Re: VHF MTR2000 Poor Receive Performance
Here you go. 
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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.
?
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.
?
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.
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Re: VHF MTR2000 Poor Receive Performance
Jared,
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
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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.
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.
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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
?
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. 
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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.
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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.
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Re: Occupied bandwidth - (was Windows 7 config)
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:
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Show quoted text
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.
Years ago when I was on the TASMA technical committee one of the
most frustrating problems I regularly faced was with people who
would do this.? In a lot of cases the squelch tail was measured
going out to 20 or more kHz of deviation, while popcorn and noise
from signals that were only partially quieting went out to almost
the same.? They don't understand.? It's just bad practice.
Burt, K6OQK
On Tue, Nov 1, 2022 at 10:29 AM, Chris Boone wrote:
I strongly disagree Scott...
That's a recipe for disaster. Feeding wide band unsquelched
noise to a modulator will cause the transmitter to over
deviate. Remember the squelch noise out of a discriminator is
half the bandwidth of the IF filter which means you have audio
at 7.5 khz + coming out of the receiver.. Anytime I run flat
audio, I always put a clipper/limiter circuit in line to
prevent over deviation, and also to limit the audio bandwidth
to 3 kilohertz maximum. Under FCC part 97 rules we are
required to make sure that we use good engineering practices.
Running raw discriminator audio straight into a transmitter
modulator without any processing violates that rule. I've done
that in microwave systems but that's a special case and you
have the bandwidth to do it. In the crowded VHF/UHF bands,
it's totally ludicrous to do so
?
Chris
WB5ITT
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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.
At least the board is well via'd - no unexpected ground loops here. Wonder if their true goal was to blow air through the PCB for cooling both sides?
Bob NO6B
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.
What's great is there looks to be tons of unused real estate for a pi network in the input path.? I may try my hand at removing the 0 Ohm resistor and putting in a small LC matching network in it's place. It will be new territory for me, but I look forward to giving it a try.
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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
?
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Re: Need documentation for SS-32M tone encoder
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...
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:
Hi all.
I have a friend that bought a radio with a Communications
Specialists
SS-32M that we need to change the tone. However, the only
documentation
I've been able to find on the Com Spec Web site and here on
the Repeater
Builder site is for the SS-32MP which seems to have a
different layout
and component count.
Does anyone have the document for the SS-32M?
TIA
73, Nate, N0NB
Nate,
Trying the file attachment again. If It's not here, you can find
it in the file section of this group. ts107.pdf
?Gerald wd0fyf
--
Thanks and 73, Jim W7RY
--
Thanks and 73, Jim W7RY
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Re: Need documentation for SS-32M tone encoder
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:
Hi all.
I have a friend that bought a radio with a Communications
Specialists
SS-32M that we need to change the tone. However, the only
documentation
I've been able to find on the Com Spec Web site and here on the
Repeater
Builder site is for the SS-32MP which seems to have a different
layout
and component count.
Does anyone have the document for the SS-32M?
TIA
73, Nate, N0NB
Nate,
Trying the file attachment again. If It's not here, you can find
it in the file section of this group. ts107.pdf
?Gerald wd0fyf
--
Thanks and 73, Jim W7RY
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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
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Re: QUANTAR VHF Audio Interface...
I am late to the party, having been unavoidably sidelined - don't ask. I think that this has been a good discussion with many thoughts and suggestions shared.
I also have some thoughts to share.? First, in case someone curious about Quantar transmit audio connections finds this thread, let's summarize.
?
The Quantar Instruction Manual, 68P81095E05-B, shows a number of interface configurations.? Typically, transmit audio is input through wireline #1.
This is an excellent choice.? It is a transformer isolated, balanced input that can be connected to balanced or unbalanced devices.? It comes preset to 600-ohm impedance
but can be changed to other values, including high impedance, with configuration jumpers.? A nominal level of -10 dBm will result in 60% deviation,
?
When using wireline #1 as a transmit input, PTT is configured with a wildcard command.?
Use of wirelines and wildcard functions requires that the station be equipped with a wireline interface board.? If you have a Quantar without a wireline board, your only choice for
I/O is the 6809/MRTI interface.
?
Also, since low frequency audio is not passed through the wireline input, tone coded squelch [PL/DPL] can either be encoded by the station, or - if it is desired to generate this externally
- input through J17-5 which must then be configured for Aux PL Audio.
The manual is somewhat unclear about the use of J17-5 so I did some research, and I prepared the attached document for clarification.
?
Finally, there is the Gen TX data +/- input which is intended for simulcast applications.? This input should be used with caution and requires the user to provide all transmit audio processing.
With this comes the risk of unacceptable transmit bandwidth.
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Re: BTECH AMP-220 Amplifier
At 11/4/2022 09:17 AM, you wrote: Well, curiosity got the better of me, so I went out and bought one of these to see what was inside. Honestly, I'm disappointed.? The construction is good enough for a $100 amp, but performance is off.I actually purchased 2. What I found is that both units have incredibly high input SWR.? They must have done a poor job of impedance matching the input. 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. At least the board is well via'd - no unexpected ground loops here. Wonder if their true goal was to blow air through the PCB for cooling both sides? Bob NO6B
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Re: VHF MTR2000 Poor Receive Performance
I have been away for a while, but I have tried to read all the messages in the discussion.
?
With respect to the 50-year-old service monitor, Jared has a modern spectrum analyzer and thus can verify generator amplitude to within a db.
?
A missing dB or 2 is a concern and should be resolved but I don't think that is enough to make a repeater "deaf"
?
Perhaps I missed something. What is the receiver's effective sensitivity with the system connected to the antenna vs. a load?
In other words, how much degradation is there due to the site noise floor?
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Re: Need documentation for SS-32M tone encoder
On Fri, Nov 4, 2022 at 12:01 PM, Nate Bargmann wrote:
Hi all.
I have a friend that bought a radio with a Communications Specialists
SS-32M that we need to change the tone. However, the only documentation
I've been able to find on the Com Spec Web site and here on the Repeater
Builder site is for the SS-32MP which seems to have a different layout
and component count.
Does anyone have the document for the SS-32M?
TIA
73, Nate, N0NB
Nate,
Trying the file attachment again. If It's not here, you can find it in the file section of this group. ts107.pdf ?Gerald wd0fyf
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Re: Need documentation for SS-32M tone encoder
On Fri, Nov 4, 2022 at 05:52 PM, WD0FYF Gerald wrote:
On Fri, Nov 4, 2022 at 12:01 PM, Nate Bargmann wrote:
Hi all.
I have a friend that bought a radio with a Communications Specialists
SS-32M that we need to change the tone. However, the only documentation
I've been able to find on the Com Spec Web site and here on the Repeater
Builder site is for the SS-32MP which seems to have a different layout
and component count.
Does anyone have the document for the SS-32M?
TIA
73, Nate, N0NB
Nate,
The attached file uses the same ic. Should be the same programming.
Gerald wd0fyf
Sorry file didn't make it
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Re: Need documentation for SS-32M tone encoder
On Fri, Nov 4, 2022 at 12:01 PM, Nate Bargmann wrote:
Hi all.
I have a friend that bought a radio with a Communications Specialists
SS-32M that we need to change the tone. However, the only documentation
I've been able to find on the Com Spec Web site and here on the Repeater
Builder site is for the SS-32MP which seems to have a different layout
and component count.
Does anyone have the document for the SS-32M?
TIA
73, Nate, N0NB
Nate,
The attached file uses the same ic. Should be the same programming. Gerald wd0fyf
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Re: Yearly support request - Repeater Builder? website - W3KKC
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)
|
Jared Smudde
Kevin Custer