|
Greetings Gang,
I have a question for those QUANTAR Gurus in the group.
I need to feed wide band analog audio - from 50 Hz to 6 kHz into the transmitter modulator.? I've found a place just ahead of the 6 kHz splatter filter, but was hoping to find a place that didn't require me to dig into and modify the back plane board.
My question: Is there a place on any of the connectors on the back of the radio where I can inject wide band analog audio?
The normal restricted analog in and out on the orange connector will not work for my needs.? I need the wideband analog input.
Thanks,
Burt, K6OQK
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IIRC the 50pin Telco? connector has a flat RX and TX connections that should meet your needs . Just about everything is available on that connector.
I've had problems interfacing a Quantar to an external controller.. I did all the necessary wild card function settings, and it didn't work right. I'm in no big hurry to figure it out. But eventually I have another Quantar that I want to put a RLC controller on. The first Quantar got replaced by a TKR 750V2 and a TPL amp which is working like gangbusters.
Chris WB5ITT?
On Sun, Oct 23, 2022, 5:50 PM Burt K6OQK < biwa@...> wrote: Greetings Gang,
I have a question for those QUANTAR Gurus in the group.
I need to feed wide band analog audio - from 50 Hz to 6 kHz into the transmitter modulator.? I've found a place just ahead of the 6 kHz splatter filter, but was hoping to find a place that didn't require me to dig into and modify the back plane board.
My question: Is there a place on any of the connectors on the back of the radio where I can inject wide band analog audio?
The normal restricted analog in and out on the orange connector will not work for my needs.? I need the wideband analog input.
Thanks,
Burt, K6OQK
|
As a Kenwood Dealer, I kinda felt like Benedict Arnold installing a
Quantar for my 2 mtr repeater but I did and it works great with (of
course) an RC210. (using the Telco connector and it has the wireline card
of course)
An added bonus is that I have AREDN Mesh at this site and am running a
Promox computer with a Win7 VM. I run the Motorora RSS software and it is
nice being able to monitor RX/TX performance in real time
Ken
At 05:12 PM 10/23/2022, you wrote:
toggle quoted message
Show quoted text
IIRC the 50pin Telco??
connector has a flat RX and TX connections that should meet your needs .
Just about everything is available on that connector.
I've had problems interfacing a Quantar to an external controller.. I did
all the necessary wild card function settings, and it didn't work right.
I'm in no big hurry to figure it out. But eventually I have another
Quantar that I want to put a RLC controller on. The first Quantar got
replaced by a TKR 750V2 and a TPL amp which is working like
gangbusters.
Chris WB5ITT?
On Sun, Oct 23, 2022, 5:50 PM Burt K6OQK
<biwa@...> wrote:
- Greetings Gang,
- I have a question for those QUANTAR Gurus in the group.
- I need to feed wide band analog audio - from 50 Hz to 6 kHz into the
transmitter modulator.?? I've found a place just ahead of the 6 kHz
splatter filter, but was hoping to find a place that didn't require me to
dig into and modify the back plane board.
- My question: Is there a place on any of the connectors on the back of
the radio where I can inject wide band analog audio?
- The normal restricted analog in and out on the orange connector will
not work for my needs.?? I need the wideband analog input.
- Thanks,
- Burt, K6OQK
------------------------------------------------------------------------------
President and CTO - Arcom Controllers
Makers of repeater controllers and accessories
Phone: (503) 678 6182
Authorized Dealers for Kenwood and Telewave.
We offer complete turn-key repeater packages!
"We don't just make 'em. We use 'em!"
![[]](http://www.arcomcontrollers.com/arcom.png)
|
The general transmit audio input (+ and -) on the 50 pin telco
connector.
You may need to set the station to simulcast to get this input
active?
Thanks, 73, Jim W7RY
On 10/23/2022 5:50 PM, Burt K6OQK
wrote:
toggle quoted message
Show quoted text
Greetings Gang,
I have a question for those QUANTAR Gurus in the group.
I need to feed wide band analog audio - from 50 Hz to 6 kHz into
the transmitter modulator.? I've found a place just ahead of the 6
kHz splatter filter, but was hoping to find a place that didn't
require me to dig into and modify the back plane board.
