My VFD recieved Uncle Sam money to replace/upgrade our VHF repeaters. I need help in understanding what we really need in equipment and how much $ we may be looking at.
Fx pair A: 150.775 / 155.385 output 110w. ERP 150w
Fx pair B: 150.805 / 154.220 output 100w ERP 98w
What output power do I need for the repeaters and what type antennas? T/R antennas or duplexer? Coax type? Can they both be at same location or will I have interference? Sorry for all the questions, but I am being told everthing from local shops. I have more faith in you guys to head me in the right direction.
We have 2 locations proposed to relocate to.
First is a water tower. Cable length would be 50 feet +/-
Second is a 100 ft steel pole tower on a hill top.
Will a 50w repeater (Kenwood TKR750, etc) work? Help!
Repeaters - What do we really need?
Moderator: Queue Moderator
A single site is the cheapest since it only requires one antenna, one feed line and one duplexer. Go for the highest site central to your coverage area.
The repeater transmitters can be coupled together with a hybrid combiner (Sinclair TC-2112) and fed to the TX side of the duplexer. This is needed since your TX frequencies are very close together. The Hybrid combiner panel has circulators onboard to provide additional isolation and suppress intermods.
The receivers are coupled into a receive multicoupler (Sinclair RM21202/N) and connected to the RX side of the duplexer. The receive multicoupler includes a 4.7 dB gain amp that makes up for the receive multicoupler and duplexer losses.
The duplexer can be a Sinclair Q-2220E. It provides the required 70 dB rejection for your TX-RX frequency spacing.
The antenna selection depends on the type of terrain and the coverage needed but likely will be a 6 dB gain omni antenna. The TX power is adjusted to the maximum allowed ERP that is produced by the antenna taking into account the equipment losses.
The TX hybrid combiner has a 3.7 dB loss. The duplexer has about 1 dB loss. The feedline (Andrew LDF4-50 Heliax) has about 1 dB loss. So the total losses are going to be at least 6 dB. When using a 6 dB gain omni antenna, these losses are cancelled.
This means that you will need a 100-watt repeater in order to get 100 watt ERP. I suggest a Motorola MTR2000.
Nand.
The repeater transmitters can be coupled together with a hybrid combiner (Sinclair TC-2112) and fed to the TX side of the duplexer. This is needed since your TX frequencies are very close together. The Hybrid combiner panel has circulators onboard to provide additional isolation and suppress intermods.
The receivers are coupled into a receive multicoupler (Sinclair RM21202/N) and connected to the RX side of the duplexer. The receive multicoupler includes a 4.7 dB gain amp that makes up for the receive multicoupler and duplexer losses.
The duplexer can be a Sinclair Q-2220E. It provides the required 70 dB rejection for your TX-RX frequency spacing.
The antenna selection depends on the type of terrain and the coverage needed but likely will be a 6 dB gain omni antenna. The TX power is adjusted to the maximum allowed ERP that is produced by the antenna taking into account the equipment losses.
The TX hybrid combiner has a 3.7 dB loss. The duplexer has about 1 dB loss. The feedline (Andrew LDF4-50 Heliax) has about 1 dB loss. So the total losses are going to be at least 6 dB. When using a 6 dB gain omni antenna, these losses are cancelled.
This means that you will need a 100-watt repeater in order to get 100 watt ERP. I suggest a Motorola MTR2000.
Nand.
Will there be any problems with both repeaters being activated at the same time? Any idea what I should pay for the MTR2000? Have an estimate of what all this equipment would cost? I am sorry for the questions, but I want to make sure I am not being shafted.
The area vendors have all said we need seperate antennas for each repeater $$.
I appreciate your assistance.
The area vendors have all said we need seperate antennas for each repeater $$.
I appreciate your assistance.
John B
Yes, this will allow both repeaters to be used at the same time without causing any interference from one to the other one.
Using two antennas often produces problems that are difficult to circumvent since the coupling between the two systems in not fixed. A single antenna in a multi-repeater system produces 100% predictable results as far as desense. It also reduces the cost because of sharing of some components.
Provide your TX and RX frequencies, power levels etc. for both repeaters to one of the antenna companies like Sinclair or TX-RX Systems and ask for to a quote. They will indicate the needed equipment (not much different from my previous reply) and a price. Also have them include a rack and possible the interconnecting cables.
