Hi again Curt, >From what you say your overall, top outside to bottom outside - Not C to C, >dipole measurement would be about 11-9/16" or 11-5/8" if you add the 3/16" x 2 >for the half diameter of the 3/8" alum tube. I'm also assuming that you >pulled a tape or measure across the center support tube and in doing so picked >about a 1/16" because you weren't measuring a true flat plane. If the out to >out dimension is about 11-9/16" you may have one of the original 440-450 set >of dipoles on the UHF portion. I don't know when DB discontinued making them >in the Ham/ Mobile Phone band but maybe someone else does.
The same would hold true for the VHF diploes, 35", - 1/16" for measure correction, + 3/16" x 2 would equal about 35-5/16" overall which puts it in the 140 to 150 range. Looks like you have a winner for 2/440 Ham operation with each half giving you about 6 DB gain and Omnidirectional pattern. I'll send you some info on the measurements direct in a few minutes. Doug N3DAB ==================================================================== --- In [email protected], Curt Seaton <seat...@...> wrote: > > Good day again, Doug, I will not be able to measure the SWR for a few > weeks as it is raining now and I will be out of town for a couple of > weeks, but I did measure the dipoles. Here is what I measured. The > two meter dipoles are 35 inches centerline to centerline top to bottom > per dipole, with the spacing between the bottom of the top dipole to the > top of the bottom dipole being 31 inches. The 440 dipoles are 11.25 CL > to CL and the spacing between the top dipole and the third dipole > directly under it is 38 inches. Remember the 440 is two dipoles at the > top of the pole, the second pair of dipoles is rotated 90 degrees with > respect to the top pair, then the third pair is directly under the first > pair and the fourth pair is directly under pair number 2. Hope this > helps in identifying your antenna. I will forward you the swr plots > when I return and can set up to do so. I will also take photos... > > Regards > > Curt > > n3dab wrote: > > Hi Curt, > > > > Yes, that is the way I recall seeing the Dual Band antenna in the old DB > > products catalog. Have you tried checking the upper and lower halves to > > see what kind of SWR you have at the operating freq. ?? If it is convient, > > measure the end to end length of the upper and lower dipoles. The UHF > > diploes should be about 11-3/16" for the 450-470 MHz. The VHF dipoles > > should be 37" for 138-150 or 34-3/16" for 150-160 MHz. 155-165 MHz is > > 33-3/4" and 164-174 MHz is 31-3/4". > > > > For some reason the UHF 450 -470 versions are very broad banded but the VHF > > versions seem to be more critical pobably due to the harness construction > > more then the dipole length. > > > > Thanks for the input. > > > > Doug N3DAB > > > > ===================================================================== > > --- In [email protected], Curt Seaton <seatons@> wrote: > > > >> Good day Doug. I have a DB dual band antenna similar to what you are > >> describing, it has 4 folded dipoles for two meters, and 8 folded dipoles > >> for 440. These are two on each side of the pipe for two meters and four > >> on each side of the pipe for 440. The diameter of the pipe is slightly > >> smaller for the 440 section. The exact model number is not readable > >> (scraped during mounting or dismounting) but it sounds like what you are > >> looking for. IF this is the same as you desire, mine does have TWO > >> different feed lines coming down to connect to your VHF and UHF radio > >> systems. The pipes are concentric with a wedge shaped mount and held in > >> final position with gravity and hose clamps. Keep us all posted on your > >> endeavors as we are looking for the same scenario for D star here.... > >> starting with the B module and adding C later... gotta recover > >> financially first... > >> > >> 73 > >> > >> Curt > >> W1FSM > >> > >> n3dab wrote: > >> > >>> I know DB made a dual band 150/450 folded dipole antenna (bottom half was > >>> either a DB-222 or the bottom half of a DB-304 and the top half was a > >>> DB408 or top half of a DB-420), which is no longer available. Does > >>> anyone recall whether it was fed with one feed line or two ? I think it > >>> was 2 but, I can't recall the dipole configuration (singles on opposite > >>> sides going up, or pairs at each level). > >>> > >>> I would like to combine a DB-224E (138 -150) with a DB-408 or DB-420 > >>> (450-470) on a single mast, or split the antennas at the mid point and > >>> make 2 antennas with the VHF on the bottom and the UHF on the top, and > >>> the reverse on the second antenna. Has anyone tried this ? What were > >>> the results ? The numder of feed lines (1 or 2) to the antenna is not an > >>> issue at this time. > >>> > >>> The combined antenna would be for a 2 Mtr./440 D-Star application becuase > >>> of limited tower space available. > >>> > >>> Comments appreciated > >>> > >>> Doug N3DAB > >>> > >>> > >>> > >>> ------------------------------------ > >>> > >>> > >>> > >>> Yahoo! Groups Links > >>> > >>> > >>> > >>> > >>> > >>> > > > > > > > > > > ------------------------------------ > > > > > > > > Yahoo! Groups Links > > > > > > > > > > >
