PHSNA & Measurement Receiver


Nick Kennedy
 

I've been working on an SSB exciter using my Si5351a programmed as an I/Q VFO and some circuits from EMRFD. I finally got my two boards all wired up. Hooked up an audio generator and my Si5351a I/Q VFO and took a listen on the K3. It sounded awful and I couldn't make heads or tails of the mass of carriers and/or spurs I was hearing. But that often happens when trying to use your receiver to evaluate something on the bench.

I remembered I had this Measurement Receiver thing - inspired by Hayward, I think and designed by W5JH and N5IB and I wrote the code for PHSNA to take and show the data. It can be kind of a poor man's spectrum analyzer and it seems to have enough resolution to separate carrier and sidebands when the modulation signal is 1000 Hz.

When I looked at the data in Excel it still seemed like a mess, but when I looked at the relative amplitudes maybe it's not all that bad. The harmonics of 1000 Hz may come from my audio generator or might come from my circuit but they're not too bad except I don't know why the 3000 Hz one on the USB side is so large.

I haven't tried adjusting my sideband balance control yet, because I'm not sure how to assess the effect in real time.

That Measurement Receiver function in PHSNA hasn't gotten a lot of work due to the small number of users. (Am I the only one?) It doesn't do real time plotting, so I had to take the CSV and plot it in Excel. Not difficult though.

An image of the plot is attached.

73-

Nick, WA5BDU


Ted KX4OM
 

Nick,

Keep it up! I think those of us who have built the measurement receiver are starved for working ideas to play with. When I built it, I assumed the initial use would to inject an LO to a mixer such as an SBL-1 to move an RF signal down to the measurement receiver for analysis. Sort of like the idea from old QSTs to mix an RF frequency down to a limited bandwidth scope. I would think that the IF crystal filtering in the measurement receiver would do a pretty good job for something like that, and we would be able to see the frequencies like you have done with your experiment. I need a bit more of the concepts to work with, but I am interested in what you are doing.

Ted, KX4OM


William R Maxwell
 

I agree with ted, please keep working on this. My receiver is still awaiting assembly but it is on the task list.

Bill, VK7MX

On 27/5/20 6:56 am, Ted KX4OM wrote:
Nick,

Keep it up! I think those of us who have built the measurement receiver are starved for working ideas to play with. When I built it, I assumed the initial use would to inject an LO to a mixer such as an SBL-1 to move an RF signal down to the measurement receiver for analysis. Sort of like the idea from old QSTs to mix an RF frequency down to a limited bandwidth scope. I would think that the IF crystal filtering in the measurement receiver would do a pretty good job for something like that, and we would be able to see the frequencies like you have done with your experiment. I need a bit more of the concepts to work with, but I am interested in what you are doing.

Ted, KX4OM


wb6ogd
 

If you guys haven't built your receiver yet...
The main purpose of the receiver is just to be a simple spectrum analyzer, if I am not mistaken.
You may want to join the HBTE HomeBrewTestEquipment group.
Subscribe: HBTE+subscribe@groups.io <mailto:HBTE+subscribe@groups.io>

Erik, PD0EK, has a great simple design for a 0-200MHz spectrum analyzer, built with ebay modules
for about $35.  Mine is still in the proto stage but works amazingly well.  Goes right there along
with my PHSNA as most used test equipment.
His project is called tinySA.  It uses an Arduino(or similar) to control two Si4432 modules.
73,
Gary
WB6OGD

On 5/26/2020 3:10 PM, William R Maxwell wrote:
I agree with ted, please keep working on this. My receiver is still awaiting assembly but it is on the task list.

Bill, VK7MX

On 27/5/20 6:56 am, Ted KX4OM wrote:
Nick,

Keep it up! I think those of us who have built the measurement receiver are starved for working ideas to play with. When I built it, I assumed the initial use would to inject an LO to a mixer such as an SBL-1 to move an RF signal down to the measurement receiver for analysis. Sort of like the idea from old QSTs to mix an RF frequency down to a limited bandwidth scope. I would think that the IF crystal filtering in the measurement receiver would do a pretty good job for something like that, and we would be able to see the frequencies like you have done with your experiment. I need a bit more of the concepts to work with, but I am interested in what you are doing.

Ted, KX4OM



William R Maxwell
 

Thanks for that suggestion, Gary. I actually joined that group at the weekend but as yet, haven't had the time to read into the tinySA project.