For pricing including installation, you likely should ask some competent local dealers.
Nand.
Using two antennas often produces problems that are difficult to circumvent since the coupling between the two systems in not fixed. A single antenna in a multi-repeater system produces 100% predictable results as far as desense. It also reduces the cost because of sharing of some components.
Provide your TX and RX frequencies, power levels etc. for both repeaters to one of the antenna companies like Sinclair or TX-RX Systems and ask for to a quote. They will indicate the needed equipment (not much different from my previous reply) and a price. Also have them include a rack and possible the interconnecting cables.
For pricing including installation, you likely should ask some competent local dealers.
Nand.
-
Birken Vogt
- Posts: 262
- Joined: Thu Nov 10, 2005 7:53 pm
Well specifically regarding the TKR750, it is a nice unit, but being run at full power they have a reputation for blowing the finals. So I would try to run it at less than 50 watts. We are installing a system using 3 of them right now and IIRC they are putting out in the 25-35 range somewhere.
If Uncle Sam is being generous with his money a TKR-740 has more features and specifications but it is just an exciter, it does not put out any RF power of its own so it needs an afterburner.
If rack space is a consideration, from the looks of the case on the 750, two repeaters could be placed in the body side by side, you'd have to call Kenwood to make sure though but it sure looks like it is possible. They are 3-1/2" tall I think.
As far as the filters go, yes, you just need to call the manufacturers and tell them what you want and they will tell you how to get there and ship it pre-tuned. We like Telewave but there is another one out there with a 3-letter name which I forget now that is cheaper and is supposed to be good.
Typically we run 4-6 transmitters with similar freqs into a combiner onto one antenna at 60-80' and the same 4-6 recievers from an antenna up 100-120' instead of using one antenna for all. These are on very high hills.
But in your case I think since you will likely not be sharing your antenna(s) with anyone else a single one up as high as you can get would be best for transmit and recieve. Work out the cost difference between the filters for a single antenna vs two antennas, etc.
If you can supply me with exact GPS coordinates of the proposed sites and the tower heights I can work up a coverage map with Radio Mobile software...accuracy not guaranteed but it gives a good idea
Birken
If Uncle Sam is being generous with his money a TKR-740 has more features and specifications but it is just an exciter, it does not put out any RF power of its own so it needs an afterburner.
If rack space is a consideration, from the looks of the case on the 750, two repeaters could be placed in the body side by side, you'd have to call Kenwood to make sure though but it sure looks like it is possible. They are 3-1/2" tall I think.
As far as the filters go, yes, you just need to call the manufacturers and tell them what you want and they will tell you how to get there and ship it pre-tuned. We like Telewave but there is another one out there with a 3-letter name which I forget now that is cheaper and is supposed to be good.
Typically we run 4-6 transmitters with similar freqs into a combiner onto one antenna at 60-80' and the same 4-6 recievers from an antenna up 100-120' instead of using one antenna for all. These are on very high hills.
But in your case I think since you will likely not be sharing your antenna(s) with anyone else a single one up as high as you can get would be best for transmit and recieve. Work out the cost difference between the filters for a single antenna vs two antennas, etc.
If you can supply me with exact GPS coordinates of the proposed sites and the tower heights I can work up a coverage map with Radio Mobile software...accuracy not guaranteed but it gives a good idea
Birken
Personally, as far as combining everything onto one antenna, I'd call RFSCelwave and tell them what you're trying to build and have them tune and ship a combiner system for you that's ready to go. No offense, but if you're asking for directions on doing this, you probably don't have the test equipment and time to put components together and tune them properly. Plus, having a vendor-certified solution is always good in PS applications.
If you're running anything over 50', I'd run LDF5 (7/8" hardline).
I'm a big fan of the TKR-750s. Mine are running at 5 watts driving an external 150watt power amp. These were burned in running 24 hours continuous key into a dummy load, then 5 minutes on/5 minutes off for 24 hours. No problems with anything failing. Also, the Version 2 repeaters have all sorts of cool options in the internal controller... IDer, DTMF remote control, battery backup, ad nauseum.
Just a few more thoughts...
If you're running anything over 50', I'd run LDF5 (7/8" hardline).
