Gainmaster issues

[Mudfoot]

Are there any issues with a GM that affects it without disturbing SWR? Mine seems to be working like it should, I'm getting common mode type interference from it now. Haven't had that issue before. Wasn't sure if something inside that would breakdown and cause that. We've had some high wind/rain events recently. Maybe worked something loose.

 

[bob85]

I can't think of anything inside the antenna failing that would cause cmc but not effect vswr,

what makes you think its cmc, it could be,

a choke does not perfectly decouple the antenna as claimed, chokes are reactive,
with the right length mast/coax they can work great with very high choking impedance,

BUT with some mast/feed-line lengths the choke can increase cmc significantly by resonating the coax or mast,

Assuming it is cmc & its suddenly increased to a level where its causing issues,

did you change anything in the whole system from tip of antenna through mast & coax & equipment to ground ? added a bit of kit & jumper, ground wire, or took something out of line ? change mast length,

just a thought, you have not taped the choke up & got it full of rain & dirt have you?

good luck finding the culprit.

 

[Mudfoot]

Haven't changed anything. It's been working fine. Just starting to see RFI in the shack. First problems since putting it up. I have been wanting to add new run of LMR-240, but haven't had time.

 

[bob85]

what about grounding, could a ground rod have dried out or got wetter than usual, something must have changed, maybe not even something in your cb system,

i once lost ground when the water board put a plastic coupling between the old pipe feeding 3 houses & the water main.

 

[Mudfoot]

Going to just pull it down and inspect it. It it looks OK, I'll add my new coax and go from there.

 

[Shockwave]

This is most likely a loose connection on the braid of the coax. If the PL-259's are not completely tight anywhere in the system, RFI will become present long before you see it with high reflected power. These connectors are notorious for this problem where the "N" type, never has this problem.

 

[Mudfoot]

Terminals in shack look good. Once this windy weather stops, I'm taking it down. Been having high winds off and on for a week. Maybe the flexing got to it. I'm on dipole for now.

 

[bob85]

Do you solder the braid or just twist plug on ?,
nobody near me bothers soldering the braid & can't understand why i bother soldering mine.

 

[Mudfoot]

Do you solder the braid or just twist plug on ?,
nobody near me bothers soldering the braid & can't understand why i bother soldering mine.

The past few years I've been using quality crimp connectors. I still solder the center.

 

[543_Dallas]

I have a friend that just screwed connector over the shield. He had high swr every summer. It was like clockwork after rain season.

I've been using crimp connectors for a couple of years also. No issues yet but I seal everything and seal it again. The oldest one has only been in the air since November 2016.

 

[Blackcat630]

I guess I'm old school.. got a ton of Amphenol screw ons from my wife's uncle (sk). I get out the ol Weller gun, dab on some flux and solder the braid and center. This has worked for me for years. I'm also a firm believer in proper weather sealing for outside applications.

 

[543_Dallas]

I guess I'm old school.. got a ton of Amphenol screw ons from my wife's uncle (sk). I get out the ol Weller gun, dab on some flux and hit the braid and center. This has worked for me for years. I'm also a firm believer in proper weather sealing for outside applications.

Nothing wrong with that. I was talking about the guys that fold the shield back over the cable and screw the connector over the shield.

 

[Blackcat630]

Nothing wrong with that. I was talking about the guys that fold the shield back over the cable and screw the connector over the shield.

Got ya.. yeah I dont go that route

 

[Mudfoot]

I guess I'm old school.. got a ton of Amphenol screw ons from my wife's uncle (sk). I get out the ol Weller gun, dab on some flux and solder the braid and center. This has worked for me for years. I'm also a firm believer in proper weather sealing for outside applications.

I've done that before with good results.

 

[bob85]

I presumed most people using screw on plugs with holes to solder the braid did solder theirs or at least tried to solder it,
turns out that they don't, folding the braid back & screwing it on is the norm sometimes you can't see the braid through the holes,

watching videos of people soldering pl259's most people even Ten-Tec & shops over here make hard work of it by using farty little irons for the braid.