In article ,
"Robert11" wrote:

Hello,

Should have asked this also in my previous post re 50 or 75 ohm coax,
but I guess it is probably better to start a different thread. New at
this, so please pardon these very basic type of questions.

For a receiving only application, 30 MHz on down: Putting up a new
Inverted-L receiving antenna.

Radio, Balun, Lightning Arrestor use the 259 type of plug which I
guess is nominally for 50 ohm systems.

I can go with 75 ohm BNC connectors for the main coax run, but am
pretty well stuck with the 259 type for the already purchased units I
noted above.

Intuitively, I guess I would like (all) 75 ohm connectors if I am
using 75 ohm coax.

But, for 30 MHz and lower listening, would I even notice any
difference, probably ?

Is any received signal lost, or reflected back, at these 75-50 ohm
junctions ? If meaningful, any way around the problem ?

Technically yes you will lose signal power in your antenna system with
each incorrect connector. WIth several wrong connectors the situation
gets complicated with multiple reflections in the antenna system.
Practically though the connectors have a very short electrical length at
30 MHz and lower so the effect of impedance mismatch will be small.

The best thing to do is use all the right stuff. Use the right cable and
connectors.

Using the wrong stuff has another complication in that you can have
mechanical trouble putting connectors on the coax. Mechanically things
may not fit well or at all. Connectors are designed with a size coax in
mind where 75 and 50 coax are not of the same dimensions.

BNC connectors are more commonly 50 ohms.

--
Telamon
Ventura, California