Uniden Washington Base Station

[Capt. Kirk]

I'm not going to touch the radio or antenna at all. I'll hook that ground back up and see if that does anything with the 2.0 SWR and post the results here.

Got an end today and will solder that on as soon as I can. We've got storms coming so I'll wait it out. Was gonna buy a new braided cable but apparently they must have a little gold content in them. This begs the question. Why do these ground straps need to be braided? I'm sure there's a reason but I don't know why.

 

[Cable Guy]

I think it's a surface area thing, like RF travels on the outside of the conductor, see "skin effect". Smaller wire braided has more surface than a large solid conductor. I could be mistaken though as I am often wrong.

 

[Smokinone]

Got an end today and will solder that on as soon as I can. We've got storms coming so I'll wait it out. Was gonna buy a new braided cable but apparently they must have a little gold content in them. This begs the question. Why do these ground straps need to be braided? I'm sure there's a reason but I don't know why.

Braided wire is less likely to break under vibration

 

[DTB Radio]

I think it's a surface area thing, like RF travels on the outside of the conductor, see "skin effect". Smaller wire braided has more surface than a large solid conductor. I could be mistaken though as I am often wrong.

I used to believe that braided was better than solid because of the surface area. A well-seasoned and well-educated fellow ham in my area told me that a plain old copper wire, the larger the better, works just as well if not better for RF.

Thanks for the reply. It raises another question that I was gonna ask later because it's not about the Washington. I installed a small Cobra 19 in my Jeep recently and have it hooked to a 4' Firestick. I cut the excess coax and resoldered the tip. I checked grounding and continuity and everything seems OK. The SWR was way off. I clipped wire out of the tip a little at a time and got things at 2.0 on 1, 1.8 on 20 and 2.0 on 40. My understanding is that the goal is to balance SWR on 1 and 40. 2.0 seems high to me still but I don't know what to do about it. I don't know if me cutting the coax is causing this problem. I bought a K-30 with magnet base for a portable system I'm working on. I was gonna try this in the Jeep to see if it makes a difference. Thanks for your help.

Cutting the coax can and usually will affect what the SWR meter shows, but it does NOT affect the actual antenna SWR. The only thing that can change the SWR at the antenna is something that directly affects the antenna itself (or the grounding), IE relocation of the antenna, trimming or adjusting the antenna, damaged antenna, mounting stud issues, etc.

One other note, using coax with poor shielding will give a lower-than-actual SWR reading, as the RF leakage/loss occurs both going and and coming back in. This makes the reflected power lower at the meter than at the antenna. This will be more of an issue with longer runs of cable such as on a base station, but not as much of an issue with the short lengths used on a mobile.

 

[Capt. Kirk]

told

I used to believe that braided was better than solid because of the surface area. A well-seasoned and well-educated fellow ham in my area told me that a plain old copper wire, the larger the better, works just as well if not better for RF.




Cutting the coax can and usually will affect what the SWR meter shows, but it does NOT affect the actual antenna SWR. The only thing that can change the SWR at the antenna is something that directly affects the antenna itself (or the grounding), IE relocation of the antenna, trimming or adjusting the antenna, damaged antenna, mounting stud issues, etc.

One other note, using coax with poor shielding will give a lower-than-actual SWR reading, as the RF leakage/loss occurs both going and and coming back in. This makes the reflected power lower at the meter than at the antenna. This will be more of an issue with longer runs of cable such as on a base station, but not as much of an issue with the short lengths used on a mobile.

I know welding cable has a lot of very fine wires and a little research says that's because it's more flexible which makes sense. It may be the same reason for grounding straps.
I haven't had a chance to reattach that ground strap so I don't know if it's gonna change anything yet. I would guess there's about 6' of coax between the antenna and radio.
On another note, I have a base station that has 100' of coax and I only needed about 60'. I've got the rest coiled up in a circle maybe 8-10" in diameter and zip tied together. I recently discovered doing this isn't good. It was suggested to make a 2' figure 8 loosely tied at the center. My SWR on that radio is very low...1.1 or 1.2...so I may not have as good of an SWR that I think??