TKR-750 and Scan

[car5le]

I'm new to the TKR-750/850 repeaters. I've been making good progress understanding programming issues, especially after discovering that there is a Version 1 and Version 2 of these repeaters. One issue I have is with SCAN. I'm looking for some clarification for the scan feature on these repeaters.

If I program multiple repeater channels into the TKR-750 and then turn SCAN on via a PF button:

1. Will the repeater scan all of the programmed channels, and then stop scan on the channel it receives and act as as a repeater for that channel?

2. If it will stop on the received channel and act as a repeater for that channel, will it then resume scan and stop on other channels as received and act on as a repeater on those channels?

3. Or is the scan feature only for use when the repeater is also being used as a base station?

Thanks for any help!

 

[buddrousa]

The only way the repeater will work correct in scan is.
1 ALL CHANNELS ARE THE SAME RX TX AND YOU USE DIFFERENT TONES
465.1500 127.3 460.1500 127.3
465.1500 203.5 460.1500 203.5
465.1500 123.0 460.1500 123.0

 

[mmckenna]

Curious why you'd want a repeater to scan?

You'd have to keep the frequencies pretty closely spaced or your duplexer is going to give you issues.

 

[n7maq-1]

If you are using a single antenna with a duplexer then your channels would need to be the same freq. If that is the case then just use multi-table on a single channel.

If you have a dual antenna system and different RF freqs then you will need to scan but depending on the amount of traffic your results may be less than favorable.

 

[car5le]

Thanks for all the info here folks!

I am familiar and have used the Multi-Table, but I'm looking for an option to scan two separate receive channels. One channel the receive frequency would be different, but still within the "tolerances" of the current duplexer tune. And I'm only talking two channels to scan. I was just curious if the radio was in scan would it lock onto and repeat the channel that came up and would then go back into regular scan.

Our radio traffic is minimal at best where we are - three VFD's in one dispatch. Our dispatch comes from a simplex base station, but our VFD put in a repeater (before I came into the picture) because the coverage from the simplex dispatch in our district is not good. The hope was dispatch would used the new repeater to dispatch. However, dispatch is very "reluctant to change" how they dispatch.

To resolve the issue I've been trying to link the simplex dispatch and repeater. I've done this many times in the past with great success on other systems, but this system is giving me one headache after another and I simply cannot get it to work right. Fix one thing, two more fail...

Another option a Kenwood tech friend of mine mentioned was attaching a controller to the repeater and a mobile on the other side of the controller. Still in discussions on this option...

I'm just looking for simple options that won't break the bank...

 

[car5le]

Well all, It appears I answered my own question. The TKR-750 will not scan if the OPE MODE is selected to Repeat. It will if it is set in Duplex or Simplex mode.

Back to the drawing board...

 

[kayn1n32008]

Thanks for all the info here folks!

I am familiar and have used the Multi-Table, but I'm looking for an option to scan two separate receive channels. One channel the receive frequency would be different, but still within the "tolerances" of the current duplexer tune. And I'm only talking two channels to scan. I was just curious if the radio was in scan would it lock onto and repeat the channel that came up and would then go back into regular scan.

Our radio traffic is minimal at best where we are - three VFD's in one dispatch. Our dispatch comes from a simplex base station, but our VFD put in a repeater (before I came into the picture) because the coverage from the simplex dispatch in our district is not good. The hope was dispatch would used the new repeater to dispatch. However, dispatch is very "reluctant to change" how they dispatch.

To resolve the issue I've been trying to link the simplex dispatch and repeater. I've done this many times in the past with great success on other systems, but this system is giving me one headache after another and I simply cannot get it to work right. Fix one thing, two more fail...

Another option a Kenwood tech friend of mine mentioned was attaching a controller to the repeater and a mobile on the other side of the controller. Still in discussions on this option...

I'm just looking for simple options that won't break the bank...

Re-program the simplex dispatch radio to transmit on the repeater input, and receive on the repeater output.


