Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KQ0J, Jan 22, 2020.
Well, at least we know copper theives weren't the culprits. On the other hand, underground varmints just love insulation. and the sticky floodant inside DB coax tastes like dessert to them, apparently.
Any gophers or squirrels hanging around your friend's QTH?
These are just my long-term observations about feedlines. Nothing scientific. But, I'm not sure I've had any particular antenna in use for more than 4 years, and that goes back about 60 years. That is a lot of antennas and a lot of feedlines. I've never worried about rotted coax, window line, twin lead, etc. It happens.
Disclaimer: I never run more than 100 watts output.
For probably the about last 15-20 years I've moved almost exclusively to feeding my unbalanced antennas with some version of satellite TV or CATV coax. Yes, it is 75 Ohm. If I need lower impedance, such as for a 1/4 wave vertical, I can use the satellite twin version coax which comes out to 37.5 Ohms when properly configured. The best thing is that this coax is usually free, or available for nearly free. It is very low loss. The orange stuff is meant for direct burial. Even the stuff that isn't meant for direct burial outlives my antennas. Except for color changes to match the soil, when I pull it out of the ground a few years after I installed it, it still looks pretty reasonable.
I often find 25, 50 and 100 foot pieces of RG6 coax that have good weather proof Type-F connectors on each end. I don't use them with the connectors buried below ground. Above ground I usually adapt them to BNC or PL-259. They get coated with a good slathering of "liquid electrical tape". Probably more than 40 years ago I standardized on BNC connectors for nearly everything I do at home. Crimpers and BNC connectors are also very inexpensive at most big-box home improvement stores.
One of my biggest disappointments with feedline came a couple of years ago. I had a NIB (new in box) 100 foot roll of 450 Ohm #16 window line. I bought it as surplus in Oakland, CA sometime in 1969-1970. It probably wasn't even 60 years old. I pulled it out of the box and the brown plastic fell into thousands of little pieces.
I've run RG6 72 ohm coax hundreds of feet and use F-Type to PL259 connectors and they will handle quite a bit of power.
My 160 and 80 meter Four Squares both use RG6 phasing lines.
Direct burial without putting it in conduit has always cause me problems with underground animals/rodents.
I've never had good luck with RG213 direct burial, the LMR 400 and 600 cable has always been much better over a longer time.
I have thousands of feet of cable but the cable that's underground is in conduit, every cable I ever buried ended up failing, that was not in conduit.
If you don't bury it deep enough in Northern climates, soil freezing and unfreezing movement will eventually move the jacket on the coax and cause damage, other areas soil erosion and rocks can damage it.
K0UO Rhombic Antenna Farm is located at the Kansas QTH with over Two miles of Wire in the Air & On the Air,
E.C. Wenger Electronics on Webster Street, by any chance? One of my old hangouts when I was I a kid.
Steven -- maybe you need more feral cats on the farm!
I know not everyone will agree with this, but I've spent all but a few years of my life in rural areas, usually on some kind of farm with acreage. We've always had a house cat or two, some favorite barn cats, and the usual amount of feral cats. They sure keep the rodent population down. My bride has always appreciated them, plus chickens and guineas, because they all seem to greatly enjoy keeping long and slender legless critters away from the house.
For anyone who has a tractor with at least a Cat-1 3-point hitch, it is really easy trench or put in a ditch, including for cable or conduit using a middle buster, pipe-layer, or sub-soiler. At auction, these implements typically go for about $50. I think they now also make them for 4-wheelers and other types of UTVs.
BTW, looking at the photo, that coax was definitely not "direct bury" coax.
"DB" coax has a flooding bonding agent between the outer jacket and the braid, and makes it very difficult to even peel the braid off. I don't normally use it, but have used it, and "stripping" it is a real PITA and doesn't take five seconds like it does with ordinary RG-213/U or any other standard cable.
People can claim whatever they want, and even "labeling" coax is no-cost to the reseller or distributor if they buy 1000' reels of it -- the factories will all label cable any way you want.
Real DB cable doesn't look like that. Although real DB cable can still be destroyed by sharp rocks, moles, gophers, etc. Some animals that spend a lot of time underground also have very sharp teeth and claws that can dig through almost anything except solid rock.
It is so long ago, I don't remember much about them. There were two electronics surplus houses on a pier in Oakland. One was in a shack and one was in a quonset hut. They were there at least from before 1970 to after 1974. There was also another electronics surplus house on Market St., in downtown San Francisco during that same time. I'm thinking it was near the corner with Van Ness. There was also a great electronics store within a block of that. I'm sure none of my mind memories look like it did back in the 1970s.
I still have a number of great ageless RF and electronic items from those places.
I was working on a ship at one of the Oakland piers sometime in the early-mid 197os when I went into one of the Oakland surplus stores. There was about a 12"x 12" x 8" cardboard box on the floor of the store (I still have the now half-filled box). I believe they wanted $0.10 per pound for the contents. It was almost 50 lbs. I bought it. It was filled with multiples of virtually every kind of coaxial adapter in use around 1970. My biggest problem was getting it back to Honolulu as a "carry on" item.
I also did consulting, some development work, and writing for a couple of crazy guys in Oakland in the early 1980s. I don't remember who did what. One of them took over the old quonset hut surplus electronics outlet on the Oakland pier. I think that might have been Bill Godbout selling surplus computer parts (eventually, I think it became CompuPro). If not, it was George Morrow (Thinker Toys). As a hobby I wrote for crazy little magazines like Micro Cornucopia, and Morrow magazine for a few years, and probably a number of others I don't even remember. I sold kits that went with Godbout's and Morrow's computers. I probably wrote for Byte, because I advertised some of my various kits in Byte.
The coax and radials I laid in those days has probably all turned to compost or underground hazardous materials.
Wow, Ken; It's truly a small world. I never went to that surplus store that you mentioned---but I do remember the quonset hut one out by the old "Amelia Earhart" Oakland Airport as well as the big electronic surplus store on Market St. in SF. There was also Lafayetter Radio Electronics down So. of Market on 9th St. as well. Fun places all.
Zack's Electronics was further up Market near Van Ness (!) and where I got my first ARRL Antenna Book in 1965 which I still have (a bit worn by now!).
After a couple years of working my first job at the Oakland Tribune (several years later) I also eventually left Oakland on a ship bound for Honolulu and thus began my love for the Islands...
73 and Aloha-ha-ha,
" Real DB cable doesn't look like that. "
I am sure that's correct - my guess is that either he got scammed or used what was available. It now has RG-213 DB from Wireman I think was the label . Its about 100' to the antenna
I only cut the trench down to 4-6 inches with a Mattock pick - no freezing here and soil is about half sand.