TNC-Adpater to for optional antenna mounting position
TNC-Adpater to for optional antenna mounting position
(OP)
Hi I was going to use a TNC Adapter to link antenna's to a Radio so that I have the choice of two antenna mounting positions. TNC directly on top of the system/box for 2.4db whip antenna and underneath the system/box for a secdondary to attach a 1 meter cable to, for a larger antenna such as a 6db collinear antenna. Is this a bad idea for any reason, will this be a problem for attenuation/imepdance etc. Or are there any other condiserations needed to be taken into account. Thanks Paul





RE: TNC-Adpater to for optional antenna mounting position
RE: TNC-Adpater to for optional antenna mounting position
The issue isn't the T-connector, it's the significant length of unterminated transmission line hanging off when position 1 is in use. That'll cause reflections, frequency / length dependent cancellations, VSWR, etc.
So no.
RE: TNC-Adpater to for optional antenna mounting position
I mean: yes.
RE: TNC-Adpater to for optional antenna mounting position
Note - the opposite case of the open T is not usually an issue because it's such a short length of unterminate transmission line that it would present an open circuit right up to extremely high frequencies, corresponding to its 1cm length.
RE: TNC-Adpater to for optional antenna mounting position
RE: TNC-Adpater to for optional antenna mounting position
RE: TNC-Adpater to for optional antenna mounting position
You could use an RF switch or relay.
You could install a loop-in connector. Out, jumper, back in and out the other side.
RE: TNC-Adpater to for optional antenna mounting position
RE: TNC-Adpater to for optional antenna mounting position
Switches or relays with (for example) BNC connectors would be more common than TNC. One could mix and match through the signal path. Just because you TNC on the external connectors doesn't mean you can't use other connectors inside.
Or, at such UHF frequencies, one might be able to carefully wire-up a normal low voltage switch, using skillful RF wiring techniques... ...maybe, it's at the hairy edge. But hobbiests were playing with UHF many decades ago using skillfully applied point-to-point chassis wiring and vacuum tubes.
If you space the Out & In connectors just right, then you might be able to make an all-adapter jumper using two right-angle, and one double-male, adapters. Beware this spacing may slightly vary with exact PN of specific adapters used.
eBay has some good suppliers of connectors, adapters, etc.