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Re: QUANTAR VHF Audio Interface...
Well,? an 8100 is nice, especially with the XT chassis lol,? but not everybody can afford an Optimod or Orban audio processor..... I have a 6300 but it's for sale... Kind of overkill for ham radio and my FM translator fell through so what the heck. My feeling is if somebody has a problem with their audio THEY need to fix it, not the repeater.... in my book, a repeater should do nothing to a user's audio except pass it as is. When I got my RC850, the first thing I did was pull out the AGC that was in there because I felt it was pumping the audio too much. And I never looked back. On Sat, Nov 5, 2022, 9:19 PM nj902 <nj0907@...> wrote: Burt, |
Re: QUANTAR VHF Audio Interface...
Burt,
Thanks for taking the time to prepare a detailed response explaining your measurement procedures and your audio processing. I also agree that variations in user level make it hard to understand some transmissions.? Motorola's 'analog repeater boost' somewhat compensates but at the cost of compressing some of the high frequencies.? When done well as you have, audio processing can offer an enhanced user experience. ? I look forward to seeing any test result images that you can share. 73 |
Re: QUANTAR VHF Audio Interface...
Gang,
Please understand, my intention to transmit what has been refereed to as wideband audio is not to be HiFi, but to be something better than typical "telephone quality" audio.? I do not feel that I'm a part of the "government" where I can simply repeal the Laws of Physics that don't suit my needs - although I've tried. For occupied bandwidth measurements I use an Anritsu MS2721B spectrum analyzer.? I set the span to 100 kHz, the RBW (Resolution Bandwidth) to 100 Hz, and VBW (Video Bandwidth) to 30 kHz, and also use peak store.? With the repeater in use that has a mix of fully quieting and noisy signals I let the analyzer sweep for 10 minutes or longer.? It's best if I make these measurements at the sample out of the transmitter, but I can get a fairly good representation of reality from home. W6MEP runs 4 to 4.2 kHz peak deviation.? In the next few days I will post some spectrographs of the W6MEP repeater's occupied bandwidth.? In the meantime, I invite anyone in the range of the repeater to make occupied bandwidth measurements and show me where we are exceeding the limits imposed by good engineering, TASMA or any other coordinating group.? We do have a system that operates with its output 15 kHz below us and due to a deviation misadjustment on my part they were justifiably complaining about some interference.? Since I corrected the deviation they have not complained. So, what am I using for processing?? I'm using an ORBAN 8100A, an FM broadcast processor.? A few people have gotten up in arms over this, so yes, this is a stereo processor with a stereo generator in it.? I have the stereo generator disabled which kills the stereo pilot and L-R sub channel.? It provides the following: Audio AGC, peak limiting, a protection peak limiter,(not clipping) and pre-emphasis.? Granted, the pre-emphasis is 75 usec, not the typical communications whatever pre-emphasis.? It's essentially flat from 50 Hz to 1 kHz and then begins a 6dB/Octave pre-emphasis boost above 1 kHz.? Between the processor output and the Direct FM Varactor modulator of the transmitter I have a 5 kHz low pass filter that's pretty steep.? Here's an important factor to be aware of: the limiter and protection limiter are "pre-emphasis aware."? This means that it anticipates pre-emphasized modulating frequency verses deviation and, for lack of a better way to put it, it keeps the deviation from climbing at higher frequencies.? On noisy signals, squelch tails, or just plain blowing squelch, it holds the deviation to set parameters. The audio AGC has a fairly fast attack, which is adjustable, and a fairly slow release, which is also adjustable. What the AGC doesn't catch on attack, the limiter portion will catch. It's also gated, which means that when a quieting station stops talking, the AGC release stops and remains where it stopped until audio returns. A lot of us Hams speak right up in one sentence and then mumble in the next. Set up this way you don't hear it pumping up audio between words, sentences or other pauses in speech.? On noisy signals it's barely noticeable. One of the things about having the 75 usec preempahsis is that it allows the low end to be there.? It's not pushed or boosted, but it's not lost. The W6MEP repeater sounds clean and what comes in is what comes out, with the exception that the audio level is pretty consistent, even when screaming or mumbling in the mic. There are some that disagree, telling me I'm bringing up the noise when the audio expands.? Well, yes, but to hear someone that's only deviation a half kHz into a repeater, you have to turn up the audio if you want to hear them, and in doing so you're turning up not only any noise coming in to the repeater, but any noise between you and the repeater - Is that any better?? I get a lot of compliments on the fact that the W6MEP is easy to listen to; users don't have to turn the audio up and down, and it's clean sounding. I hope the above epistle gives a little insight into how the W6MEP repeater audio is controlled. There will be more. Burt, K6OQK nj902 Nov 4 ? #195367??