My question: Is there a place on any of the connectors on the back
of the radio where I can inject wide band analog audio?
The normal restricted analog in and out on the orange connector
will not work for my needs.? I need the wideband analog input.
Thanks,
Burt, K6OQK
|
All,
Thank you for your replies.? However, I need wideband analog input, not the typical/normal 250-3000 Hz audio.? The wideband audio is from darn near DC to 5+ kHz.
I was hoping the "Aux TX Audio"? on pin 5 of the 50 pin connector would be it, but it appears to only be 250-3000 Hz, or less.
Unfortunately I only have the service manual in pdf form.? Trying to find what I'm looking for in that is giving me a krik in my neck and my peepers are becoming crossed.?
If you look at the exciter schematic you will see pin-78 of P/O P-102 .? It's called, "VCO AUDIO" and goes into the 6 kHz splatter filter circuitry and then directly to the "Varactor modulator," CR3250.? I may have to break down and access this by modifying the back plane board.? Being lazy, I was hoping for something simple.
Burt, K6OQK
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Fwiw. I have used Mark dannons cables for numerous projects and have several in service since 2013 no issues.? ?
N3ssl?
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I'll try to check a copy of the manual here at the HQ in Austin tomorrow....my manual is back at my office in Beaumont.
Chris WB5ITT CET III Texas Department of Public Safety?
On Mon, Oct 24, 2022, 8:25 PM Burt K6OQK < biwa@...> wrote: All,
Thank you for your replies.? However, I need wideband analog input, not the typical/normal 250-3000 Hz audio.? The wideband audio is from darn near DC to 5+ kHz.
I was hoping the "Aux TX Audio"? on pin 5 of the 50 pin connector would be it, but it appears to only be 250-3000 Hz, or less.
Unfortunately I only have the service manual in pdf form.? Trying to find what I'm looking for in that is giving me a krik in my neck and my peepers are becoming crossed.?
If you look at the exciter schematic you will see pin-78 of P/O P-102 .? It's called, "VCO AUDIO" and goes into the 6 kHz splatter filter circuitry and then directly to the "Varactor modulator," CR3250.? I may have to break down and access this by modifying the back plane board.? Being lazy, I was hoping for something simple.
Burt, K6OQK
|
Then you did not see my reply.
The general transmit input is uses for simulcast. It passes DC to
10 KHz with no issues.
Connector 17, (50 pin telco)Pins 9 and 34
Thanks, 73, Jim W7RY
On 10/24/2022 8:25 PM, Burt K6OQK
wrote:
toggle quoted message
Show quoted text
All,
Thank you for your replies.? However, I need wideband analog
input, not the typical/normal 250-3000 Hz audio.? The wideband
audio is from darn near DC to 5+ kHz.
I was hoping the "Aux TX Audio"? on pin 5 of the 50 pin connector
would be it, but it appears to only be 250-3000 Hz, or less.
Unfortunately I only have the service manual in pdf form.? Trying
to find what I'm looking for in that is giving me a krik in my
neck and my peepers are becoming crossed.?
If you look at the exciter schematic you will see pin-78 of P/O
P-102 .? It's called, "VCO AUDIO" and goes into the 6 kHz splatter
filter circuitry and then directly to the "Varactor modulator,"
CR3250.? I may have to break down and access this by modifying the
back plane board.? Being lazy, I was hoping for something simple.
Burt, K6OQK
|
Burt,
Interestingly enough, I was hoping to
look at a Quantar this winter to get to that line and see how flat
it is. It has DC, so a cap is called for, and I don't know what
the source impedance of that line is, so a good op-amp with the
proper build out resistor might be needed.
And then, that receiver. The Quantar
uses that special IC, but I looked at the schematic briefly, and
it looks like the IC delivers I/Q audio. Well, a simple I/Q
decoder should give us flat audio, me thinks. I would like to end
up with a repeater that is flat from 50 hz to 5000 hz. A notch
filter on the rx Pl tone, and an external audio limiter. Yes, we
only need 300-2500 for communications. But, this is ham radio !
