I picked up a 125 watt VHF quantar (range 1) and have been doing crude tests on the bench. It receives (can hear my audio on the internal speaker) fine but upon powering up and the TX LOCK going active it send outs a continuous transmission which seems to be in carrier. I can use a mic on the quantar itself or us another radio in order to get the quantar to transmit with pl, etc and the signal is much clearer but there is no audio with it. This is on my bench with a 50 ohm dummy load hooked to it and I have checked it from 100 watts down to 40 and I get no audio out (i can still hear audio being received on the internal speaker while the unit is repeatering). Is this normal and I need to set it up on site or is something wrong????
Thanks
Jason
Quantar Repeater - VHF - Questions
Moderator: Queue Moderator
First thing: is it actually making power through the wattmeter when in this condition? If NO power is coming out, continue reading. If significant RF is emanating from the antenna connection, I'd say you have a bigger problem.
Most synthesized transmitters have a fairly strong signal coming from the VCO circuit. This can be heard with a nearby (10 feet) radio tuned to that frequency.
These same radios also usually offer an "Idle Frequency" setting which would default to the single transmitter frequency on a repeater. You should be able to set this to a slightly different frequency, perhaps 50-100 kHz higher or lower than your operating frequency. My UHF MSF5000 has this problem, so I changed the idle freq from 444.450 to 444.400 so I don't hear the unit when I walk into the building.
Choose your idle frequency carefully, so it won't interfere with anything else near it on the site. I believe MTR2000s have the same quirk. It's just something you usually don't worry about and is easily fixed.
Bob M.
Most synthesized transmitters have a fairly strong signal coming from the VCO circuit. This can be heard with a nearby (10 feet) radio tuned to that frequency.
These same radios also usually offer an "Idle Frequency" setting which would default to the single transmitter frequency on a repeater. You should be able to set this to a slightly different frequency, perhaps 50-100 kHz higher or lower than your operating frequency. My UHF MSF5000 has this problem, so I changed the idle freq from 444.450 to 444.400 so I don't hear the unit when I walk into the building.
Choose your idle frequency carefully, so it won't interfere with anything else near it on the site. I believe MTR2000s have the same quirk. It's just something you usually don't worry about and is easily fixed.
Bob M.
Just to add a thought that is implied but not expressed in the prior responses: The Quantar (and the MTR2000) has its exciter continuously powered, whether or not the radio is keyed. In part, the reason for this is to reduce the attack time inherent in waking up and stabilizing an exciter that is allowed to power down between keyed sessions. A receiver on the exciter's frequency will pick up the unmodulated carrier from a distance of a few yards.
The "idle frequency" is the frequency emitted by the exciter during unkeyed time and is adjustable by RSS. For a duplex installation, the Quantar installation manual recommends having the idle frequency equal to the transmit frequency, in order to reduce attack time maximally. However, if the radio is physically located close to where subscribers may be located, this can cause subscriber radios to indicate what appears to be co-channel activity (including interrupting any scan operation), and in such cases the street wisdom is (as others have said) to move the idle frequency a couple of even channels away (paying attention to other occupants of the same site, if your machine is located at a shared site).
For simplex operations, the idle frequency obviously cannot be the transmit frequency, since this would interfere with the Quantar's receiver. The Quantar manual has a set of formulas for recommending a simplex idle frequency.
If I read your post correctly, you also indicate that, when set up as a repeater, the Q is not passing audio. There could be a number of explanations for this, and without actually seeing (and reading) the station, I couldn't hazard a guess as to the problem.
The "idle frequency" is the frequency emitted by the exciter during unkeyed time and is adjustable by RSS. For a duplex installation, the Quantar installation manual recommends having the idle frequency equal to the transmit frequency, in order to reduce attack time maximally. However, if the radio is physically located close to where subscribers may be located, this can cause subscriber radios to indicate what appears to be co-channel activity (including interrupting any scan operation), and in such cases the street wisdom is (as others have said) to move the idle frequency a couple of even channels away (paying attention to other occupants of the same site, if your machine is located at a shared site).
