How to find TX frequency?

[martyrs]

Hello all Radio Reference folks,
I am new to radio hobby and i'll become a licensed amateur very soon, i hope!
Meanwhile, i am playing with my equipments that i have.
- Baofeng UV-5R
- Uniden Bearcat BC75XLT

However, i am very confused about Transmission (TX) thing.
I have no problem with listening frequencies at all. Uniden does a great job on scanning.

Let me explain the whole thing (i also draw an image to explain)

Assume that i have found a frequency 450.800 MHz on my Uniden scanner and there are many stations on that frequency. And all stations are from very large radius. So its obvious that it's a radio repeater (450.800 MHz) And there is no CTCSS or DCS, so i am able to monitor freq by both Uniden and Baofeng without any extra setting.

So, my question is that how to find where all stations Transmitting (TX) to?.
I mean, how to find TX frequency for this radio repeater?

And is that possible to monitor the "INPUT" leg of radio repeater?
I am very confused about this.

Basicly, i am able to listen repeater but i can't understand how to and where to transmit to repeater. Because i don't have exact TX info for this frequency. (on web, databases or anything)

May someone help me on that?
Any piece of info would be great!

 

[captclint]

A simple answer for your example is: TX is always 5Mhz higher than the RX on the UHF band, so, TX would be 455.800. There are other similar relationships for 800Mhz, but not for VHF. Now if you are asking about HAM bands, I don't know those relationships off hand. I would hope you know the restrictions on transmitting into anything except an amateur repeater..

 

[jonwienke]

If you don't know the freq and tone/code for the input side of the repeater, you probably have no business transmitting through it. There are several online repeater databases, including one on this site. Spend a few minutes on Google, and listen before jumping in on a repeater. Not all of them are open to the public.

 

[teufler]

ham vhf usually 600 up or 600 down. 146.995 and down, transmitter is down 600. say 146,67, input is 146.07. 147.000 and up to 147.997, transmit up 600. 147.30, 147.90 input. The input is what the users transmit on to activate the repeater. Now beyound ham bands, vhf input is all over the place. Noset pattern. 800 mhz systems are down 45 mhz from their output. Other than listen to the inputs to see if a unit is around you, I don't see much accomplished by listen to inputs on 800 mhz. N o ham radios cover the 800 mhz bands but scanner do. If you have the inputs programmed in, you will see if a unit is anywhere around you. About 5 miles or less. The clearer, the closer. Some of the ham radios have automatic input checking, a symbol will start blinking when a station, working a repeater, is in range to go simplex. Sort of nice when you do not want your signal going out to the world. By monitoring the inputs, you can determine what power to use also. Most of the ham radios will scan for the sub tone or dcs codes.

 

[SCPD]

If you don't know the freq and tone/code for the input side of the repeater, you probably have no business transmitting through it. There are several online repeater databases, including one on this site. Spend a few minutes on Google, and listen before jumping in on a repeater. Not all of them are open to the public.

There's always one.

 

[nd5y]

The OP doesn't have a profile location. We don't even know if he is in the United States or not. We need to know the exact system frequency and location in order to properly help.

The OP's frequency 450.800 is a broadcast auxilliary service frequency in the US. They don't always have a 5.0 MHz offset.

Here is a wiki article for the standard repeater offsets in various bands in the US. Offset - The RadioReference Wiki

 

[Ed_Seedhouse]

The frequency you hear a signal on is always the frequency the signal is being transmitted on. If you hear a repeater at 146.84 then it is transmitting on 146.84. A repeater will generally be listening on another frequency so if you want to talk to it your transmitter should transmit on the frequency the repeater is listening to.

For example repeater at 146.840 will be listening 600khz lower, i.e. at 146.24.

So your transceiver must listen on 146.84 and transmit on 146.24.

Contra-wise the repeater will transmit on 146.84 and listen on 146.24.

With a repeater your transceiver must transmit on the frequency the repeater listens to, and listen on the frequency the repeater transmits on.

So to configure your transceiver to work with the repeater you need to know the repeater transmit frequency, it's listening offset, and the direction of the offset. And since most repeaters will not listen to your radio unless it transmits the right tone on the audio you must know the frequency of the "sub-audible" tone it wants to hear from your radio.

So, repeater transmit frequency, offset, direction of offset, and (usually) frequency of the tone required, is what you need to program your radio for in order to successfully use a repeater.

If you are transmitting direct radio to radio (simplex), all you need to know is the frequency. You listen and transmit on the same frequency.

 

[SCPD]

Go by them and use close call that will give you transmit frequency for sure.
But I agree its + 5 MHZ for transmit from the receive.

 

[robertmac]

And the transmitter transmitting into the repeater would have to be much closer to you for you to hear that. Repeaters are generally much higher up so their range is much greater than the imput transmitter. I would say get your ham license first and a lot of this will be explained. Until you have a ham license or an authorized license to transmit on the frequency, just listen to the repeater. The input will not give you anything that can be heard on the repeater.

 

[martyrs]

Hello everyone,
Thanks for great info and help.
I am totally aware of the legal regulations in my area (Turkey)
And my intention is not transmitting to a frequency which i am not allowed to.
I have configured my Baofeng for offset/shift for local club's Amateur Repeater frequency on my area and it works. (Thanks to club, they allowed me to test and i am able to talk with other amateurs without any problems!)
So i am kinda used to these terms. And i don't have problem on configuring my radio at all.