I'm a big fan of the TKR-750s. Mine are running at 5 watts driving an external 150watt power amp. These were burned in running 24 hours continuous key into a dummy load, then 5 minutes on/5 minutes off for 24 hours. No problems with anything failing. Also, the Version 2 repeaters have all sorts of cool options in the internal controller... IDer, DTMF remote control, battery backup, ad nauseum.
Just a few more thoughts...
Quoted from above "But in your case I think since you will likely not be sharing your antenna(s) with anyone else a single one up as high as you can get would be best for transmit and recieve. Work out the cost difference between the filters for a single antenna vs two antennas, etc. ""
Your FCC license info will list the required licensed height depending on your coverage area. You cannot just go and put your antenna at any height that you desire, remember you have to meet this height limit and should not go over or under what is on the FCC docs otherwise you could be in violation of the build permit.
Mike
Your FCC license info will list the required licensed height depending on your coverage area. You cannot just go and put your antenna at any height that you desire, remember you have to meet this height limit and should not go over or under what is on the FCC docs otherwise you could be in violation of the build permit.
Mike
With how the grant was written it is not a requirement. We requested VHF conventional with narrowband capabilities. We can't afford to go digital at this point, not to mention try to go trunking. We don't have the call volume to justify recieving funding for that. Plus we would not be able to talk to area FD's (don't really care about talking to SO).
John B
I really appreciate all the feedback. I got tagged with this project since I wrote the grant proposal and had radio experience (funny how nobody wants to help, but sure like to gripe).
Whenever I do a project I like to learn as much about it as possible. I am not a tech, don't pretend to be. I have experience in conventional mobile and base installations but have never delt with repeaters. I feel confident about doing the actual install if necessary ( I am very particular about my installs). Everything depends on $$ of project.
Fact is, our current setup won't meet the basic coverage needs and that concerns me.
That is why I have asked all of these questions and I really appreciate the feedback.
Here are a few more: Some of the post referring to the TKR750 talk about reducing the output and adding an external PA. Is this a reliable setup for a VFD and where can I find the external PA. I can purchase several TKR750 for the price of the MTR2000.
What I am needing to know is can I put 2 repeaters in operation for around $15-18K. One at 150w ERP and the other at 98w ERP using the single antenna and combiner concept that would be reliable?
Whenever I do a project I like to learn as much about it as possible. I am not a tech, don't pretend to be. I have experience in conventional mobile and base installations but have never delt with repeaters. I feel confident about doing the actual install if necessary ( I am very particular about my installs). Everything depends on $$ of project.
Fact is, our current setup won't meet the basic coverage needs and that concerns me.
That is why I have asked all of these questions and I really appreciate the feedback.
Here are a few more: Some of the post referring to the TKR750 talk about reducing the output and adding an external PA. Is this a reliable setup for a VFD and where can I find the external PA. I can purchase several TKR750 for the price of the MTR2000.
What I am needing to know is can I put 2 repeaters in operation for around $15-18K. One at 150w ERP and the other at 98w ERP using the single antenna and combiner concept that would be reliable?
John B
I've only limited experience with the TKR750/850 series, but they are solidly built & are rated for continuous duty at 25 watts, not their maximum of 50...which could explain the blown finals if they exceeded a 50% duty cycle at maximum power.
For the money, they are hard to beat. I suggest you order them factory programmed & tuned to your frequencies, as they are NOT "program & play" like the MTR2000...they can require quite a bit of alignment from their factory default settings depending on how far away your frequency is from the default. As a tech who's aligned a lot of things, I still found the TKR to be tricky.
Don't forget about a power supply for them, as it's an option, not standard equipment. Tvsjr can elaborate on American pricing & what external amp to use. As you noted, you could easily purchase a back-up TKR & still come out ahead of the MTR2000.
If going Motorola, I'd certainly go with the MTR2000 if money allows. Can't beat them as an analog repeater...just pricey.
Todd
For the money, they are hard to beat. I suggest you order them factory programmed & tuned to your frequencies, as they are NOT "program & play" like the MTR2000...they can require quite a bit of alignment from their factory default settings depending on how far away your frequency is from the default. As a tech who's aligned a lot of things, I still found the TKR to be tricky.