Tom (now retired) K8TB
On 10/24/2022 9:25 PM, Burt K6OQK
wrote:
toggle quoted message
Show quoted text
If you look at the exciter schematic you will see pin-78 of P/O
P-102 .? It's called, "VCO AUDIO" and goes into the 6 kHz splatter
filter circuitry and then directly to the "Varactor modulator,"
CR3250.? I may have to break down and access this by modifying the
back plane board.? Being lazy, I was hoping for something simple.
Burt, K6OQK
|
Jim,
Thank you. You saved me a whole lot of
work!
Tom K8TB
On 10/24/2022 9:35 PM, Jim W7RY via
groups.io wrote:
toggle quoted message
Show quoted text
Then you did not see my reply.
The general transmit input is uses for simulcast. It passes DC
to 10 KHz with no issues.
Connector 17, (50 pin telco)Pins 9 and 34
|
When I first saw the question, I scratched my head and went on to other things.? It looked wierd.? Then I remembered why.?
If you are actually going to feed audio up to 6 khz. to the modulator, where does it actually go after that???
Even if you reduce the deviation and the pre-emphasis to keep the bandwidth down to a normal FM channel, anyone trying
to recieve it will have to modify the reciever so it won't squelch itself out trying to recieve.?
?
Sounds confusing, but the typical 16kF3 reciever needs to have a 20khz bandwidth in the IF to allow for drift and to prevent
the reciever from squelching out.? The back-end was made to roll off above 3khz to the speech amp and the squelch amp will
be listening for noise above that to keep the squelch closed.?
If this is for a link radio on the 2m ham band, how were you planning to keep the bandwidth to a normal ham channel?? If this is
for a ham voice repeater, everyone will have to modify their radios to use it.? If for commercial, you would have to re-engineer the
Quantar and apply for a new FCC certification.
Or are you planning on jamming out some people?? If you remove the splatter filter, you could concievably take up the whole
2m band depending on the actual bandwidth of the PA.? Or you could do away with the Quantar entirely and move up to a FM
stereo broadcast station with extra muxed channels.
|
Ok guys...
You bring up a lot of interesting points, but nothing new to me.? Let me say that I've been in the 2-Meter repeater business for over 60 years.? I've always prided myself in good performance and good audio quality.? To me, and to many others, 300-3000 Hz audio doesn't cut it.? As it was said, this is Amateur Radio.? :)
The reason I want to access the wide band audio is to stay away from the typical narrow sound of many repeaters.? If you're in the southern California area, take a listen to the W6MEP 2-Meter repeater on 147.24 MHz.? It's very compatible with all 5 kHz dev radios, commercial and others.? The audio out of the completely home brewed receiver is wide band - 50 Hz to a little over 6 kHz? There is a very narrow P.L. notch filter in the controller.? The transmitter is direct FM. The modulation index is barely 1.? I do have audio processing in the system in the way of an Orban FM 8100A Optimod. (I do have the stereo turned off.) I have a low pass filter between the output of the processing and the input to the modulator.? The deviation is 4-4.5 kHz and is very consistent without sucking up noise between words.? The repeater is very transparent except that the transmitted audio is pretty consistent.? I get a lot of comments on how unusually clean and consistent the repeater sounds.
My plan is to add a Quantar receiver and transmitter, although the home brewed receiver, which was originally built in 1974 and recently updated, is a fairly high performance receiver and can perform better than Mt. Wilson will allow.? I intend to feed the QUANTAR transmitter from the Optimod and keep my 1960 vintage controller, which sometimes makes noise like a Pachinko machine.? It has personality and sounds good.? Besides, I'm having a great time doing all this stuff.? To each their own.
I'm presently fighting intermittent power line noise which is believed to be coming from the 37,000 volt line coming up the mountain very near our location.? There is also an intermittent intermod problem involving our own transmitter and there's no audio, not even ours, to give a clue as to what the other signal/s might be, just narrow band noise when it happens.? It comes and goes like flipping a switch on and off.? I suspect a transmitter that's spewing wide band noise.? I've sat there with a spectrum analyzer till I'm blue in the face.? It doesn't want to happen when I'm there.? Why is that?
