BNC Connectors - A Cautionary Tale
Posted: Tue Jan 13, 2015 8:31 pm
Admin edit: Originally posted within a Summer FD topic, but excellent information worthy to be copied into a topic of it's own
BNC CONNECTORS - A CAUTIONARY TALE
Not sure if this post should go here (Contesting) or in the (Components Category)
In order to try and simplify (eliminate mistakes) setting up of our microwave equipment, we have tried to standardise the use of various connectors.
(1) 12 volts = 6 pin Molex
(2) 28 volts = 12 pin Molex
(3) GPS locking (10MHz) = BNC
(4) 2mx IF = PL259/SO239
(5) Power controls/switching = 9 pin Molex
(6) 1.2/2.4 GHz = N connectors on FSJ4-50 cable
(7) Rotator cables = Amphenol C16 7 pin connectors and caravan cable
(8) 3GHz and upwards = SMA
Last Spring FD was very windy and we noticed that at times, the 3/5/10 GHz transverters seemed to drop level and/or drift off frequency. (intermittent)
So before this Summer FD I investigated the issue, trying to reproduce the problem and was able to do so.
The issue concerned the BNC connectors used for the 10MHz GPS lock signal AND the 145 MHz IF into the transverters (DEMI) that use BNC sockets.
I discovered that the BNC plugs that I was using were a loose fit in the BNC connectors = intermittent problems.
After a lot of research and discussion with knowledgeable persons, it transpires that there are 2 standards for the pin size on BNC male plugs.
I AM NOT TALKING 50 ohm versus 70 OHM - WE KNOW ABOUT THAT!
NO, it appears that there are both 0.9mm and 0.7mm pins being used by the various manufacturers (predominantly Chinese sourced). In my case, the 0.7mm pins were being plugged into USA manufactured sockets that required 0.9mm pins. Ordinarily this would not be a problem, but with gale force winds moving cables around, the plugs could get into positions where they were not contacting properly.
The solution was to replace the BNC socket with an SMA socket for the IF out/ and up the level of the 10MHz GPS lock signal and all is now well, as evidenced last weekend in the Summer FD.
I have tried all sorts of manufactured BNC leads and various suppliers BNC plugs, and there is no clear pattern as to why some are a tight fit and others not.
SO IF YOU ARE USING BNC LEADS IN CRITICAL APPLICATIONS LIKE RECEIVE IF OUTPUTS, CHECK FOR RELIABLE CONNECTIONS.
Cheers
Peter VK3QI (VK3ER/p)
BNC CONNECTORS - A CAUTIONARY TALE
Not sure if this post should go here (Contesting) or in the (Components Category)
In order to try and simplify (eliminate mistakes) setting up of our microwave equipment, we have tried to standardise the use of various connectors.
(1) 12 volts = 6 pin Molex
(2) 28 volts = 12 pin Molex
(3) GPS locking (10MHz) = BNC
(4) 2mx IF = PL259/SO239
(5) Power controls/switching = 9 pin Molex
(6) 1.2/2.4 GHz = N connectors on FSJ4-50 cable
(7) Rotator cables = Amphenol C16 7 pin connectors and caravan cable
(8) 3GHz and upwards = SMA
Last Spring FD was very windy and we noticed that at times, the 3/5/10 GHz transverters seemed to drop level and/or drift off frequency. (intermittent)
So before this Summer FD I investigated the issue, trying to reproduce the problem and was able to do so.
The issue concerned the BNC connectors used for the 10MHz GPS lock signal AND the 145 MHz IF into the transverters (DEMI) that use BNC sockets.
I discovered that the BNC plugs that I was using were a loose fit in the BNC connectors = intermittent problems.
After a lot of research and discussion with knowledgeable persons, it transpires that there are 2 standards for the pin size on BNC male plugs.
I AM NOT TALKING 50 ohm versus 70 OHM - WE KNOW ABOUT THAT!
NO, it appears that there are both 0.9mm and 0.7mm pins being used by the various manufacturers (predominantly Chinese sourced). In my case, the 0.7mm pins were being plugged into USA manufactured sockets that required 0.9mm pins. Ordinarily this would not be a problem, but with gale force winds moving cables around, the plugs could get into positions where they were not contacting properly.
The solution was to replace the BNC socket with an SMA socket for the IF out/ and up the level of the 10MHz GPS lock signal and all is now well, as evidenced last weekend in the Summer FD.
I have tried all sorts of manufactured BNC leads and various suppliers BNC plugs, and there is no clear pattern as to why some are a tight fit and others not.
SO IF YOU ARE USING BNC LEADS IN CRITICAL APPLICATIONS LIKE RECEIVE IF OUTPUTS, CHECK FOR RELIABLE CONNECTIONS.
Cheers
Peter VK3QI (VK3ER/p)