Burt's intention to transmit wideband audio in the interest of increased clarity or voice 'fidelity' prompted several people to express concern about the resulting signal bandwidth - especially on 2 meters in locations with 15 kHz channel spacing.
?
Burt replied: "I do regularly monitor my occupied bandwidth"
?
This is an excellent topic.? Burt, In the interest of sharing your knowledge and expertise with less experienced members of the group, could you provide a description of the process you use, equipment required,?and how to interpret the results in the context of not interfering with adjacent channel operations.? It would also be helpful if you could post an image or two... |
Re: VHF MTR2000 Poor Receive Performance
开云体育Okay-
From the graph - I'd guess the directional coupler is a -20dB model.? And - it looks like you're getting the expected directivity and RL trace that I would have expected - considering I don't know quality of the load of the exact value of the DC. As such - and from your other graphs of a different post, it would seem your receiver isn't tuned properly.? And if it is - it has terrible return loss at the desired receive frequency.? Enough so that notch depths are probably being degraded - to some degree.? Kevin On 11/5/2022 12:26 PM, Jared Smudde wrote: Here you go. |
Re: Occupied bandwidth - (was Windows 7 config)
Occupied bandwidth is an interesting topic.? For many of us - using an unmodified commercial transmitter - it's an 'academic' topic since the manufacturer has delt with it.
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That said, amateur radio is about experimentation.? Whether for voice or data applications, if the user is implementing the transmit audio processing, bandwidth is a serious consideration.
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Knowledge and understanding of bandwidth measurement procedures and results could be a weak area for many hams.
?
In his discussion about Quantar transmit audio, Burt said that he regularly monitors his occupied bandwidth.? I asked him to share his knowledge and expertise by explaining how he does occupied bandwidth measurement.
?
Hopefully this will promote an interesting an instructional discussion. |
Re: VHF MTR2000 Poor Receive Performance
Jared,
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Can you put a 50 ohm load on the directional coupler and show us what the return loss looks like for it across the same frequency range? Kevin On 11/5/2022 12:35 AM, Jared Smudde wrote:
I also went ahead and finally swept the receiver port for return loss and it wasn't pretty at all as shown below. |
Re: Yearly support request - Repeater Builder? website - W3KKC
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Van: [email protected] <[email protected]> namens hr2pac via groups.io <hr2pac@...>
Verzonden: vrijdag 4 november 2022 21:56 Aan: Repeater Builder <[email protected]> Onderwerp: Re: [repeater-builder] Yearly support request - Repeater Builder? website - W3KKC ?
Done!