Bill, VK7MX

On 27/5/20 9:27 am, wb6ogd wrote:
If you guys haven't built your receiver yet...
The main purpose of the receiver is just to be a simple spectrum analyzer, if I am not mistaken.
You may want to join the HBTE HomeBrewTestEquipment group.
Subscribe: HBTE+subscribe@groups.io <mailto:HBTE+subscribe@groups.io>

Erik, PD0EK, has a great simple design for a 0-200MHz spectrum analyzer, built with ebay modules
for about $35.  Mine is still in the proto stage but works amazingly well.  Goes right there along
with my PHSNA as most used test equipment.
His project is called tinySA.  It uses an Arduino(or similar) to control two Si4432 modules.
73,
Gary
WB6OGD

On 5/26/2020 3:10 PM, William R Maxwell wrote:
I agree with ted, please keep working on this. My receiver is still awaiting assembly but it is on the task list.

Bill, VK7MX

On 27/5/20 6:56 am, Ted KX4OM wrote:
Nick,

Keep it up! I think those of us who have built the measurement receiver are starved for working ideas to play with. When I built it, I assumed the initial use would to inject an LO to a mixer such as an SBL-1 to move an RF signal down to the measurement receiver for analysis. Sort of like the idea from old QSTs to mix an RF frequency down to a limited bandwidth scope. I would think that the IF crystal filtering in the measurement receiver would do a pretty good job for something like that, and we would be able to see the frequencies like you have done with your experiment. I need a bit more of the concepts to work with, but I am interested in what you are doing.

Ted, KX4OM





Nick Kennedy
 

That’s very interesting, Gary. I’ll check it out.

Some of the brains behind nanoVNA are supposed to be working on an
inexpensive SA. That sounds interesting. And then there are people using
those DSP wideband dongles to do SA as well. I just wonder how well they
work and if their resolution allows you do look at different side bands and
so on.

Yes, the Measurement Receiver does function as a kind of simple SA. I’d
used it before to look at harmonics coming out of some of my boat anchors
and homebrew QRP transmitters. It did well for that. This application of
comparing the amplitudes of sideband and carrier is nice to have, but
there’s no fast sweep type functionality.

73-

Nick, WA5BDU

On Tue, May 26, 2020 at 6:27 PM wb6ogd <garywinblad@comcast.net> wrote:

If you guys haven't built your receiver yet...
The main purpose of the receiver is just to be a simple spectrum
analyzer, if I am not mistaken.
You may want to join the HBTE HomeBrewTestEquipment group.
Subscribe: HBTE+subscribe@groups.io <mailto:HBTE+subscribe@groups.io>

Erik, PD0EK, has a great simple design for a 0-200MHz spectrum analyzer,
built with ebay modules
for about $35. Mine is still in the proto stage but works amazingly
well. Goes right there along
with my PHSNA as most used test equipment.
His project is called tinySA. It uses an Arduino(or similar) to control
two Si4432 modules.
73,
Gary
WB6OGD

On 5/26/2020 3:10 PM, William R Maxwell wrote:
I agree with ted, please keep working on this. My receiver is still
awaiting assembly but it is on the task list.

Bill, VK7MX

On 27/5/20 6:56 am, Ted KX4OM wrote:
Nick,

Keep it up! I think those of us who have built the measurement
receiver are starved for working ideas to play with. When I built it,
I assumed the initial use would to inject an LO to a mixer such as an
SBL-1 to move an RF signal down to the measurement receiver for
analysis. Sort of like the idea from old QSTs to mix an RF frequency
down to a limited bandwidth scope. I would think that the IF crystal
filtering in the measurement receiver would do a pretty good job for
something like that, and we would be able to see the frequencies like
you have done with your experiment. I need a bit more of the concepts
to work with, but I am interested in what you are doing.

Ted, KX4OM







wb6ogd
 

Hi Nick,
They might be the ones working on the tinySA, they have a prototype tinySA that looks
just like a nanoVNA, screen included.  I stopped working on my PCB version since I can wait
to just buy theirs  ;-)
I don't think the tinySA has enough RBW to look at the sidebands but don't know for sure.
I have used it to look at harmonics and search for spurs.  It displays in real time on the PC
screen or you can add a small display.
73,
Gary
WB6GOD

On 5/26/2020 6:12 PM, Nick Kennedy wrote:
That’s very interesting, Gary. I’ll check it out.

Some of the brains behind nanoVNA are supposed to be working on an
inexpensive SA. That sounds interesting. And then there are people using
those DSP wideband dongles to do SA as well. I just wonder how well they
work and if their resolution allows you do look at different side bands and
so on.

