antenna duplexer or not ???

[okla-lawman]

aWell I finally broke down and bought new antennas for my scanner.
I lucked out and got a tri band comet loband 2.1 db/vhf 3.5/uhf 5.0 db
gain (on ebay for $36). I also have an antenna specialists 5 db gain 800 antenna. I had originally planned on a simple t arrangement in the trunk with a single cable coming foward to the pre amp. I have heard I may loose considerable signal stength doing this. I have checked for a duplexer which would handle 45 to 460mhz on one side and 800 on the other without sucess. Any ideas?? Thanks




k5mar it is all your fault...I kept reading your posts about low band and decided I might be missing something :lol:

 

[Pro-95]

Any ideas?? Thanks

Part of my next bonus check will pay for a TRIPLEXER for my J-poles. There is noticable difference in reception range and quality using a "T". From what has been described, you loose 1/2 signal with a "T" 1/2 again if you split it again before you know it you have no gain or signal. I've consdiered an Antenna Switch but those are about the same bucks and since I'm not TX'ing the thoughtless triplexer makes more sense.

 

[okla-lawman]

Pro 95 check ebay I saw some triplexers for under $50. The problem is
though they usually are lowband/vhf and then uhf 400. I would need one that would cover 50 to 460 mhz on one side and then 800 on the other.
Otherwise I would have to split the signal using a duplexer to feed into a triplexer. Again signal loss......

 

[K5MAR]

aWell I finally broke down and bought new antennas for my scanner.
I lucked out and got a tri band comet loband 2.1 db/vhf 3.5/uhf 5.0 db
gain (on ebay for $36). I also have an antenna specialists 5 db gain 800 antenna. I had originally planned on a simple t arrangement in the trunk with a single cable coming foward to the pre amp. I have heard I may loose considerable signal stength doing this. I have checked for a duplexer which would handle 45 to 460mhz on one side and 800 on the other without sucess. Any ideas?? Thanks


k5mar it is all your fault...I kept reading your posts about low band and decided I might be missing something :lol:

You are!

Unfortunately, I don't know of any duplexers (diplexer, actually) that will combine the 800 MHz. band with the VHF/UHF bands. Yes. it is likely you will lose some signal strength using the "T", but on the other hand, being in the Tulsa area, this may not be a problem. My suggestion, try the Comet by itself. You may fine you have an acceptable signal on the 800 MHz band without the A/S antenna. If nothing else, it will give you a basis of comparison when you do try the "T". Another suggestion would be to get a signal splitter rated to 900 MHx. Generally these are used in Sat. TV/over-the-air combined setups. Although these are 75 ohm with F connectors, they should work fine. Just bring your antennas into the two outputs, then connect your scanner to the input. Watch out for the cable TV splitters, these are generally only rated to 500 MHz.

BTW, last Saturday I was listening to an Ocean unit on 44.70 MHz working I-35 around mile 162, he was clocking speeds as high as 105 MPH! Sounds like some potential Darwin Award winners, eventually!

Mark S.

 

[okla-lawman]

I tried not running an 800 mhz antenna with my current set up. It is an Anli vhf/uhf and 800 performance is not stellar. You can pick up but not with any consistency. I miss alot that I pick up on my radio. I can only pick up ba/bix/gpool if in their cities. I generally try to monitor around any area I am working and would like a little more notice.

 

[K5MAR]

In that case, I'd recommend something like this:
http://www.radioshack.com/product.a...e=CTLG_003_001_003_001&product_id=15-1234 I believe it goes to 900 MHz, if not, there are others available that do. Here are a couple of more possibilities from the RS website:
http://www.radioshack.com/product.a...e=CTLG_003_008_003_000&product_id=16-2586 (A bit pricey)
http://www.radioshack.com/product.a...e=CTLG_003_008_003_000&product_id=16-2578 (Think I'd go with this one, myself.)

Of course, you can try using just a "Tee" and see what it does, but I'm afraid your losses would be higher than you want. But if you already have the "Tee", give it a shot!

Mark S.

 

[N4DES]

How about something like this:

http://www.rfwiz.com/AustinAntenna/AustinAntennaTriplexers.htm

 

[K5MAR]

My first thought was COOL!, but then I saw the price.
$153
Ouch!

Then there's this line on the order site:

NOTE: Multiplexers are "Built on Order"...allow minimum of 4-6 weeks to ship.
**PLEASE NOTE: MULTIPLEXERS ARE CURRENTLY UNAVAILABLE FROM AUSTIN ANTENNA**

Mark S.

 

[Pro-95]

My first thought was COOL!, but then I saw the price. $153 Ouch!

Yep. Pretty much the same for remote relay operated antenna switch. :shock:

Although as far as a remote switch.....

Hmm, a couple-3-4 relays switching both ground and positive for isolation, one lead coming from relay box output to lead in to house. Two -2-pair wires from the switch to send positive to the antenna base use ground at antenna. Two project boxes, a multi position DP high isolation rotary switch or a couple-3-4 of SPST's risking turning on all the relays, 4-5 panel mount So-239's and a small power supply at the switch in the house to inject switched power to the antenna base. In theory it seems simple but I'm sure there are other issues to contend with such as keeping feedback from returning to one of the other non-switched relays. Keeping 50-Ohm impedance through the relays and switchbox wiring. Weather proofing the box at the antenna base and lightning protection.

