The low-band loop from Sinclair (SRL 110) was not nearly as wide band as the Hi band (SRL210) and UHF models (SRL310). The latter were designed to be mounted either half wave or quarter wave from the tower or mast. In the case of the low band loop a half wave would have put the loop 10 ft from the mast, which would be structually unsound. The SRL110 were normally mounted about 3 ft or so from the mast which is 1/8 wave. This would result in a lower impedance (<200 ohms loop impedance) requiring 93 ohm coax as an internal matching transformer (the SRL210 and 310 series use 125 ohm matching coax). It also would be much more sensitive to spacing from the mast or tower.
At least that has been my experience with the low band loops. Burt VE2BMQ Chuck Kelsey wrote: > FYI - Sinclair got the extra bandwidth by stager tuning the antenna element > from the 1/4-wave matching transformer that is inside the element. The > trade-off was a decrease in return loss (higher VSWR). > > Chuck > WB2EDV > > > > > ----- Original Message ----- > From: "skipp025" <skipp...@yahoo.com> > To: <Repeater-Builder@yahoogroups.com> > Sent: Sunday, November 15, 2009 10:15 AM > Subject: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212) > > >> If you're building a Low-Band Loop Antenna from scratch... >> forget the DB-212 and copy the Sinclair Version. The >> Sinclair Low-Band loop has a lot wider band-width and it's >> pretty much the same design... if properly done easier to >> construct hardware wise. >> >> s. >> >> >>> "cruizzer77" <atlant...@...> wrote: >>> >>> >>> >>> Thanks for the info. Somewhere else I read that from the mount to the >>> outer edge the length should be 51 inches, this will be about the same as >>> 52.5 inches from center to outer edge. >>> >>> But to build one from scratch I need more info, radius of the loop, >>> diameter of the tube, coupling etc. Of course these can be calculated >>> from formulas, but as the DB212 seems to be a particular good design it >>> would be interesting to know. >>> >>> >>> >>> >>> >>> --- In Repeater-Builder@yahoogroups.com, "JOHN MACKEY" <jmackey@> wrote: >>>> I converted one about 15 years ago for use on 6 meters. It measured >>>> 52.5 >>>> inches from center to outer edge. >>>> >>>> ------ Original Message ------ >>>> Received: Sat, 14 Nov 2009 10:41:05 AM PST >>>> From: "cruizzer77" <atlantis7@> >>>> To: Repeater-Builder@yahoogroups.com >>>> Subject: [Repeater-Builder] DB-212 detailed info wanted >>>> >>>>> Does anyone have detailed info about the DB-212 antenna (converted to >>>>> 6m) >>>> that make it possible to build one from scratch? >>>>> All the measures and info about the mount and feed point are >>>>> interesting in >>>> the first place. >>>>> 73 de Martin HB9TZW >>>>> >>>>> >>>>> >>>>> >> >> >> >> ------------------------------------ >> >> >> >> Yahoo! Groups Links >> >> >> > > > -------------------------------------------------------------------------------- > > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 9.0.707 / Virus Database: 270.14.66/2504 - Release Date: 11/15/09 > 02:50:00 > > > > ------------------------------------ > > > > Yahoo! Groups Links > > > >