However, i did more research and it's correct that TX must be 455.800 (for standarts)
But when i scan with my Uniden and monitoring 455.800 on my Baofeng radio, there's no activity.
As i understood, TX is on a different frequency. And i think it differs because +5MHz is USA standart and configuration is different here in Turkey.

And after more research, i am ended up with these options
- Find TX/RX/tone details on web
- Ask to someone

However, both options are not available in my case.
If my radio physically near to Radio Repeater, so i can monitor the repeater's INPUT, is that right? So that means i can find TX frequency.

@ks2ool: Do you mean Close Call option in Uniden?

Again, i am not intended to transmitting on a frequency by any legal/illegal purpose. I can understand the "get a license" approach but i would like to educate myself about all theorical and technical topics.

Thank you all!

 

[Spitfire8520]

As i understood, TX is on a different frequency. And i think it differs because +5MHz is USA standart and configuration is different here in Turkey.

And after more research, i am ended up with these options
- Find TX/RX/tone details on web
- Ask to someone

Yes, the +5 MHz is a suggestion based on the assumption that you were talking about something located in the US. Otherwise, a lot of what people do (in the US) is look up frequency licensing that is made public by the FCC. Apparently the equivalent organization would be Bilgi Teknolojileri ve. I don't know if they operate in the same way and allow for this information to be made publicly available.

However, both options are not available in my case.
If my radio physically near to Radio Repeater, so i can monitor the repeater's INPUT, is that right? So that means i can find TX frequency.

@ks2ool: Do you mean Close Call option in Uniden?

Maybe. It's more of if your radio is physically near the place of which the radios are being used. The closer you are to the radios being used, then the more likely you are going to pick up on the strength of their signals.

The close call option on the Uniden basically does a quick search along a band of frequencies and attempts to locate a strong signal nearby. It's generally useful for situations like this one where you know a band of frequency that it might be on, but don't know what it is exactly. You basically turn on the close call option, wait for the user radio to transmit, and it should make an attempt to find and stop on the frequency that the radio is using.

 

[jonwienke]

There's no reason to have your scanner listen to the input side of the repeater. The repeater output will have exactly the same traffic, but a much better signal. If you want to talk on the repeater, you should be able to get the input frequency and tone from your local amateur radio club. Doing a Google search for repeater frequencies in your area should also get you what you're looking for.

 

[martyrs]

@Spitfire8520: I got the whole idea now, thanks! And the local organization provides tiny info about band planning but still useful for research

@jonwienke: Still working on finding frequency/tone for TX.

Thank you all.

 

[Ed_Seedhouse]

And the transmitter transmitting into the repeater would have to be much closer to you for you to hear that. Repeaters are generally much higher up so their range is much greater than the imput transmitter.

That may or may not be true depending on the location at which you are receiving. Just for example if you are on the mountaintop next to the repeater antenna you'll probably hear better on the input frequency because repeater antenna rebroadcasting the signal will likely desensitize your receiver. I am on a fair sized hill so I can usually hear most signals on the input. But this is, admittedly, a bit of a nit-pick.

 

[n4yek]

There's no reason to have your scanner listen to the input side of the repeater.

Not true, a reason to monitor it is for interference purposes. You can get into the general area of someone jamming the frequency by monitoring the input.
Maybe you only want your scanner to monitor for things happening that are very close to you or in your neighborhood, then you would want to monitor the input frequency as then you would know they are close to you without hearing all the other traffic. Then you can switch over to the repeater and listen to what is happening in your area. Once it is over, go back to the input.
Not everyone wants to hear every little thing happening, just what is happening around them.

 

[jonwienke]

If he's not even licensed to transmit yet, I rather doubt he'll be foxhunting jammers for a while...

crawl, walk, then run.

 

[martyrs]

Hello all,
After more search, Turkey National Band Plan says "at least +5MHz seperation" which is told on this topic.
So i have started to monitor the frequency 455.800 from different places and finally i got activity. However, there was no sound or voice. Only some noises. Squelch was set to 3. I think i found the INPUT but i wasn't close enough to monitor a proper transmission.
Anyway, it looks like +5 MHz is same here in Turkey.
My other question was about finding transmitting tone.
I know 450.800/455.800 uses CTCSS on transmitting. Is there any way to pick up the CTCSS tone?

By the way, proper configuration must be this way, is that right?
RX: 450.800
TX: 455.800
Shift: +
Offset: 5MHz (means 455.800)
RX CTCSS: None
TX CTCSS: ???

Thank you all.

 

[SCPD]

ref: @k2ool: Do you mean Close Call option in Uniden? A: Yes,and its fast too.

UK is 1.6 MHZ offset did you try that??

 

[n4yek]

If he's not even licensed to transmit yet, I rather doubt he'll be foxhunting jammers for a while...

crawl, walk, then run.

What's that have to do with listening? He just asked where they transmit, he didn't say he wanted it to transmit. He stated if it was possible to monitor the input, the answer is yes.

 

[martyrs]

Hello,
As i stated before, i am not intended to transmit to frequency.
And my question would be same if i am licensed or not.
I am trying to understand the idea.
Thanks.