7/800mhz antenna combiner question / help

[boatanchors]

I just recently picked up a DMS YA76014 760-780 MHz Yagi with 14.0dBi gain, I just installed it on the tower which is a 50ft tower next to the house with a rotor inside the tower, I have the ant at 53 feet with only 75 foot LMR-400, the antenna is working fine, but here is my problem, i am trying to recieve another Ohio Marcs site which is just over 27 miles away line of site but its main control freq is 853.8375.. So i was thinking of getting an 800 mhz yagi to install on the tower along with the 760mhz ant and I am sure i am going to need to get a combiner of some sort to combine the two antenna but not sure which type or even whom may sell them.. I can hear the site i am trying to receive but the signal is'nt strong enough for the scanner to lock onto the control channel.. So my question is should I just stick with the 760 mhz yagi i have up and go with a preamp or get a 800mhz yagi and get a combiner and hook the to together.. I would sure appreciate any help and advice on this.. Thanks for everyones time

Here is the DMS yagi i bought which does work very well for the 700mhz
http://www.ebay.com/itm/Model-YA760...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

 

[prcguy]

I have not seen a 700/800MHz combiner but that doesn't mean they don't exist. That would probably be a commercial item costing a lot of $$.

The gain on a Yagi usually falls off sharply above a point and its hard to say how well your 700MHz Yagi might be working at 853MHz but it probably has some gain there. If it still has some usable gain at 853MHz then another Yagi for 850Mhz may not do much for you.

If all the stations you want to hear are in the same general direction and you still want to get a Yagi for the higher freqs I would look for a broad band version that covers the entire range. Or find a commercial vertical omni with 10dBd gain across the entire range.
prcguy

I just recently picked up a DMS YA76014 760-780 MHz Yagi with 14.0dBi gain, I just installed it on the tower which is a 50ft tower next to the house with a rotor inside the tower, I have the ant at 53 feet with only 75 foot LMR-400, the antenna is working fine, but here is my problem, i am trying to recieve another Ohio Marcs site which is just over 27 miles away line of site but its main control freq is 853.8375.. So i was thinking of getting an 800 mhz yagi to install on the tower along with the 760mhz ant and I am sure i am going to need to get a combiner of some sort to combine the two antenna but not sure which type or even whom may sell them.. I can hear the site i am trying to receive but the signal is'nt strong enough for the scanner to lock onto the control channel.. So my question is should I just stick with the 760 mhz yagi i have up and go with a preamp or get a 800mhz yagi and get a combiner and hook the to together.. I would sure appreciate any help and advice on this.. Thanks for everyones time

Here is the DMS yagi i bought which does work very well for the 700mhz
Model YA76014 DMS Wireless 760-780 MHz Yagi 14.0dBi Gain Directional Antenna | eBay

 

[boatanchors]

I kind of figured the same thing with the commercial combiner costing a lot $$$... The yagi i have works great in the 700mhz but it sure does fall off very quickly. On one site which is about 12 air miles away the main control channel is in the 700 mhz range and I get it full scale on the s meter but when they talk the site jumps into the 850mhz range at times and it goes from full scale to about S 4 to S 5 on the signal from full scale so yes it does drop off a lot.. I can here the site that i am wanting to recieve which there control channel is 853 mhz but I get no signal on it at all so no chance of the receiver locking on to the control channel.. No more than a LNA cost i might try that of get one of the 850mhz cell yagi and just add it to the tower as well and just switch antennas when i want to listen to that site.. Thank you for taking the time to respond and your input....

 

[Ubbe]

Yagis drop off in gain considerable when you try to use them above their frequency range, but going lower in frequency will have a more equal ratio between gain drop and frequency.

So I suggest you get, or build, a yagi that handles the highest frequencies you would like to receive with gain and the lower ones will still have a healty gain.

I use tv antennas designed for 470-750MHz and they work fine for scanner use in the 400-470MHz range. I once had a tv antenna for my television set that covered up to 600MHz and a new channel was added in the 700MHz and there where absolutly no signal on that channel. I removed all the director elements and when I only had the dipole left I finally got a signal.

