In a message dated 29/01/05 16:36:57 GMT Standard Time, [EMAIL PROTECTED] writes:
If you have a balanced antenna system, or even an unbalanced system with RF properly choked off from the outside of your coax, there will be no RF on the chassis that 'as to go somewhere'. In addition, it is very difficult to provide an RF ground at HF. --------------------------------------------------------- With my shack in an upstairs spare bedroom it is difficult to provide an RF ground in any case, the only ground being the power ground. The house is built on rock so I doubt if a ground rod would go in very deep even if I tried. Opted like Vic for a balanced antenna with balanced feeder. Using 100W have not seen any problems unless I try to operate on a band that the antenna is not resonant on. Using 75 ohm balanced twin as the feeder as the use of 300 ohm ribbon or higher would be impractical from my shack. The 75 ohm twin seems quite docile in use and can be installed in close proximity to metallic objects which is not recommended for 300 ohm or higher impedance twin feeder. To date the only interference problem have been with telephones whose drop wires are parallel to my antenna. The phone company fitted RF filters to the affected telephones at the point of entry into the house and one modern telephone had to be suppressed internally. Older telephones seem less affected. A problem that may be coming up is the use of ADSL broadband would probably prevent normal telephone RF suppressers being used at the point of entry to the house as this would also stop ADSL from working. A separate RF filter at each telephone would be the only answer in this case. As a parallel subject there was an interesting article in the February 2005 Radcom, EMC column advocating the use of ADSL telephone filters as being very suitable for use as RF filters on telephones for the lower bands and the performance figures for one type of ADSL filter were quoted. See them available at computer fairs at about £3 each ($5.70 US). Bob, G3VVT _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
