Great resource and timing , I just finished ' Tuxedo Park ' and now know where the L in Loran came from
Steve --- On Mon, 3/15/10, Bruce Griffiths <[email protected]> wrote: From: Bruce Griffiths <[email protected]> Subject: Re: [time-nuts] Choke Ring Pictures To: "Discussion of precise time and frequency measurement" <[email protected]> Date: Monday, March 15, 2010, 1:34 PM For some idea of the considerations involved in selecting materials for and designing a radome see: http://ia331316.us.archive.org/0/items/radarscannersand033384mbp/radarscannersand033384mbp.pdf A list of the properties of some dielectrics at microwave frequencies in inluded. Bruce Bob Camp wrote: > Hi > > Any idea what the funnel was made out of? Some plastics aren't real great at > microwaves... > > Bob > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Brian Kirby > Sent: Sunday, March 14, 2010 8:50 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Choke Ring Pictures > > The home made choke ring was calculated and the pie/cake pans came > close. I think somebody all ready pointed at it, but Unavco or NASA had > the dimensions to about 6 or 8 common choke ring reflectors on line. > > They are aluminum cake pans - I bought them in a crafts store. They are > one inch apart between the rings. They are 2 inches deep at the rims. > The outside pan is 12 inches (measured inside). Next is 10 inch, then > 8 inch, then 6 inch, and 4 inch. > > When making them, I found the center of each pan and then drilled them. > Then I used a bolt to hold them all together except for the very center > unit. Then I drilled two holes about and inch from the center and used > thin long bolts to attach them to a piece of square tubing on the > bottom. The alignment bolt was removed from the center hole and > drilled out larger to pass the antenna coax thru. The very center > pan, I used epoxies to glue the antenna too and I used a clamp to hold > it in place. Then the coax was pass thru a hole I drilled out thru > the center holes of the other pans. Then I glued the antenna pan to > the other pans and used several blocks of wood to center the pan and a > big piece of pipe and weights as a clamp to hold it down while it was > curing. The square tubing was aligned into a laser level mount and > epoxied and that allows the unit to be attached to a tripod. The mount > has three adjusting screws that allows the antenna to be leveled. I > used the units in pairs when surveying and always aligned then north in > an attempt to bias out centering differences. > > The first unit mounted on the house roof did have a drainage problem the > first time it rained. I drilled 1/8 holes inside of each ring to let it > run out. That was not the worst problem. A bird decided it would make > a good home and started building a nest on it when I went on vacation. > I bought a large plastic funnel and inverted it and glued it inside of > the outer ring to stop that. > > The antenna is the common Antenna97 from Motorola, the coax was cut at > about one foot (I think it was originally 18 feet long) and a connector > was attached. I then used a very low loss coax (1/2 inch heliax) about > 40 feet long to bring it into the basement. > > Brian - KD4FM > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