If you google tv antennas gain curves you'll notice that the gain increases from very low frequencies, outside the specified range, and goes steady up to the max frequency where the gain drops almost straight down to zero.

/Ubbe

 

[cpetraglia]

I have used a Stridsberg broadband multicoupler for this before with good results. You can get a broadband (5-1000 Mhz) and just reverse the antenna/scanner connections. It becomes a combiner with good isolation between antennas. There not cheap, but some of the best in the business. I have also used an HDTV antenna with a rotor and real good results. Be sure to read the specs and make sure your frequency range is there and mount it vertically.

 

[JamesO]

So my question is should I just stick with the 760 mhz yagi i have up and go with a preamp or get a 800mhz yagi and get a combiner and hook the to together.. I would sure appreciate any help and advice on this.. Thanks for everyones time

As for a decent very low noise LNA, this is what I am using mounted right at the base of my antenna with DC fed up the coax at the moment. It works very well for me in a very harsh RF environment. I went through about 6 different FM Broadcast band notch filters before I found something that worked for my set up.

I have a few VERY high level FM stations between 3-5 miles from where I live and the FM level from one station was really a problem.

Mini-Circuits LNA and Bias-T along with a GPIO Labs 85 dB FM Broadcast band notch filter.

https://www.dropbox.com/sh/hmvxvtev71z09z8/AACpt0RSsfk5BI5T2JD0WOfNa?dl=0

While some may say this does not work, it is what I have been using for about a year now with outstanding results. I am located in a very demanding and harsh RF environment as well as located under a flight path for a major national airport. The FM stations are really problem even though I am not far from many of the Over The Air TV stations and have a number of cell phone sites within 1 mile of my antenna.

If you do not need the Bias-T or choose to use a cheaper CATV/SATV version, you are looking at around $100 for the LNA and FM notch filter, plus any connectors. Maybe around $125-$150 depending on what your final configuration might be if you need to mount this in a PVC or plastic enclosure on the tower.

And this final configuration was after trying a lot of different amplifiers, probably around 6-8, in addition to about 6 FM notch filters so I have spent a lot of time and money finding a solution that works and will likely work for many configurations.

 

[boatanchors]

Thank prcguy cpetraglia & Ubbe I really appreciate your advice and input.. I think I am going to look into just getting a 850mhz Yagi that has some decent gain to it and just add it to the tower with the 760mhz antenna and I can just switch antenna's when i want to listen to the other site.. I really appreciate everyone's knowledge and experience on this.. Thanks so much for the help

 

[boatanchors]

Ok JamesO I'll look into to that as well I appreciate the help.. Any and all help is much appreciated.. Thanks

 

[JamesO]

Here is some more info - https://forums.radioreference.com/s...mp-10-off-december-other-useful-rx-items.html

 

[boatanchors]

Ok will do Thank You JamesO

 

[JamesO]

Not really knowing everything you are tying to accomplish, while the 700 MHz was cheap, it may not be the ideal antenna for you in the long run. You might be better off with an Omni antenna an the LNA configuration and it may match or even outperform the 700 MHz yagi for your monitoring requirements. This would also give you a much wider overall antenna system.

Unless you are tying to deal with some very specific receive problem, I would try an Omni with a LNA set up.

 

[boatanchors]

7/800mhz Ant

Well JamesO everything around me for my county is a Breeze, I have one of the main sites only a mile from my house so a wet noodle works great for it LoL and the other countys around me i get with a breeze no problem... Its just those sites that i am wanting they are a few towns over, the main one i want it 27.6 miles Line of Site, I can hear it but the signal is'nt there enough to be able to lock on.. I am going to home brew a 850mhz 9 element yagi and give it a try with LMR400 on it to the shack here which my tower is mounted out side my shack window and my shack is on the second floor so i dont have one run that is any lomger than 70 ft.. Any way will let you know how i come out on the 850mhz Homebrew yagi... Will keep you advised as to its dids and didnts.. lol