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[ramal121]

Trying to wrap my head around what you are attempting here. Clarify for me. Your department has a repeater pair for exclusive use of your radios. You use your repeater when out on a call. You would however, like the simplex dispatch channel which is different from your repeater pair be transmitted out the repeater via a scanning receiver with the same transmit frequency. This I assume is because the repeater will fill out the district which radio coverage is spotty from the simplex dispatch channel. Correct?

Interesting. Well on your first post I didn't have an answer and I thought I'd grab a TKR out of my garage to see exactly what it would do but I've been real busy therefore my silence. I looks like you've checked and the repeater doesn't scan from a repeat channel. Not surprised. But all is not lost. If it will indeed scan when the op mode is set for duplex then I think all you will need is a cheap external controller to bring back the repeat function while in duplex mode (no repeat is possible in simplex mode). This should make the functionality you are looking for.

You will also have to consider scan priority. Will it be used? Which channel? I think your operational channel would have priority so dispatches not for your department would not disrupt important traffic. The drawback to this is if dispatch is is a non-priority scan member the look-back audio hole will kill any audio page sequence (two tone maybe?).

The idea of a separate radio is good too. Keep the TKR on a single repeat channel and wire the second receiver to the accessory.connector. Now priority is set using PTT PRIORITY. No audio holes as would be if you were scanning. Obviously there would be another antenna for second receiver and will probably need some kind of filtering to insure it is not compromised when the repeater is transmitting.

I only did a scanning repeater once many moons ago (not a TKR). Had a few different receive channels as carrier squelch and one transmit channel with different PL's. The idea was to snoop the receive channels for co-channel users and see which one was the least used. The site receive antenna scheme had a window that allowed frequencies over a moderate spread. The transmit combiner was tuned and never changed.

 

[car5le]

So - in our area there is one simplex channel for dispatching several volunteer fire departments. It is a fairly large geographical area and there are some coverage issues, especially for the VFD that I work for. I am not going to go into the specific dynamics and politics of the dispatch center because, quite frankly, they are very different from what I am used to and am still trying to understand the big picture just yet.

Before I joined our VFD, they had licensed a frequency pair and had purchased a TKR-750 with a duplexer. They installed the equipment, but the person who sold them the equipment never came back to program it up. This is where I come in.

I programmed up the TKR and updated programming in all the portable and mobile radios. Then the issue arose that getting dispatch to switch to the new channel to dispatch calls would be a "training issue" and dispatch would be reluctant, if not resistant to another channel in their radio. This is when I thought it would be a good idea to "link" the simplex fire dispatch channel to our new repeater. That way dispatch would not have to "retrain" and it would be business as usual for them.

So, I linked the two systems using two portable radios and a Surcom 629. My initial issues was desensing because the the frequencies on the simplex fire channel and the new repeater are very close. I was able to resolve the desensing issue, but have had constant equipment failures and other typical radio failure. You know - the kind of low budget failure you get when you're trying to put it all together on your income and the VFD doesn't have a budget for the equipment...

Long story short, I'm at my wits end. I did talk with my Kenwood tech friend about hooking a mobile radio to our repeater via a controller. He said he has done it, but he's working, so I'm playing out other options as I wait for him to get back to me.

So, that's it in a nutshell ramal121. Just trying to make things simple for the end user, but having a hell of a time getting it to work...

 

[mmckenna]

Desense is going to be an issue if you are doing this "in band".
Unless you can switch them to UHF, you are going to need to either put a lot of separation between the link radio and the repeater, or if the frequencies are separated enough, add in some notch filtering.

Dispatch centers get cranky any time you get them to try and change how they do things. But still, it might be a good idea to keep trying. Yeah, it's a training thing, especially if they have to switch and dispatch on a separate channel for your department. But it's not an impossible task. Technology is always changing and dispatchers need to be able to change with the times. There will always be some reluctance at first, but eventually they can come around. I suspect they may actually be more concerned about radio and console programming costs. Maybe offering to cover those costs would help.