Pedro Castillo
On Wednesday, November 2, 2022 at 07:15:28 PM CST, Kevin Custer <kuggie@...> wrote:
Hello everyone,
Once a year I ask for financial support to help defray the costs associated with the upkeep and furtherance of free repeater related help sites.? Repeater Builder continues to grow as we add information over the course of time.? With your donation, we'll be able to maintain the site, keeping it free.? Whether it be manuals or quality conversion articles, all information is provided free of charge.? There are literally thousands of .? Several manufacturers of repeater related equipment have gone out of business, but you can count on RB to continue to provide owners manuals and other information pertaining to these companies into the future.? Because of its size - even this group (on groups.io) is not free. If the Repeater Builder website or this group has helped you, would you please consider a small donation to help keep them going?? Donations via regular mail (address provided below) or PayPal are greatly appreciated! An online donation can be made by going to the and clicking on the PayPal Donate button: Or, by postal mail at: Kevin Custer 79 Cochise Court Palm Coast FL 32137 I'd like to thank my webmasters Matt Wagner N1ZYY and Mike Morris WA6ILQ who have stepped up in the absence of Bob Meister WA1MIK who passed away unexpectedly.? It is an enormous task to keep the site up to date.? I'd also like to thank the numerous authors and contributors who keep the articles and content coming - and of course my Email Group Moderators for their continued support. Repeater Builder? is a registered trademark in the United States of America, and is owned by me. is a company owned by me, where I sell some small project kits and products for (mainly) hams. is owned by Scott Zimmerman N3XCC and he is licensed for the use of the name in his business (since 2001). All of this sometimes causes confusion which can be sorted out here: Again - - Thank-You very much for your continued support! Comments or questions are always welcomed - please call or email. 73, Kevin W3KKC kuggie@... kevin@... (814) 313-4036 (reasonably hours eastern time) |
Re: VHF MTR2000 Poor Receive Performance
I also went ahead and finally swept the receiver port for return loss and it wasn't pretty at all as shown below.
Closeup on receiver frequency. The little hump at the actual receiver frequency concerns me. Move right or left of the hump and the return loss jumps to -13dBm. Wide shot from 136MHz-174MHz. Be return loss at 150MHz. |
Re: VHF MTR2000 Poor Receive Performance
So I manged to verify 2 things: My generator output level is accurate comparing it to my spectrum analyzer and the MTR has a receiver/alignment issue.
I took a freshly dealer aligned XPR 4550 VHF and tested its 12DB SINAD before and after the duplexer. It was testing about 0.17uV (-122dBm) at 12DB SINAD directly and about 0.2uV (-120dBm) after the duplexer. There were some adapters in use for the duplexer test that may slightly skew the numbers. |
Re: VHF MTR2000 Poor Receive Performance
Not going to lie, I haven't been able to figure out the Rigol enough to show the generator amplitude down past the -100dbm level so it really could be off. I need to figure out how to view it that low.
I mean, my test results showed the MTR at the receive port at 0.4uV (-115dBm) and 0.5uV (-113dBm) after the duplexer. I know the duplexer has 1.67dB of loss and then my jumper cables tested about 0.15dB loss so that explains the 2db difference. Even if the levels are off from the service monitor, it still shows at least the 2db loss that I've calculated using the spectrum analyzer. Didn't think of checking site noise floor, I'm running this at home before it ships off to the site. I do know I have VHF noise birdies from PoE cameras at my house. I was talking to the local repeater/rf guru about this and he asked my about my antenna setup I was using. I live in an HOA and can't have external antennas but I managed to slip a dual band magmount up on top of our disused metal chimney cap. I never had an issue with running UHF repeaters on that setup as there's probably enough metal up there for UHF. However, he said there's probably not enough metal/groundplane for VHF, which was a theory I thought of early on but discounted as it works great for VHF simplex but this is duplexer we're talking about. The repeater is on its way to the dealer, I can run a site desense test after I get it back or maybe grab another VHF radio and use it for testing. |
Re: Occupied bandwidth - (was Windows 7 config)