You can go to and look up W6MEP to see a picture of the repeater as it is now and how it looked when Art, W6MEP built his amazing contraption back in the 1950's.? You can also go to to see my first repeater and the silliness I went through in having a good time.
I do appreciate the comments and I know where you're coming from, but I also know where I'm going and still remain a good neighbor to adjacent channel repeaters.
Thank you for putting up with me.
Burt, K6OQK
|
I've done flat audio in the pass but always use a RC filter to roll off above 3-4khz...no need to go higher as the energy in that area is QUITE low and not needed..I've made GE MVPs rptrs with flat audio and FM on the exciter where it coupled to an ACC RC850 passed Alinco Digital with no problem...had to back off the radio deviation a little...it would clip thru the rptr at high deviation..
I've ran Quantars in flat audio mode using the RSS settings and found great results..but I would never use 5kHz audio b/w...the Carson rule of B/W tells me not to anyway ..it exceeds 16-20K easily.
I am not only a ham but a LMR and Broadcast Engineer for the last 45+ yrs.. Yeah I read all about the early repeaters in Bill Pasternak's book and other sources...I like keeping up with history like that. :)?
BTW I hate the idiots on HF trying HIFI SSB...WE ARE NOT broadcasters...makes me smdh
Just saying..
Chris WB5ITT?
On Mon, Oct 24, 2022, 11:55 PM Burt K6OQK < biwa@...> wrote: Ok guys...
You bring up a lot of interesting points, but nothing new to me.? Let me say that I've been in the 2-Meter repeater business for over 60 years.? I've always prided myself in good performance and good audio quality.? To me, and to many others, 300-3000 Hz audio doesn't cut it.? As it was said, this is Amateur Radio.? :)
The reason I want to access the wide band audio is to stay away from the typical narrow sound of many repeaters.? If you're in the southern California area, take a listen to the W6MEP 2-Meter repeater on 147.24 MHz.? It's very compatible with all 5 kHz dev radios, commercial and others.? The audio out of the completely home brewed receiver is wide band - 50 Hz to a little over 6 kHz? There is a very narrow P.L. notch filter in the controller.? The transmitter is direct FM. The modulation index is barely 1.? I do have audio processing in the system in the way of an Orban FM 8100A Optimod. (I do have the stereo turned off.) I have a low pass filter between the output of the processing and the input to the modulator.? The deviation is 4-4.5 kHz and is very consistent without sucking up noise between words.? The repeater is very transparent except that the transmitted audio is pretty consistent.? I get a lot of comments on how unusually clean and consistent the repeater sounds.
My plan is to add a Quantar receiver and transmitter, although the home brewed receiver, which was originally built in 1974 and recently updated, is a fairly high performance receiver and can perform better than Mt. Wilson will allow.? I intend to feed the QUANTAR transmitter from the Optimod and keep my 1960 vintage controller, which sometimes makes noise like a Pachinko machine.? It has personality and sounds good.? Besides, I'm having a great time doing all this stuff.? To each their own.
I'm presently fighting intermittent power line noise which is believed to be coming from the 37,000 volt line coming up the mountain very near our location.? There is also an intermittent intermod problem involving our own transmitter and there's no audio, not even ours, to give a clue as to what the other signal/s might be, just narrow band noise when it happens.? It comes and goes like flipping a switch on and off.? I suspect a transmitter that's spewing wide band noise.? I've sat there with a spectrum analyzer till I'm blue in the face.? It doesn't want to happen when I'm there.? Why is that?
You can go to and look up W6MEP to see a picture of the repeater as it is now and how it looked when Art, W6MEP built his amazing contraption back in the 1950's.? You can also go to to see my first repeater and the silliness I went through in having a good time.
I do appreciate the comments and I know where you're coming from, but I also know where I'm going and still remain a good neighbor to adjacent channel repeaters.
Thank you for putting up with me.
Burt, K6OQK
|
Don't know about you men, but at 79 yrs old my hearing aides make all, especially Motorola speakers sound more intelligible, much less muffled, and because of? the aide's high frequency pre-emphasis, audio at 3KHz now sounds plenty crisp and clear!