For simplex operations, the idle frequency obviously cannot be the transmit frequency, since this would interfere with the Quantar's receiver. The Quantar manual has a set of formulas for recommending a simplex idle frequency.
If I read your post correctly, you also indicate that, when set up as a repeater, the Q is not passing audio. There could be a number of explanations for this, and without actually seeing (and reading) the station, I couldn't hazard a guess as to the problem.
Well I understand the park frequency now and that totally makes sense.
I did mis type my original post. I am not getting PL out with the unit in normal tx though. I do get full expected RF but im not opening my portable's receive. I have to hit the monitor button on them and then I can hear the STRONG dead air coming across but I have no voice modulation coming across. So its not sending voice or the PL. Does anyone feel this is just a bench problem and would be fine on site? From reading the manual for test procedures its just fine to bench it like this using a 50 ohm dummy load and separate rx antenna.
The unit did come with a mobiltex data cable that goes on plugs 17 and 20 on the back of the unit and then has one of the infamous 15 pin connectors what would go on the back of a spectra. I have tried the quantar with and w/o this cable plugged in with the same result (not hooked up to a spectra though). I cant find anything on this cable however.
Thanks
Jason
I did mis type my original post. I am not getting PL out with the unit in normal tx though. I do get full expected RF but im not opening my portable's receive. I have to hit the monitor button on them and then I can hear the STRONG dead air coming across but I have no voice modulation coming across. So its not sending voice or the PL. Does anyone feel this is just a bench problem and would be fine on site? From reading the manual for test procedures its just fine to bench it like this using a 50 ohm dummy load and separate rx antenna.
The unit did come with a mobiltex data cable that goes on plugs 17 and 20 on the back of the unit and then has one of the infamous 15 pin connectors what would go on the back of a spectra. I have tried the quantar with and w/o this cable plugged in with the same result (not hooked up to a spectra though). I cant find anything on this cable however.
Thanks
Jason
There should NOT be any modulation (audio, PL, DPL) present on the signal when the unit is NOT transmitting. All you should get is a clean carrier from the VCO. Once you key the PTT input, you should have audio etc. If that's how it's working right now, you're good to go and just need to shift the idle frequency.
Bob M.
Bob M.
Ok I have been doing some playing, these are the results:
SCB with firmware 20, no voice modulation and no pl or its off pl
SCB with firmware 16, no voice modulation and no pl or its off pl
SCB with firmware 13, great voice modulation and pl works fine
All have the same codeplug dumped in to them and yes I am working off the original codeplug that came with the quantar. The SCB with 20 firmware was installed the exciter and WL card have matching firmware, in the 20s.
Any ideas? Tuning issue perhaps? Can the PL deviation be set in the tuning?
Jason
SCB with firmware 20, no voice modulation and no pl or its off pl
SCB with firmware 16, no voice modulation and no pl or its off pl
SCB with firmware 13, great voice modulation and pl works fine
All have the same codeplug dumped in to them and yes I am working off the original codeplug that came with the quantar. The SCB with 20 firmware was installed the exciter and WL card have matching firmware, in the 20s.
Any ideas? Tuning issue perhaps? Can the PL deviation be set in the tuning?
Jason
Jason,
Although I'm more into MSF's I tend to think there are a lot of similarities between the two.
How exactly is the station being keyed? Local tx switch, local mic or an exterior rf source. On an MSF station it does make a difference in your audio and pl paths depending on how the station is keyed.
Doug
Although I'm more into MSF's I tend to think there are a lot of similarities between the two.
How exactly is the station being keyed? Local tx switch, local mic or an exterior rf source. On an MSF station it does make a difference in your audio and pl paths depending on how the station is keyed.
Doug
May the Schwarz be with you.
Again noting that long distance diagnoses are, at best, speculation, a dollar to a dime says it is a programming issue.
