[time-nuts] TNC connectors

GandalfG8 at aol.com GandalfG8 at aol.com
Tue Jun 23 10:00:49 UTC 2009

In a message dated 23/06/2009 09:29:38 GMT Daylight Time,  
david.partridge at dsl.pipex.com writes:

The  T-Bolt manual recommends 75 ohm coax, so will a 75 ohm TNC mate with a
50  ohm TNC without problems?   Though I suppose for a short run of  cable, 
ohm will be OK?

Hi David
There's been some previous discussion on this, perhaps an archive search  
will throw up past comments, and probably with usual Time-Nuts  overkill:-).
According to the manual the Thunderbolt antenna input impedance is 50ohms,  
despite their using an F connector, but they recommend using 75 ohm cable  
on the basis that it tends to have lower loss for a given size.
Unless you're planning on really long runs I'd suggest just sticking with  
50 ohm cable and connectors.
I've got a couple of commercial antennas that come with predefined lengths  
of cable, 20 metres if I remember correctly, and these use RG58.
I'm not sure if you'll get a TNC to F type adapter anyway, so you might  
have to revert to BNC on the cable at the Thunderbolt end.
The mounting pole thread seems to be fairly standard but not sure on  
availability of threaded poles.
One option would be a stub mounting plate as sold for marine  use, one 
current ebay item for example is 250430681103,  and a further search in the 
marine section might prove useful.

More information about the time-nuts mailing list