John W1GPO
On 10/25/2022 12:55 AM Burt K6OQK <biwa@...> wrote:
Ok guys...
You bring up a lot of interesting points, but nothing new to me.? Let me say that I've been in the 2-Meter repeater business for over 60 years.? I've always prided myself in good performance and good audio quality.? To me, and to many others, 300-3000 Hz audio doesn't cut it.? As it was said, this is Amateur Radio.? :)
The reason I want to access the wide band audio is to stay away from the typical narrow sound of many repeaters.? If you're in the southern California area, take a listen to the W6MEP 2-Meter repeater on 147.24 MHz.? It's very compatible with all 5 kHz dev radios, commercial and others.? The audio out of the completely home brewed receiver is wide band - 50 Hz to a little over 6 kHz? There is a very narrow P.L. notch filter in the controller.? The transmitter is direct FM. The modulation index is barely 1.? I do have audio processing in the system in the way of an Orban FM 8100A Optimod. (I do have the stereo turned off.) I have a low pass filter between the output of the processing and the input to the modulator.? The deviation is 4-4.5 kHz and is very consistent without sucking up noise between words.? The repeater is very transparent except that the transmitted audio is pretty consistent.? I get a lot of comments on how unusually clean and consistent the repeater sounds.
My plan is to add a Quantar receiver and transmitter, although the home brewed receiver, which was originally built in 1974 and recently updated, is a fairly high performance receiver and can perform better than Mt. Wilson will allow.? I intend to feed the QUANTAR transmitter from the Optimod and keep my 1960 vintage controller, which sometimes makes noise like a Pachinko machine.? It has personality and sounds good.? Besides, I'm having a great time doing all this stuff.? To each their own.
I'm presently fighting intermittent power line noise which is believed to be coming from the 37,000 volt line coming up the mountain very near our location.? There is also an intermittent intermod problem involving our own transmitter and there's no audio, not even ours, to give a clue as to what the other signal/s might be, just narrow band noise when it happens.? It comes and goes like flipping a switch on and off.? I suspect a transmitter that's spewing wide band noise.? I've sat there with a spectrum analyzer till I'm blue in the face.? It doesn't want to happen when I'm there.? Why is that?
You can go to and look up W6MEP to see a picture of the repeater as it is now and how it looked when Art, W6MEP built his amazing contraption back in the 1950's.? You can also go to to see my first repeater and the silliness I went through in having a good time.
I do appreciate the comments and I know where you're coming from, but I also know where I'm going and still remain a good neighbor to adjacent channel repeaters.
Thank you for putting up with me.
Burt, K6OQK
|
Jim, Thanks for your reply, and no, for some reason I did not see it earlier.? Are pins 9 & 34 a balanced pair?? How are they coupled in so as to have wide band audio? Electronically balanced, transformer, or each and unbalanced input?? I had seen those on another sheet and wasn't sure if they were data only and not capable of passing analog audio. Thanks, Burt, K6OQK
Then you did not see my reply.
The general transmit input is uses for simulcast. It passes DC to 10 KHz with no issues.
