On Wed, Mar 16, 2011 at 4:51 AM, Bob Camp <li...@rtty.us> wrote: > The wonderful thing about a TBolt is that it can use foam core TV satellite > coax. Since 75 ohms is lower loss than 50 ohm (all else being constant) you > can get away with quite a bit of the stuff. F connectors are easy to do > wrong, so get some good ones and a proper crimp tool. Most antennas are TNC > or N, so you will need an adapter. Again - get a good one.
What you really care about with antenna cablbe is the total loss. Given the gain on the antenna and the requirements of the t-bollt reciever you have a budget in dB to work with. Stay within budget. Loss comes from two things (1) any cable will have a loss measured in DB for foot at the 1.5GHZ frequency. This and your budget will limit the length of cable you can use. If a given cable type has to much loss then you need to buy the more expensive kind. If you are lucky you might be able to use that cheap RG8 cable TV stuff but if you have a lower gain antenna and a longer run of cable then you might need LMR400 at 4X the price. All that matters is that you keep the loss in-budget. (2) connectors and adapters have loss too. You get the least loss by using the correct ends on the cable so no adapters are required. It all depends if you need to care abou the last dB of loss or not. I think the best setup is to put a 1" iron pipe on the roof that is taller then any other vents or pipes up there but not so tall you can't reach and work on the top. Mount the antenna on that pipe and run the cable trough the pipe, through the roof and then straight down to the living space in the house. Ideally the antenna cable run would be a short perfectly vertical run but that is unlikely. But still you want the t-bolt in the living space and the antenna high on the roof and the cable run minimized. Once you know the length of cable then you can decide on the lowest priced cable that still has a low enough loss. -- ===== Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.