 

[Pro-95]

BTW, these guys seem to be a bit more reasonable, pricewise.

>>>> RFPARTS.COM <<<<

Still...... I could have some fun building the switch box.

 

[Pro-95]

So keeping 50-Ohms isn't quite that important on really short runs??? :?: :?: Feedback isn't an issue???? :?: :?:

:shock: I smell a little project coming on. :wink:

 

[Thayne]

IMHO, I don't think I would try to chase anything higher than audio thru that relay-laden contraption, but good luck anyway

 

[N_Jay]

So keeping 50-Ohms isn't quite that important on really short runs??? :?: :?: Feedback isn't an issue???? :?: :?:

:shock: I smell a little project coming on. :wink:

Keeping 50 Ohms is unimportant on short runs.

BUT!!!!

Short is "Less than 1/8 a wavelength"! So at 800 even short runs are an issue.

What is going to feedback?????

 

[Pro-95]

What is going to feedback?????

Probably my misuse of the term but when signal goes back into the other non-switched relays but it seems with a little cap and a resistor this can be stopped.

 

[N4DES]

My first thought was COOL!, but then I saw the price.
$153
Ouch!

Then there's this line on the order site:

NOTE: Multiplexers are "Built on Order"...allow minimum of 4-6 weeks to ship.
**PLEASE NOTE: MULTIPLEXERS ARE CURRENTLY UNAVAILABLE FROM AUSTIN ANTENNA**

Mark S.

Yeah I know they are expensive, but I have to say that the Austin products is one of the best in the industry. I have one of the multi-band mobile antennas and it outperforms any Diamond or Comet antenna I have ever used.

I had an opportunity to demo the tri-plexer a numer of years back and it worked as advertised. I didn't have anything else to compare side by side, but they do make an awesome product even if you have to custom order it.

Anyway I was just trying to offer info to the origional query and didn't know what his budget was like.

Have a nice weekend!

 

[okla-lawman]

I had thought about an antenna switch but want something like the guy says on tv set it and forget it. I already have a ton of things to monitor
and dont have time to worry about switches.

I have looked at the Austin specter antenna. If this set up does not work
like I watn it I may try it. I have their condor on my hand held. K5mar
speaks highly of it.

I thiink I am going to just try a t fitting, I spoke with the guy over at electroninc systems yesterday and he is going to help me next week
to redo the connectors, shorten the cables etc to keep cable runs to a minimum and number of adapters...etc. I am hoping this will work.

 

[okla-lawman]

I had thought about an antenna switch but want something like the guy says on tv set it and forget it. I already have a ton of things to monitor
and dont have time to worry about switches.

I have looked at the Austin specter antenna. If this set up does not work
like I watn it I may try it. I have their condor on my hand held. K5mar
speaks highly of it.

I thiink I am going to just try a t fitting, I spoke with the guy over at electroninc systems yesterday and he is going to help me next week
to redo the connectors, shorten the cables etc to keep cable runs to a minimum and number of adapters...etc. I am hoping this will work.

 

[K5MAR]

My first thought was COOL!, but then I saw the price.
$153
Ouch!

Then there's this line on the order site:

NOTE: Multiplexers are "Built on Order"...allow minimum of 4-6 weeks to ship.
**PLEASE NOTE: MULTIPLEXERS ARE CURRENTLY UNAVAILABLE FROM AUSTIN ANTENNA**

Mark S.

Yeah I know they are expensive, but I have to say that the Austin products is one of the best in the industry. I have one of the multi-band mobile antennas and it outperforms any Diamond or Comet antenna I have ever used.

I had an opportunity to demo the tri-plexer a numer of years back and it worked as advertised. I didn't have anything else to compare side by side, but they do make an awesome product even if you have to custom order it.

Anyway I was just trying to offer info to the origional query and didn't know what his budget was like.

Have a nice weekend!

Not attacking your information or the offering of it. My thought was that most people (a generalization, I know) probably wouldn't be willing to spend that much for a triplexer. Also, as I pointed out, the website says the multiplexers are currently unavailable, so the whole point is moot.

In this case, OK Law's stated desire is to enhance his VHF-low reception, and the triplexer's low end is 144 MHz. Not a good sign.

I have a high respect for Austin Antenna products and use the Austin Spectra antenna on my truck. But most scannists complain about it's $80+ price tag. Me, I do what I have to do to get the reception I need.

My weekend looks pretty good, today and tomorrow's highs are supposed to be in the high seventies! This is late July in Oklahome?

Have a good,
Mark S.

 

[okla-lawman]

comet makes a vhf/uhf/800 triplexer too. But then I think you would have to spli the signal from the antenna usind a duplexer and feed it into a triplexer to feed it to the pre amp....that is a lot of money.

I hope you all are enjoying your weekend....I called in to work. Have to go
on duty at noon. Good weather for hunting though.

 

[N_Jay]

What is going to feedback?????

Probably my misuse of the term but when signal goes back into the other non-switched relays but it seems with a little cap and a resistor this can be stopped.

The Cap and Diode (not resister) are on the coil side, not the RF side.

You will not ave enough RF power to worry about on any contact.