Connector 17, (50 pin telco)Pins 9 and 34
|
Hi Chris, Thanks for your comments and observations. On my repeater... no, I don't run the audio out to 5 kHz, but at the same time I don't have the sharp 2.5 or 3 kHz cutoff that many systems have.? I've learned over the years that if you're running through various pieces of equipment that have the same roll off or cutoff, you'll have ringing.? All of my system, and it is a stand alone repeater, and not tied to other systems, is wideband audio.? The audio is only "band-stopped" just prior to going into the modulator, But at the same time, I don't want that to be a sharp cutoff.? I do regularly monitor my occupied bandwidth, and only once have I had a complaint from a neighbor which I immediately took care of by lowering the deviation a tad.? That was caused by a previous mis-adjustment on my part. As far as running "flat audio," not sure what that means as there have been so many opinions on that term.? In the case of my system, I de-emphasize the audio out of the receiver so that I'm only dealing with "flat audio" from all my sources and then pre-emphasizing the audio just ahead of the modulator.? Keep in mind, the modulator is direct FM. Regarding two-way radio, pre and de-emphasis is always a compromise, as there really is no common standard and each manufacturer seems to have their own standard.? Even in the case of phase modulation, which has it's own natural pre-emphasis - the breaking point, if you will, is different between various equipment manufacturers.? It may not be very scientific, but I use a pot to adjust de-emphasis and adjust to what sounds pleasant.? It's a compromise. Anyway, it is "Ham Radio" and thankfully we are not tied to the two-way business "standards".? We can strive to make things sound pleasant and at the same time use good engineering practices.? I do not bow to the Motorola gods and I don't speak Motorolaese.? :) I'm sure we'll have more discussion on this, which is a good and pleasant thing. Burt, K6OQK
I've done flat audio in the pass but always use a RC filter to roll off above 3-4khz...no need to go higher as the energy in that area is QUITE low and not needed..I've made GE MVPs rptrs with flat audio and FM on the exciter where it coupled to an ACC RC850 passed Alinco Digital with no problem...had to back off the radio deviation a little...it would clip thru the rptr at high deviation..
?
I've ran Quantars in flat audio mode using the RSS settings and found great results..but I would never use 5kHz audio b/w...the Carson rule of B/W tells me not to anyway ..it exceeds 16-20K easily.
?
I am not only a ham but a LMR and Broadcast Engineer for the last 45+ yrs..
Yeah I read all about the early repeaters in Bill Pasternak's book and other sources...I like keeping up with history like that. :)?
?
BTW I hate the idiots on HF trying HIFI SSB...WE ARE NOT broadcasters...makes me smdh
?
Just saying..
?
?
Chris
WB5ITT
|
At 10/25/2022 06:20 AM, John wrote: Don't know about you men, but at 79 yrs old my hearing aides make all, especially Motorola speakers sound more intelligible, much less muffled, and because of the aide's high frequency pre-emphasis, audio at 3KHz now sounds plenty crisp and clear!
John W1GPO I'm 59 & my hearing is fine, yet I also prefer to go higher than 3 kHz on my repeat audio. I maintain several XPR8300/8400 repeaters set to flat unsquelch audio to give them the best frequency response possible. Unfortunately that is only 0-3.1 kHz or so, as the radio internally filters both the TX & RX audio down to that. Passing audio below 300 Hz does give them more realistic sounding audio that all the users say they much prefer (I either pass the users' PL, or strip it via a notch filter & re-encode), but the 3 kHz LPF just makes them sound mushy. If there was any way to bypass those LPFs I would. The TX might be possible via a method similar to what Burt is proposing to do with the Quantar, but the RX with its digital back end is hopeless. Bob NO6B
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At 10/25/2022 05:35 AM, you wrote: I've done flat audio in the pass but always use a RC filter to roll off above 3-4khz...no need to go higher as the energy in that area is QUITE low and not needed..I've made GE MVPs rptrs with flat audio and FM on the exciter where it coupled to an ACC RC850 passed Alinco Digital with no problem...had to back off the radio deviation a little...it would clip thru the rptr at high deviation..
I've ran Quantars in flat audio mode using the RSS settings and found great results..but I would never use 5kHz audio b/w...the Carson rule of B/W tells me not to anyway ..it exceeds 16-20K easily. The above two paragraphs contradict each other: if the spectral energy above 3 kHz is "QUITE low", then that spectrum will not be deviating the TX anywhere near 5 kHz, hence the BW will not be "16-20K". This is probably why I can tune my TYT TH-9800 15 kHz away from the W6MEP 147.240 repeater & listen to a repeater on 147.225 some 50+ miles away with no interference. In the end that is all that matters. Bob NO6B
|
I agree with you, Bob, that most important of anything is a post limiter filter that will roll off as steeply as practical above 3KHz, with a sharp knee so that below say 2800 is not affected. Seems that the problem usually lies in that the usual analog receiver de-emphasis and transmitter pre-emphasis may match overall, but often have a peak audio pass through around the mid point of 1500 cps with roll off below even at pass through below 400 and above 2200 cps. The worst in our somewhat limited experience was the GE Mastr Pro, and the best flattness, the Kenwood TK8180. I suppose in an ideal setup an audio equilizer is inserted to get flat repeater throughput from say 200-3000 cps and you set the dev pot for the same dev in and out at around 2500 cps instead of 1000 cps, otherwise the dev limiter will clip the higher frequencies starting above maybe 2000 cps on full deviation, including squelch noise, thus making the repeater appear to have a lack of highs, not caused by the roll off in the splatter filter, rather selectively clipping at the higher frequencies.