The codeplug values are contained in the Station Control Module (SCM). At the risk of going way out on a limb, the SCMs that aren't working may have been programmed for a voted system, with the station type set as "Base" and keying dependent upon wireline signals from a SpectraTac Tone Keying Module, while the SCM that is working is programmed for station type as "Repeater," which is the setting for what we would call an "in cabinet" repeater and is capable of being keyed by the qualifiation of the receiver and, when so keyed, will pass receiver audio and programmed output PL.
The codeplug values are contained in the Station Control Module (SCM). At the risk of going way out on a limb, the SCMs that aren't working may have been programmed for a voted system, with the station type set as "Base" and keying dependent upon wireline signals from a SpectraTac Tone Keying Module, while the SCM that is working is programmed for station type as "Repeater," which is the setting for what we would call an "in cabinet" repeater and is capable of being keyed by the qualifiation of the receiver and, when so keyed, will pass receiver audio and programmed output PL.
I suspect something more sinister as well. The original board doesn't work which is CLN6961. This is the one the unit came with.
The second board is TTN4094 which has the same result of the CLN5961 board (dead air tx when programmed for analog and PL operation , ie no voice modulation no pl ).
The 3rd is TRN7475 which works fine. Of course this one doesn't support IMBE which is the whole point of having a quantar,
.
Also on the CLN and TTN boards I noticed that there is a very small set of dipswitch on the board, anyone know what these do?
Jason
The second board is TTN4094 which has the same result of the CLN5961 board (dead air tx when programmed for analog and PL operation , ie no voice modulation no pl ).
The 3rd is TRN7475 which works fine. Of course this one doesn't support IMBE which is the whole point of having a quantar,
.Also on the CLN and TTN boards I noticed that there is a very small set of dipswitch on the board, anyone know what these do?
Jason
Last edited by jmr061 on Sun Dec 24, 2006 8:46 am, edited 1 time in total.
ok so everything is fairly up to date.
If you hold the controller with the sims at the top
have look about middle and 3/4 to the right.
There is a 12 or 14 pin chip.
We once had a lightning strike that blew this chip on 6 repeaters.
The fault was similar (although in a trunking configeration)
no repeat audio.
The chip in the cct diagram passes repeat audio through the system.
I'm out of office till next year so I cant look up the chip number but ours all had the top fried to some extent. have a good look with a magnifier at the smaller chips away from the actual logic area. If you have the manual it shouldnt be to hard to find it on the diagram
If you hold the controller with the sims at the top
have look about middle and 3/4 to the right.
There is a 12 or 14 pin chip.
We once had a lightning strike that blew this chip on 6 repeaters.
The fault was similar (although in a trunking configeration)
no repeat audio.
The chip in the cct diagram passes repeat audio through the system.
I'm out of office till next year so I cant look up the chip number but ours all had the top fried to some extent. have a good look with a magnifier at the smaller chips away from the actual logic area. If you have the manual it shouldnt be to hard to find it on the diagram
Start by taking the RSS into the service screen, then hardware configuration, then validate configuration [F2 - F2 - F8] to be sure the RSS thinks the codeplug is compatible with the station.
Then look at the station's wildcard programming. If there was other stuff hung on the Quantar, it is probable that the functions of that equipment were defined through wildcard programming. Something in that programming may be your issue.
One reason the TRN7475 SCB works might be that the old firmware does not recognize wildcard and therefore ignores whatever is in the codeplug that is creating your issue with the other boards.
Then look at the station's wildcard programming. If there was other stuff hung on the Quantar, it is probable that the functions of that equipment were defined through wildcard programming. Something in that programming may be your issue.
One reason the TRN7475 SCB works might be that the old firmware does not recognize wildcard and therefore ignores whatever is in the codeplug that is creating your issue with the other boards.
There is no wildcard installed. There was something else hooked up to it via P17 and P20 as there is a cable for that. I can't get into the wildcard settings as there isn't one installed.
I am also using windows ver 14 rss.
Here are some pics of the SCM. What chip are you talking about?
Here are the pics of the scm, what chip is it?
Jason
I am also using windows ver 14 rss.
Here are some pics of the SCM. What chip are you talking about?
Here are the pics of the scm, what chip is it?
Jason