Don't forget about a power supply for them, as it's an option, not standard equipment. Tvsjr can elaborate on American pricing & what external amp to use. As you noted, you could easily purchase a back-up TKR & still come out ahead of the MTR2000.
If going Motorola, I'd certainly go with the MTR2000 if money allows. Can't beat them as an analog repeater...just pricey.
Todd
No trees were harmed in the posting of this message...however an extraordinarily large number of electrons were horribly inconvenienced.
Welcome to the /\/\achine.
Welcome to the /\/\achine.
Yep, Todd's right, they aren't "program and play". The good part about that is it means they have a *tight* front end and survive very well in RF sewers (jban, you probably know about the Green Building in DFW and the RF sewer of downtown... won't even phase an x50).
Todd, I am surprised that you had a tough time getting one properly aligned. Do you have the service manual cheat sheet? There's a very nice, step-by-step procedure complete with equipment required, test points to connect to, and desired values. Normally, the ones I've found coming out of the box are in good shape as far as the deviations/etc. Usually, all I have to do is tune the bandpass filter and confirm everything else... in a pinch, I've been known to tune the bandpass filter by ear (yeah, I know, bad geek!)
I'm afraid there's no way in hell to make this happen if you're buying two MTRs for the budget you have. It's going to be really tight to get'er'done using Kenwood stuff, considering the lion's share of the hardware expense is going to hit in the RF conditioning hardware.
jban, which department is this for, if you don't mind me asking? I'm just up the road here in D/FW.
As far as the power supply, I recommend going with an external unit. It takes up more space, but having the meters is nice, and you have less of a heat issue. Buy a spare, they're cheap.
As for pricing:
TKR-750K VHF 146-174MHz, 25-50W, Base-Repeater - $1,483.00
KPG-46 Programming interface cable - $109.00
KPG-91D Programming Software - $39.00
L-916 Tune TKR-750/850 - $30.00
L-923 RX center freq adjustment for TKR-750/850 - $25.00
Note: Kenwood specifically calls out the Telewave TPRD-1556 6-cavity BpBr duplexer for this unit.
So, you're looking at $3,224 for two repeaters and one set of programming hardware. This is list pricing... you can probably get a dealer to knock of 25% off that.
For external amps, I'm currently using an old Midland LMR 150-watt base station amp. I'm not usually a Midland fan, but this thing is built like a brick shithouse, and the price was right (free).
For the site infrastructure (combiner/duplexer/etc.), I'd look at RFSCelwave, Telewave, and maybe EMR. Call each of them, tell them what you're trying to do, and have them build you a quote for a complete system as far as RF conditioning. If you don't have the test equipment, time, and patience, you're going to be a lot better off getting this stuff direct from them, so that it's tuned and ready to go.
For the power amps, I'd look at EMR (they've got a 22-watt-in/100-watt-out brick that's a good match), TPL, or Crescend.
Both of your sites are likely to be lightning magnets. You need to get a firm grasp on grounding (does the site have a halo ground system... is everything bonded... crappy clamps or good exothermic welds... what's the resistance to ground... etc.) to make all this work properly and not fail when the storms roll through.
Spec in spare hardware... repeater, power supply, power amp, lightning protectors, jumper coax, connectors, etc. The RF conditioning stuff isn't going to blow up unless something really serious happens... everything else is much more vulnerable.
Think about backup power... the TKR has a nice interface for backup power, but the amps generally don't. A device like a Heart Interface would be really useful to handle the power management. I don't have much experience with them, but there are plenty of people here that do. More $$$.
If you do this right, you're going to be squeezing on that budget. Start putting quotes together and prepare to try to pull another few K out of somewhere (department budget, county, whatever).
Todd, I am surprised that you had a tough time getting one properly aligned. Do you have the service manual cheat sheet? There's a very nice, step-by-step procedure complete with equipment required, test points to connect to, and desired values. Normally, the ones I've found coming out of the box are in good shape as far as the deviations/etc. Usually, all I have to do is tune the bandpass filter and confirm everything else... in a pinch, I've been known to tune the bandpass filter by ear (yeah, I know, bad geek!)
