are used for both soldering and crimping, and crimping guides explicitly say this hole should be used to check for correct wire insertion depth.
All my Garmin stuff uses the machined pins though, none of the stamped stuff.
This is Garmin G5. The pins are stamped, which is revealed by tiny slits at their tips.
alioth wrote:
All the RF connectors (BNC, TNC, N, SMA) I have use a soldered centre pin and crimped shield. (You can usually tell if the centre pin is designed to be soldered – it’ll have a little hole in the side of where you poke the coax centre conductor).
I was really talking about the braid etc rather than the centre core – which is obviously trivial to deal with by comparison.
I swapped the radio for my “spare” and still the same issue. I’ll check the connection next, I obviously messed up and/or a tiny stand of braid got in the wrong place and shorted the connector. Unusual as I am careful.
It was definitely a solder plug/socket but let’s not start the “crimp” vs “solder” debate again (I’m an old school solder guy)
So my in line BNC connectors were soldered perfectly, it is not the radio. (As I swapped the radio in the tray for my known working spare).
So it can only be the coax which is 40 year old RG58 which has visible oxidation on the braid where the old balun was grounded.
I propose to run a new length of HDF200 . It’s only VHF, “receive only”, perhaps an 8 metre run as the antenna is on the tail so perhaps a decent 5 mm cable like this is OK? https://www.solwise.co.uk/wireless-coax-cable. What do you think @Peter – you will no doubt have strong opinions on cable 
but Solwise will put the plugs on which saves messing about.
I used to have dual NAV comms so is it likely the VOR/ILS antenna went into a diplexer? I need to get remove some trim panels but would this be a typical installation?
I’m assuming the Diplexer has BNC connections? Any help welcome.
Just use RG400 How much do you need? I have been sitting on a good length of it since 2013. I can send you some.
If you put the connectors on first, you won’t be able to run it through any tight spaces, and it might be too long (messy) or worse still too short.
The diplexers I have seen in GA are BNC, yes.
Have you checked with a meter whether the existing cable is shorted to ground?
