JohnE Posted February 26, 2016 Report Share Posted February 26, 2016 will be conducting an antenna experiment w/575 machine in the near future to see if there is any real difference in pattern and range vs cost. RSSI readings at fixed locations have been taken this week. waiting for the Comtelco antenna to show up.all things being equal the only change will be the antenna itself.the antennas will be a Laird 5dBd($150) currently in serviceComtelco 6dbd ($200)PD 201 5 dBd ($450)the Laird is physically the smallest one, the other 2 are roughly the same size/weight.will post pics of the 3 together.not looking for radical results but it should be interesting.ground elevation ~150'structure ~200' Quote Link to comment Share on other sites More sharing options...
6040 Posted February 26, 2016 Report Share Posted February 26, 2016 I'm tuned in. I happen to have the 6dbd Comtelco. Got burned though, didnt do my home work and bought it straight from Comtelco only to find out I could have saved a hondo from one of thier vendors!oh well, hopefully it compares well in your comparison so it takes some of my sting away...LOL Quote Link to comment Share on other sites More sharing options...
n4gix Posted February 26, 2016 Report Share Posted February 26, 2016 I will be following closely myself, as I know my next expense will be new Superflex and antenna for my new Bridgecom repeater. There's no point at all in putting used tires on a new car! Quote Link to comment Share on other sites More sharing options...
JohnE Posted February 26, 2016 Author Report Share Posted February 26, 2016 I will be following closely myself, as I know my next expense will be new Superflex and antenna for my new Bridgecom repeater. There's no point at all in putting used tires on a new car! agreedhow long is the cable run? Quote Link to comment Share on other sites More sharing options...
JohnE Posted February 26, 2016 Author Report Share Posted February 26, 2016 I'm tuned in. I happen to have the 6dbd Comtelco. Got burned though, didnt do my home work and bought it straight from Comtelco only to find out I could have saved a hondo from one of thier vendors!oh well, hopefully it compares well in your comparison so it takes some of my sting away...LOLI call them directly and did not pay what they showed on their web page. it was actually less than what their vendors sell it for.also just for the record I have one already and have been happy w/results I'm getting. Quote Link to comment Share on other sites More sharing options...
rfmedic Posted March 1, 2016 Report Share Posted March 1, 2016 D*** lairds...nothing but 200watt dummy loads rfmedic 1 Quote Link to comment Share on other sites More sharing options...
JohnE Posted March 16, 2016 Author Report Share Posted March 16, 2016 the new antenna is here and here are some pics of the 3 antennas I will bu using.L-RLaird, Comtelco, RFShttp://i1105.photobucket.com/albums/h358/erscom/antennas/IMG_0226_zpsbicbvuwz.jpgID tags on the antennashttp://i1105.photobucket.com/albums/h358/erscom/antennas/IMG_0229_zpsw7pyn4ro.jpghttp://i1105.photobucket.com/albums/h358/erscom/antennas/IMG_0230_zps0zmcfqwk.jpghttp://i1105.photobucket.com/albums/h358/erscom/antennas/IMG_0231_zpsmolw5drl.jpgfor the record the machine is currently running a Laird like the one in the pics, I just used this one as a reference to the others.hope to put up the Comtelco on Friday weather permitting.one other interesting point on these, the Comtelco is not DC grounded the other 2 are. Quote Link to comment Share on other sites More sharing options...
JohnE Posted March 23, 2016 Author Report Share Posted March 23, 2016 swap 1 made to the Comtelcoas an added side note the VSWR for the Laird was 1.3 and the Comtelco was 1.65. Quote Link to comment Share on other sites More sharing options...
ASRM Posted March 27, 2016 Report Share Posted March 27, 2016 Our shop has a slew of the Laird's (10+ in stock), I am thinking about using one for our new 675 repeater that we hope will go up in a month or 2, after the new tower and my experimental build of a Johnson PPL6000. I have been hearing really good things on the Laird's. Quote Link to comment Share on other sites More sharing options...
mainehazmt Posted March 28, 2016 Report Share Posted March 28, 2016 Send your rejected ones to me. Your worst is prob better than my best lol Btw is there a way besides an antenna analyzer to see if an antenna is good? I have an older business band uhf that I have no clue aboutDon't want to install it and find out it isn't any good Quote Link to comment Share on other sites More sharing options...
n4gix Posted March 29, 2016 Report Share Posted March 29, 2016 Sure! A $3000 spectrum analyzer with tracking generator and a VSWR bridge... Quote Link to comment Share on other sites More sharing options...
coryb27 Posted March 29, 2016 Report Share Posted March 29, 2016 Sure! A $3000 spectrum analyzer with tracking generator and a VSWR bridge... Send your rejected ones to me. Your worst is prob better than my best lol Btw is there a way besides an antenna analyzer to see if an antenna is good? I have an older business band uhf that I have no clue aboutDon't want to install it and find out it isn't any good I would think the cheaper way would be to bolt it to something stable like a metal fence or just stand it up on a mast. Once you find a way to stand it up hook up a radio and an SWR meter and see what you get. How ever you test in be sure it has ample free space and don't get to close to it well keying it up. You may ask around and see if any of your fellow hams have an Anritsu Site Master and if so can you get them to sweep it for you. Corey mainehazmt 1 Quote Link to comment Share on other sites More sharing options...