John W1GPO
toggle quoted message
Show quoted text
On 10/25/2022 12:47 PM Bob Dengler via groups.io <no6b@...> wrote:
At 10/25/2022 05:35 AM, you wrote:
I've done flat audio in the pass but always use a RC filter to roll off above 3-4khz...no need to go higher as the energy in that area is QUITE low and not needed..I've made GE MVPs rptrs with flat audio and FM on the exciter where it coupled to an ACC RC850 passed Alinco Digital with no problem...had to back off the radio deviation a little...it would clip thru the rptr at high deviation..
I've ran Quantars in flat audio mode using the RSS settings and found great results..but I would never use 5kHz audio b/w...the Carson rule of B/W tells me not to anyway ..it exceeds 16-20K easily. The above two paragraphs contradict each other: if the spectral energy above 3 kHz is "QUITE low", then that spectrum will not be deviating the TX anywhere near 5 kHz, hence the BW will not be "16-20K". This is probably why I can tune my TYT TH-9800 15 kHz away from the W6MEP 147.240 repeater & listen to a repeater on 147.225 some 50+ miles away with no interference. In the end that is all that matters.
Bob NO6B
|
On the GE MASTR PRO, there are a couple of capacitors you need to remove to get the perfectly audio flat.?? This applies to the MASTR imperial as well.? The caps are C-16 and optionally, C-21.??
Andy
I agree with you, Bob, that most important of anything is a post limiter filter that will roll off as steeply as practical above 3KHz, with a sharp knee so that below say 2800 is not affected. Seems that the problem usually lies in that the usual analog receiver de-emphasis and transmitter pre-emphasis may match overall, but often have a peak audio pass through around the mid point of 1500 cps with roll off below even at pass through below 400 and above 2200 cps. The worst in our somewhat limited experience was the GE Mastr Pro, and the best flattness, the Kenwood TK8180. I suppose in an ideal setup an audio equilizer is inserted to get flat repeater throughput from say 200-3000 cps and you set the dev pot for the same dev in and out at around 2500 cps instead of 1000 cps, otherwise the dev limiter will clip the higher frequencies starting above maybe 2000 cps on full deviation, including squelch noise, thus making the repeater appear to have a lack of highs, not caused by the roll off in the splatter filter, rather selectively clipping at the higher frequencies.
John W1GPO
> On 10/25/2022 12:47 PM Bob Dengler via <no6b=[email protected]> wrote:
>
>?
> At 10/25/2022 05:35 AM, you wrote:
> >I've done flat audio in the pass but always use a RC filter to roll off above 3-4khz...no need to go higher as the energy in that area is QUITE low and not needed..I've made GE MVPs rptrs with flat audio and FM on the exciter where it coupled to an ACC RC850 passed Alinco Digital with no problem...had to back off the radio deviation a little...it would clip thru the rptr at high deviation..
> >
> >I've ran Quantars in flat audio mode using the RSS settings and found great results..but I would never use 5kHz audio b/w...the Carson rule of B/W tells me not to anyway ..it exceeds 16-20K easily.
>
> The above two paragraphs contradict each other: if the spectral energy above 3 kHz is "QUITE low", then that spectrum will not be deviating the TX anywhere near 5 kHz, hence the BW will not be "16-20K".? This is probably why I can tune my TYT TH-9800 15 kHz away from the W6MEP 147.240 repeater & listen to a repeater on 147.225 some 50+ miles away with no interference.? In the end that is all that matters.
>
> Bob NO6B
>
>
>
>
|
Burt K6OQK
Chris Boone WB5ITT
Ken Arck AH6LE