开云体育Guys (and gals),
Please go back and review the complete thread. The OP is using a "made for application" sound card that Scott Zimmerman designed ).? It's driven by digital data applications (in this instant case - VARA FM) that doesn't create audio (bandwidth or level) that results in a over occupied bandwidth situation.? Therefore, what Scott Z was/is recommending to the OP is technically correct for the application.? VARA FM runs comfortably at 2.25kHz deviation in a +/- 5kHz system.? There is no fear of wrecking anything here - even on 15kHz channel spacing. If what you thought was truly the case - I/he/we would agree with you, and be recommending the RB Version C was recently released, and includes optimizations to eliminate any possibility of post filter clipping and even further reduces clock leakage.? The big advantage of this module is it allows YOU to set the low-pass filters cut-off frequency and audio levels to the desired / allowed / legal occupied bandwidth - all with easy to set potentiometers.? This (or something like it) is what people should be using when taking discriminator / detector audio and putting it to the naked modulator. Comments and questions welcomed. Kevin W3KKC On 11/2/2022 12:51 PM, Burt K6OQK wrote: I have to agree with Chris on this.? Running raw discriminator audio directly into the modulator is going to cause problems.? You need "something" ahead of the modulator to control the maximum deviation.? This is one of the reasons I disagree with the idea of coming out of the discriminator, going directly into the modulator and setting the system for 5 kHz in and 5 kHz out. |
Re: BTECH AMP-220 Amplifier
On Fri, Nov 4, 2022 at 07:52 PM, Bob Dengler wrote:
If that's all that's wrong with it I'd be pleased. They're made for HTs, which normally will be TXing into a horrible match anyway so they're probably made to take fairly low return losses. I'm more concerned with what appears to be missing flange screws for the RF power MOSFET. Not too surprised: the only thing pulling heat off of the RFPA in the UV-5R is a piece of rubber wedged between the (plastic) transistor cap & diecast casing. Oh. Those screws were not missing.? There is a clip that looks coperish that goes over the MOSFET that has a thermal pad under it.? I unscrewed and removed the clip to get a clear view of the FET in order to record the part number in the photos. Maybe you're right, maybe there never was an intention to match the input impedance.? I about had a heart attack when the SWR meter went to 99. If I damaged the mobile radio that I was testing with, I would have been very upset. |
Re: QUANTAR VHF Audio Interface...
Burt's intention to transmit wideband audio in the interest of increased clarity or voice 'fidelity' prompted several people to express concern about the resulting signal bandwidth - especially on 2 meters in locations with 15 kHz channel spacing.
?
Burt replied: "I do regularly monitor my occupied bandwidth"
?
This is an excellent topic.? Burt, In the interest of sharing your knowledge and expertise with less experienced members of the group, could you provide a description of the process you use, equipment required,?and how to interpret the results in the context of not interfering with adjacent channel operations.? It would also be helpful if you could post an image or two
? |
Re: Need documentation for SS-32M tone encoder
Jim W7RY
开云体育I guess its set for 100.0.Glad you got the info. 73, Jim W7RY On 11/4/2022 7:02 PM, Jim W7RY via
groups.io wrote:
If its any help... --
Thanks and 73, Jim W7RY |
Re: Need documentation for SS-32M tone encoder
Jim W7RY
开云体育If its any help...The one in the picture is probably programed for 82.5 Hz. 73, Jim W7RY On 11/4/2022 6:10 PM, WD0FYF Gerald
wrote:
On Fri, Nov 4, 2022 at 12:01 PM, Nate Bargmann wrote: --
Thanks and 73, Jim W7RY |
Re: Need documentation for SS-32M tone encoder
Good news!
I sent an email to Communications Specialists this afternoon and received a reply from Randy with the instruction sheet for the SS-32M attached. I will attach it to this email. Mike, I suspect you can add it with the other SS-32 documentation. I did find that the power in and tone out wires were swapped as I suspected. Once that was fixed the board came to life. It was set for 100 Hz and I simply had to unsolder one pin and solder another to set it to 88.5 Hz. Thanks to all who replied. 73, Nate -- "The optimist proclaims that we live in the best of all possible worlds. The pessimist fears this is true." Web: Projects: GPG fingerprint: 82D6 4F6B 0E67 CD41 F689 BBA6 FB2C 5130 D55A 8819 |