coryb27 Posted March 29, 2016 Report Share Posted March 29, 2016 swap 1 made to the Comtelcoas an added side note the VSWR for the Laird was 1.3 and the Comtelco was 1.65. John, Ever tried any of the dipoles on your repeater? I run a DB404-B on my base, DB411-B as the TX antenna and a DB413-B as the RX on my commercial UHF DMR system, I am getting ready to upgrade my other commercial site to a Duplexed DB408-B and my GMRS repeater runs a Duplexed DB420-B. I don't have a single bad thing to say about any of them. I do have some choice words about a few of the fiberglass sticks I have used over the years. Corey Logan5 1 Quote Link to comment Share on other sites More sharing options...
jvfreetage Posted March 29, 2016 Report Share Posted March 29, 2016 I would think the cheaper way would be to bolt it to something stable like a metal fence or just stand it up on a mast. Once you find a way to stand it up hook up a radio and an SWR meter and see what you get. How ever you test in be sure it has ample free space and don't get to close to it well keying it up. You may ask around and see if any of your fellow hams have an Anritsu Site Master and if so can you get them to sweep it for you. CoreyI agree with Corey. Just remember, a dummy load has a 1.0:1 SWR. SWR just makes the radio happy. Your field strength meters and just testing the thing is going to give you your best findings. HAPPY HUNTING! James Quote Link to comment Share on other sites More sharing options...
JohnE Posted March 29, 2016 Author Report Share Posted March 29, 2016 Sure! A $3000 spectrum analyzer with tracking generator and a VSWR bridge...I have an Agilent antenna/cable analyzer and a General Dynamics service monitor w/most of the options.this is just a field test for the real world for S's and G's to compare if $$$$$ antenna performs as well as the $$ antenna. Ever tried any of the dipoles on your repeater? I run a DB404-B on my base, DB411-B as the TX antenna and a DB413-B as the RX on my commercial UHF DMR system, I am getting ready to upgrade my other commercial site to a Duplexed DB408-B and my GMRS repeater runs a Duplexed DB420-B. I don't have a single bad thing to say about any of them. I do have some choice words about a few of the fiberglass sticks I have used over the years.I have never cared for exposed dipole arrays as I have had too many water intrusion issues w/them. I had a DB 411 and gave it to one of Rich's buddiesI have had some manufacturing issues w/fiberglass antennas. radomes coming out of the support pipes but those were Irene and Sandy related.http://i1105.photobucket.com/albums/h358/erscom/antenna%20fails/kcc006.jpghttp://i1105.photobucket.com/albums/h358/erscom/antenna%20fails/kcc003.jpg Logan5 1 Quote Link to comment Share on other sites More sharing options...
coryb27 Posted March 30, 2016 Report Share Posted March 30, 2016 So far I have not had any issues with the Andrew / Comscope DB line of dipoles. The DB420-B on my GMRS site is over 10 years old and still works as good as day it was put into service. I have herd others complain about some of the DB knockoffs failing in the field but never any bad words about the real deal dipoles. That is crazy how the antenna separated at the mount, must have been some crazy wind! My issue with past fiberglass was the gelcoat weathering and water soaking into the glass mat causing huge drops in performance. Your would be the first one I have seen sheer off at the mounting tube. Whats the broadcast antenna stack in the background? Quote Link to comment Share on other sites More sharing options...
JohnE Posted March 30, 2016 Author Report Share Posted March 30, 2016 college FM broadcast. Quote Link to comment Share on other sites More sharing options...
n4gix Posted March 30, 2016 Report Share Posted March 30, 2016 Irene's and Sandy's winds surely must have far exceeded the wind-loading design for those fiberglass antennas... Quote Link to comment Share on other sites More sharing options...
zap Posted March 30, 2016 Report Share Posted March 30, 2016 RFI builds a sweet (fully welded) exposed dipole array that's worth checking out if you have some money to burn. DB's water intrusion issues were mostly settled by 2005. Know of a 224 suffering from it currently. Sent from my SM-T350 using Tapatalk Quote Link to comment Share on other sites More sharing options...
mainehazmt Posted March 30, 2016 Report Share Posted March 30, 2016 I would think the cheaper way would be to bolt it to something stable like a metal fence or just stand it up on a mast. Once you find a way to stand it up hook up a radio and an SWR meter and see what you get. How ever you test in be sure it has ample free space and don't get to close to it well keying it up. You may ask around and see if any of your fellow hams have an Anritsu Site Master and if so can you get them to sweep it for you. Coreyhave to wait till the snow is gone lol. Ps sorry for the hijack. John Quote Link to comment Share on other sites More sharing options...
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