 

[ramal121]

OK, the more I think about this, an outboard radio hooked directly to the accessory connector of the repeater (without any kind of external controller needed) to receive your dispatches is all you need. Nothing fancy for the receive radio, just something that would provide good line level audio and a receive logic indicator. I'll throw out a Kenwood TK7180 or a NX700 as a good match. Set the PTT priority in the repeater as repeat above external PTT and I believe that would work for you 99% of the time.

The question is how the receive radio will play while the repeater is transmitting also. At a minimum a notch filter may be required on the receive radio.

If you can give us all the frequencies in the mix (roughly if you must) then maybe we can shoot from the hip and suggest how much filtering is required to keep defense down to a minimum.

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[kayn1n32008]

OK, the more I think about this, an outboard radio hooked directly to the accessory connector of the repeater (without any kind of external controller needed) to receive your dispatches is all you need. Nothing fancy for the receive radio, just something that would provide good line level audio and a receive logic indicator. I'll throw out a Kenwood TK7180 or a NX700 as a good match. Set the PTT priority in the repeater as repeat above external PTT and I believe that would work for you 99% of the time.

The question is how the receive radio will play while the repeater is transmitting also. At a minimum a notch filter may be required on the receive radio.

If you can give us all the frequencies in the mix (roughly if you must) then maybe we can shoot from the hip and suggest how much filtering is required to keep defense down to a minimum.

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Depending how high up the repeater antenna is AGL, ERP and depending on how well the dispatch signal is heard at the site, a simple 1/4 or 1/2 wave antenna on a BSA kit on the roof of the shelter would probably not experience too much desense. A single pass can inline would likely be more than adequate.

A TK-7180 or NX-700 is a lot of radio for an application like this. A 8 channel Kenwood or Vertex mobile would be my choice.


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[ramal121]

Depending how high up the repeater antenna is AGL, ERP and depending on how well the dispatch signal is heard at the site, a simple 1/4 or 1/2 wave antenna on a BSA kit on the roof of the shelter would probably not experience too much desense. A single pass can inline would likely be more than adequate.

The main thing is the received signal strength. Since this would be a fixed station to another fixed station the signal should not vary much. If you have say 20 dB of desense (which on a repeater receiver would be a complete buzz kill) your decent receive sensitivity would be about -90dBm. Now if dispatch hits your antenna at -80dBm or better you can get away with maybe no or very minimal filtering. If less then you'll have to jump through a hoop or two.

A TK-7180 or NX-700 is a lot of radio for an application like this. A 8 channel Kenwood or Vertex mobile would be my choice.

This is a suggestion for ease of set-up. Channel capacity does not dictate the ability to interface one radio to another. For example, the TK-7160 DOES NOT provide line level/filtered audio at all. The cheaper NX-720 will do it but you have to crack the radio open and jack with jumpers. A used Motorola is good. A CDM, CM200, or a M1225 will all do what you want with minimal fuss. Can't vouch for Vertex, but stay away from Icom. They are so esoteric/confusing you will be without much hair after you get it all working.


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[RadioCopFFFR]

I know of some fire departments in my area that use a device made by Shinwa that is two tone activated that will record the call information and rebroadcast it on to another frequency that is on another repeater pair. The dispatch channel is VHF and the department's repeater is also on VHF. They have a mobile that is programmed on the county dispatch frequency for receive and the department's repeater input channel on transmit. It makes it where the members of that department don't always have to monitor the county's dispatch channel and hear all the traffic from the neighboring agencies. The only thing is that dispatch had to add a two tone tone to the top of the page stack in the console system so it would activate the rebroadcaster to record the department's page.

 

[mmckenna]

I know of some fire departments in my area that use a device made by Shinwa that is two tone activated that will record the call information and rebroadcast it on to another frequency that is on another repeater pair.

Like a souped up simplex repeater.
Only issue is it would/could create issues with answering back to dispatch. Since it sounds like the link to dispatch isn't used for just dispatching, that could be an issue.

Good approach, though.

A decent radio and proper interfaces, filtering/separation would work.
Considering you can pick up used CDM-750s off e-Bay in the $50-$75 range, it would be an easy solution.

 

[car5le]

Thank you all for your input! This should help me out immensely! I'll let you know how it goes here later this month.