Remote Rig

RRC 1258 Support in English => General discussion forum => Topic started by: G3UEG on 2010-10-05, 15:17:11

Title: Connecting the screen/shield on a DB9 RS232 cable
Post by: G3UEG on 2010-10-05, 15:17:11

Because of ongoing RFI problems I want to replace the RS232 cable between the RRC and the SPE Expert amp with a screened lead.

1) Question for Mike..
  Is the shield of the female DB9 connector of COM1 connected internally to the ground pin 7?  If not what is it connected to?

2) How do I connect the screen of the 4-core cable, there is no obvious connection point on either the DB9 male plug itself or the metal shell in which it is fitted? and do I make this connection at both ends or just one? and if just one which end?

73,
Dave, G3UEG

Title: Re: Connecting the screen/shield on a DB9 RS232 cable
Post by: sm2o on 2010-10-05, 16:03:31

Because of ongoing RFI problems I want to replace the RS232 cable between the RRC and the SPE Expert amp with a screened lead.

1) Question for Mike..
  Is the shield of the female DB9 connector of COM1 connected internally to the ground pin 7?  If not what is it connected to?

The shield is not directly connected to gnd pin 5 it's only directly connected to the housing.

2) How do I connect the screen of the 4-core cable, there is no obvious connection point on either the DB9 male plug itself or the metal shell in which it is fitted? and do I make this connection at both ends or just one? and if just one which end?

There is no right or wrong in this matter, if I say one thing the opposit is probably the best in your case, you have to try

73 de mike

Title: Re: Connecting the screen/shield on a DB9 RS232 cable
Post by: G3UEG on 2010-10-05, 16:15:32

Mike,

Thanks for replying..

In my documentation Pin7 is ground and Pin5 is CTS  was your reply a typo, or is the RRC wiring different?

73,
Dave, G3UEG

Title: Re: Connecting the screen/shield on a DB9 RS232 cable
Post by: ON4AOI on 2010-10-05, 16:48:15

Hi Dave,
pin 5 = (signal) gnd for sure

Solder the shield on both ends directly to the rs232 connector
(on good quality DB connectors it works perfect). In this case
all metal boxes are at same potential before any other connection
is made.

Guy ON4AOI     

Title: Re: Connecting the screen/shield on a DB9 RS232 cable
Post by: G3UEG on 2010-10-05, 17:21:18

Hi Guy,

Thanks for the info..

73,
Dave, G3UEG

Title: Re: Connecting the screen/shield on a DB9 RS232 cable
Post by: dj4mz on 2010-10-05, 17:44:39

Hi,

from theory: You should have a "real" GND connection from one connector to the other and additionally a screen which is connected to GND on only one end.

vy 73 de Simon (DJ4MZ)

Title: Re: Connecting the screen/shield on a DB9 RS232 cable
Post by: ON4AOI on 2010-10-05, 19:26:40

Hi Simon
like you said in theory .... ..
In my setups I have best results when both sides are connected

Guy ON4AOI