I'm afraid there's no way in hell to make this happen if you're buying two MTRs for the budget you have. It's going to be really tight to get'er'done using Kenwood stuff, considering the lion's share of the hardware expense is going to hit in the RF conditioning hardware.
jban, which department is this for, if you don't mind me asking? I'm just up the road here in D/FW.
As far as the power supply, I recommend going with an external unit. It takes up more space, but having the meters is nice, and you have less of a heat issue. Buy a spare, they're cheap.
As for pricing:
TKR-750K VHF 146-174MHz, 25-50W, Base-Repeater - $1,483.00
KPG-46 Programming interface cable - $109.00
KPG-91D Programming Software - $39.00
L-916 Tune TKR-750/850 - $30.00
L-923 RX center freq adjustment for TKR-750/850 - $25.00
Note: Kenwood specifically calls out the Telewave TPRD-1556 6-cavity BpBr duplexer for this unit.
So, you're looking at $3,224 for two repeaters and one set of programming hardware. This is list pricing... you can probably get a dealer to knock of 25% off that.
For external amps, I'm currently using an old Midland LMR 150-watt base station amp. I'm not usually a Midland fan, but this thing is built like a brick shithouse, and the price was right (free).
For the site infrastructure (combiner/duplexer/etc.), I'd look at RFSCelwave, Telewave, and maybe EMR. Call each of them, tell them what you're trying to do, and have them build you a quote for a complete system as far as RF conditioning. If you don't have the test equipment, time, and patience, you're going to be a lot better off getting this stuff direct from them, so that it's tuned and ready to go.
For the power amps, I'd look at EMR (they've got a 22-watt-in/100-watt-out brick that's a good match), TPL, or Crescend.
Both of your sites are likely to be lightning magnets. You need to get a firm grasp on grounding (does the site have a halo ground system... is everything bonded... crappy clamps or good exothermic welds... what's the resistance to ground... etc.) to make all this work properly and not fail when the storms roll through.
Spec in spare hardware... repeater, power supply, power amp, lightning protectors, jumper coax, connectors, etc. The RF conditioning stuff isn't going to blow up unless something really serious happens... everything else is much more vulnerable.
Think about backup power... the TKR has a nice interface for backup power, but the amps generally don't. A device like a Heart Interface would be really useful to handle the power management. I don't have much experience with them, but there are plenty of people here that do. More $$$.
If you do this right, you're going to be squeezing on that budget. Start putting quotes together and prepare to try to pull another few K out of somewhere (department budget, county, whatever).
-
Birken Vogt
- Posts: 262
- Joined: Thu Nov 10, 2005 7:53 pm
That is interesting, we just installed 3 TKR750s and none of them required any tweaking. Maybe they have changed or possibly they were in the right range already, I don't know.wavetar wrote:I've only limited experience with the TKR750/850 series, but they are solidly built & are rated for continuous duty at 25 watts, not their maximum of 50...which could explain the blown finals if they exceeded a 50% duty cycle at maximum power.
For the money, they are hard to beat. I suggest you order them factory programmed & tuned to your frequencies, as they are NOT "program & play" like the MTR2000...they can require quite a bit of alignment from their factory default settings depending on how far away your frequency is from the default. As a tech who's aligned a lot of things, I still found the TKR to be tricky.
Birken
It would depend on how far away from the factory default frequency you need to be. In my case, they were low-split UHF units which were tuned to 415MHz at the factory, and I had to move them over 13MHz to 428.xxxx for our system. If you're only a couple of MHz away, they might not need much at all. But as tvsjr confirms, they aren't normally program & play.Birken Vogt wrote: That is interesting, we just installed 3 TKR750s and none of them required any tweaking. Maybe they have changed or possibly they were in the right range already, I don't know.
Birken
Todd
No trees were harmed in the posting of this message...however an extraordinarily large number of electrons were horribly inconvenienced.
Welcome to the /\/\achine.
Welcome to the /\/\achine.
Unless you ordered the option codes to have the repeaters tuned (requires giving Kenwood the operating channel), then the repeater MUST have a full alignment performed before being deployed. At the very least, the front-end bandpass filter must be properly aligned using a spec-an/TG or the receiver will not perform to spec.Birken Vogt wrote:That is interesting, we just installed 3 TKR750s and none of them required any tweaking. Maybe they have changed or possibly they were in the right range already, I don't know.
Birken