You're probably right. I sure am testing the HOA's patients. Though I don't intend to spend a lot of money. I have other things I have to take care of first (I'm 23). Lol. Though if temptation gets me I'll probably get the other antennas.
Best antenna?
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Ameritron RCS 8V x HF to VHF UHF Remote Coax Switch | eBay
Could add one of these bad boys and have 5 antennas hooked up to this.
Could add one of these bad boys and have 5 antennas hooked up to this.
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Mounting a vhf/uhf antenna that close to your scanner discone is a recipe for disaster. The TMD710 is capable of transmitting 100 watts rf. Within that close proximity you will surely fry the front ends of any receivers connected to your discone. To achieve 60db of isolation at vhf frequencies you would need to seperate the two antennas vertically at least 50 feet. At uhf frequencies vertical seperation would be at least 20 feet. (source: repeater-builder.com/antenna/separation.html)
I suppose this wouldn't be a forum if there weren't different answers. One guy says it will work and another saying it won't.
50' vertical separation isn't going to happen. I don't have that option. There would have to be some alternative way. Do remember that I live under an HOA and I'm quite limited to what I can do. If there's an accessory to integrate into the antenna line that would fix that problem that would be my only option. I'm not disregarding advice but somehow the current plan has to work if possible. I'm very limited in what can be done.
50' vertical separation isn't going to happen. I don't have that option. There would have to be some alternative way. Do remember that I live under an HOA and I'm quite limited to what I can do. If there's an accessory to integrate into the antenna line that would fix that problem that would be my only option. I'm not disregarding advice but somehow the current plan has to work if possible. I'm very limited in what can be done.
Ive done lots of close proximity transmitting for the last 20 yrs or so and have never even toasted a cheap scanner...
Look at cop cars etc. they have many antennas mounted really close and don't have any radio toast issues....
Look at cop cars etc. they have many antennas mounted really close and don't have any radio toast issues....
I have a friend who is a seasoned ham. I asked him about it. He mentioned that 100 watts isn't necessary when the antenna is high up as I am going to have it. 10-20 watts should be typical power to reach repeaters which are abundant in this area. Power shouldn't exceed 50 watts max.
According to Kenwood, the TM-D710 is rated for 50 watts output on VHF or UHF.
mmckenna
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Right, and they are usually a 1/4 wave length apart with 1/4 wave or similar antennas. Going with higher gain antennas is going to increase ERP.
I've seen it happen on poorly filtered receivers.
It's an easy thing to avoid, so it isn't necessary to take the risk. Also, increasing separation will help lower the desensitization of the receiver when the other antenna is transmitting.
Your milage may vary.
This is pretty close to an old wives tale...
mmckenna
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I understand your skepticism. I've seen this issue happen before. We had two trucks in the family with identical setups, An Icom F-420 35 watt UHF radio for amateur/GMRS and work stuff. A Yaseu 2 meter mobile. The Yaseu's both had their front ends fail on the receivers. Poor filtering on the Yaseu's. The Icom's didn't have any issues with the 2 meter transceivers.
Better filtering on the receiver side will help reduce this, but separating the antennas farther apart helps too.
You are welcome to install however you want. I've just seen this issue happen, and have seen properly installed systems not have this issue.
Pretty easy to look up industry suggestions on antenna spacing. May not be a concern for amateur radio operators, CB'ers and scanner listeners, but when installing gear professionally, it's a good idea to do it right the first time.
Increasing antennas separation will also reduce receiver desensitization when one is transmitting and the other is receiving.
Same reason repeaters are set up this way. Either duplexers are used to control input to the receiver, and/or lots of antenna separation.
Public safety vehicles would only have 1 antenna each if this was a real issue....
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mmckenna
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I don't understand what you are saying.
Public safety vehicles will have as many antennas as they need. Just take a look at a California Highway Patrol vehicle. They'll have 4 or more antennas on them. Spacing is key, also they tend to use high end radios that usually have really good receiver filtering, not the low end stuff that scanners or amateur radios have.
Our PD cars at work have an 800MHz antenna mounted on the roof top, behind the light bar and a VHF whip on the trunk. The separation is plenty to not be an issue. VHF radio is running about 80 watts. 800MHz is running about 15 watts.
We would not have stuck the antennas side by side with only a few inches between them. We spread them out as much as we can.
With good filtering, like between a low band radio and a uhf radio, the issue is lessened by having good filtering in the radio to reduce out of band RF. That helps reduce any crap coming out of the transmitter and will reduce some incoming RF if it's outside the passband.
The trouble with a scanner is they have a very broad band receiver, so filtering won't work. The receivers are pretty wide open to overloading, desensitization, and even damage if the transmitting antenna is too close.
With a CB, it usually isn't an issue since they are often running well under 4 watts. Figure in feed line loss and if you are getting 2 watts out of the antenna, you are doing pretty good. Now add in feed line losses between the scanner antenna and the scanner, and the amount of coupled power getting back into the scanner is even further reduced.
When you are running more power with lower loss feed line, this can be a bigger issue. Especially amateur radio operators or public safety radios running 50 - 100 watts.
If you are referring to the 4 antennas arranged in a square that you'll see on some police cars, those are receive antennas for LoJack, and not transmitting antennas.
But hey, you do whatever you want. I'm just passing on info the OP so he doesn't create any issues for himself.
The bottom line is that its not an issue....
mmckenna
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OK. If you say so.
These 2 guys must have lots of dead radios lol
http://www.g0hwc.com/images/radio-car1.jpg
http://www.hackpittsburgh.com/wp-content/uploads/2010/05/AntennaCar.jpg
http://www.g0hwc.com/images/radio-car1.jpg
http://www.hackpittsburgh.com/wp-content/uploads/2010/05/AntennaCar.jpg
I'll add in another vote for putting more distance between your antennas.
mmckenna has explained it well enough.
If you can, maximize vertical and horizontal separation between your antennas.
mmckenna has explained it well enough.
If you can, maximize vertical and horizontal separation between your antennas.
If you can find any... Ill fix em
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