Ok all,
For you turbo masters alike. I see that crescend sells a "Special" digital amplifier for Digital radios like D Star, Trbo, Nex Edge, Etc.
I connected and am using a regular "analog" TPL 100 watt rack mount amp on my trbo box and it seems to work fine. It makes full power upon the repeaters activation and operation.
So, I ask what is with the special "digital" amplifiers. Am I missing something in the RF department that I cant see (dont have Trbo service monitor). Is the amp puking on itself or something of the like?
Thoughts and comments! Thanks, Rob
UHF 100 Watt Amps and Trbo
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Tom in D.C.
- Posts: 3859
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- What radios do you own?: Progreso soup can with CRT
Re: UHF 100 Watt Amps and Trbo
Interesting, to put it mildly. When I run my UHF 6500 HT into an RF Concepts FM amplifier all I get is the
sensing relay chattering in response to the pulsed RF signal from the HT. I assumed that the amplifier just
wouldn't work right with the type signal being sent to it, but I didn't try listening with another TRBO
receiver to the output. I need more information, so anyone else with TRBO/amplifier experience please
jump in.
sensing relay chattering in response to the pulsed RF signal from the HT. I assumed that the amplifier just
wouldn't work right with the type signal being sent to it, but I didn't try listening with another TRBO
receiver to the output. I need more information, so anyone else with TRBO/amplifier experience please
jump in.
Tom in D.C.
In 1920, the U.S. Post Office Department ruled
that children may not be sent by parcel post.
In 1920, the U.S. Post Office Department ruled
that children may not be sent by parcel post.
Re: UHF 100 Watt Amps and Trbo
Tom,
I do see that. If you hook a Trbo radio to a analog watt meter, the needle barley moves, and if it does it is like half power, but that doesn't mean that the radio is not putting out rated power.
The TPL performs very well, no chatter and it seems to be making almost full rated power. However, lately I have noticed a decrease in system performance. Alot of missed calls, half conversations, one guy hearing the transmisson of another when others in the group cant, digital sounds, etc.
I have swept the antenna, duplexer, interconnect cables, etc. Great specs, and no change from original installation. The site is stable, really no changes or new isntallations for other equipment, etc. So I am just poking arond at this point. My thought is maybe the amp finally is giving up??
I do see that. If you hook a Trbo radio to a analog watt meter, the needle barley moves, and if it does it is like half power, but that doesn't mean that the radio is not putting out rated power.
The TPL performs very well, no chatter and it seems to be making almost full rated power. However, lately I have noticed a decrease in system performance. Alot of missed calls, half conversations, one guy hearing the transmisson of another when others in the group cant, digital sounds, etc.
I have swept the antenna, duplexer, interconnect cables, etc. Great specs, and no change from original installation. The site is stable, really no changes or new isntallations for other equipment, etc. So I am just poking arond at this point. My thought is maybe the amp finally is giving up??
Re: UHF 100 Watt Amps and Trbo
I thought Trbo required a linear amp, not a class c rfpa, which use a lot more current. I suspect whatever linear properties the TPL had when it was new have worn out. You can confirm that by bypassing the amp to see if things improve though range and building penetration may reduce somewhat. One of our system engineers mentioned yesterday that the Trbo has an effective 10db native performance increase over conventional. IOW, a 25w system acts like 250w coverage. You may not need the rfpa.
Re: UHF 100 Watt Amps and Trbo
Bill,
I understand what you are saying. The TPL may be a linear amp, most likely is. As far as the effective power of the TRBO system (or I guess most digital formats) "As I understad it" is not about RF propegation, rather where in an analog system you would normally pickett fence on the coverage outskirts of a system, on the digital system you sound 100% in that pickett fence area - so implied is that the didgtal system provides greater RF coverage.
- Rob
I understand what you are saying. The TPL may be a linear amp, most likely is. As far as the effective power of the TRBO system (or I guess most digital formats) "As I understad it" is not about RF propegation, rather where in an analog system you would normally pickett fence on the coverage outskirts of a system, on the digital system you sound 100% in that pickett fence area - so implied is that the didgtal system provides greater RF coverage.
- Rob
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Tom in D.C.
- Posts: 3859
- Joined: Tue Sep 04, 2001 4:00 pm
- What radios do you own?: Progreso soup can with CRT
Re: UHF 100 Watt Amps and Trbo
Bill,
I think you're right about linear vs. class C. Next time I have a chance I'll hook up the 6500 to the amplifier and listen on another 6500 to see what happens when I key it up instead of judging things by what the relay is doing. I'll post a report. Right now I have the deviation meter rather than the scope installed in my Cushman CE6 but I'll change the modules over and see what the signal looks like on the scope; should be interesting.
The TRBO's simplex coverage car-to-car in a city environment is definitely superior to analog FM, we have found. A 3 to 5 db gain UHF antenna, of course, also helps a lot.
Regards,
I think you're right about linear vs. class C. Next time I have a chance I'll hook up the 6500 to the amplifier and listen on another 6500 to see what happens when I key it up instead of judging things by what the relay is doing. I'll post a report. Right now I have the deviation meter rather than the scope installed in my Cushman CE6 but I'll change the modules over and see what the signal looks like on the scope; should be interesting.
The TRBO's simplex coverage car-to-car in a city environment is definitely superior to analog FM, we have found. A 3 to 5 db gain UHF antenna, of course, also helps a lot.
Regards,
Tom in D.C.
In 1920, the U.S. Post Office Department ruled
that children may not be sent by parcel post.
In 1920, the U.S. Post Office Department ruled
that children may not be sent by parcel post.
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Batwings21
- Posts: 930
- Joined: Fri Jun 23, 2006 11:21 am
Re: UHF 100 Watt Amps and Trbo
In my experience, the trbo repeater seems to bring both time-slots on the air any time one is brought up. It does not appear to switch on and off like the mobiles and portables do. If you listen to the output of the portable with an analog monitor you can hear it pulsing and watch a watt meter needle bounce. I did not observe this with the repeaters I just installed.
Re: UHF 100 Watt Amps and Trbo
A normal amplifier should work just fine with Trbo if it works OK with P25 REPEATERS. You are correct, in that the Trbo repeater in digital mode brings up BOTH time slots, so the duty cycle is the same as analog.
Portables only use one time slot or the other, hence the 'chattering' effect. Wattmeters, unless newer digital ones will be too slow to accurately measure the TDMA signal. My HP8920b does just fine with it, and the newer digital service monitors do also.
The NEW MTR3000 is a 100watt Trbo capable repeater, and the newest firmware will allow the repeater to do both analog and digital modes 'mixed' similar to how a Quantar handles P25 or analog on the same channel.
Portables only use one time slot or the other, hence the 'chattering' effect. Wattmeters, unless newer digital ones will be too slow to accurately measure the TDMA signal. My HP8920b does just fine with it, and the newer digital service monitors do also.
The NEW MTR3000 is a 100watt Trbo capable repeater, and the newest firmware will allow the repeater to do both analog and digital modes 'mixed' similar to how a Quantar handles P25 or analog on the same channel.
Re: UHF 100 Watt Amps and Trbo
This is all correct. The amp turned out just fine, it was a bad RX amplifier. Replaced and all is back to normal. - Rob