Yes, the Measurement Receiver does function as a kind of simple SA. I’d
used it before to look at harmonics coming out of some of my boat anchors
and homebrew QRP transmitters. It did well for that. This application of
comparing the amplitudes of sideband and carrier is nice to have, but
there’s no fast sweep type functionality.

73-

Nick, WA5BDU


On Tue, May 26, 2020 at 6:27 PM wb6ogd <garywinblad@comcast.net> wrote:

If you guys haven't built your receiver yet...
The main purpose of the receiver is just to be a simple spectrum
analyzer, if I am not mistaken.
You may want to join the HBTE HomeBrewTestEquipment group.
Subscribe: HBTE+subscribe@groups.io <mailto:HBTE+subscribe@groups.io>

Erik, PD0EK, has a great simple design for a 0-200MHz spectrum analyzer,
built with ebay modules
for about $35. Mine is still in the proto stage but works amazingly
well. Goes right there along
with my PHSNA as most used test equipment.
His project is called tinySA. It uses an Arduino(or similar) to control
two Si4432 modules.
73,
Gary
WB6OGD

On 5/26/2020 3:10 PM, William R Maxwell wrote:
I agree with ted, please keep working on this. My receiver is still
awaiting assembly but it is on the task list.

Bill, VK7MX

On 27/5/20 6:56 am, Ted KX4OM wrote:
Nick,

Keep it up! I think those of us who have built the measurement
receiver are starved for working ideas to play with. When I built it,
I assumed the initial use would to inject an LO to a mixer such as an
SBL-1 to move an RF signal down to the measurement receiver for
analysis. Sort of like the idea from old QSTs to mix an RF frequency
down to a limited bandwidth scope. I would think that the IF crystal
filtering in the measurement receiver would do a pretty good job for
something like that, and we would be able to see the frequencies like
you have done with your experiment. I need a bit more of the concepts
to work with, but I am interested in what you are doing.

Ted, KX4OM





EB4APL
 

Another good option for a Poor Ham Spectrum Analyzer is using a SDR receiver. You have many choices, for example if you want V-UHF, there is the RTL Digital TV dongle that is being sold for $10 and it is supported by the most popular free software. The spectrum display con resolve 1 Hz so you can see the modulation sidebands fairly well; the amplitude absolute calibration is not easy to do, but the relative is good so you can measure sideband to carrier ratios, sideband asymmetry and suppression and splatter. Using the waterfall display you see off the air how bad some "linear amplifiers" are. Even I have seen a professional CW station whose key clicks invaded an aeronautical station.

If you want HF coverage the hardware is more expensive, but not too much. I successfully installed one of these TV dongles as a panadapter in a HF transceiver. This doubles as an HF spectrum analyzer with its limitations, but is adequate to check modulations, carrier hum and so.

I even sent several receiving reports to a big HF station, informing them of power supply hum without obtaining an acknowledge. Later I realized that it was not just hum, they were sending 100 Hz encrypted data on their carrier.

73 de Ignacio EB4APL

El 27/05/2020 a las 4:20, wb6ogd escribió:
Hi Nick,
They might be the ones working on the tinySA, they have a prototype tinySA that looks
just like a nanoVNA, screen included.  I stopped working on my PCB version since I can wait
to just buy theirs  ;-)
I don't think the tinySA has enough RBW to look at the sidebands but don't know for sure.
I have used it to look at harmonics and search for spurs.  It displays in real time on the PC
screen or you can add a small display.
73,
Gary
WB6GOD


On 5/26/2020 6:12 PM, Nick Kennedy wrote:
That’s very interesting, Gary.  I’ll check it out.

Some of the brains behind nanoVNA are supposed to be working on an
inexpensive SA. That sounds interesting. And then there are people using
those DSP wideband dongles to do SA as well. I just wonder how well they
work and if their resolution allows you do look at different side bands and
so on.

Yes, the Measurement Receiver does function as a kind of simple SA. I’d
used it before to look at harmonics coming out of some of my boat anchors
and homebrew QRP transmitters. It did well for that. This application of
comparing the amplitudes of sideband and carrier is nice to have, but
there’s no fast sweep type functionality.

73-

Nick, WA5BDU


On Tue, May 26, 2020 at 6:27 PM wb6ogd <garywinblad@comcast.net> wrote:

If you guys haven't built your receiver yet...
The main purpose of the receiver is just to be a simple spectrum
analyzer, if I am not mistaken.
You may want to join the HBTE HomeBrewTestEquipment group.
Subscribe: HBTE+subscribe@groups.io <mailto:HBTE+subscribe@groups.io>

Erik, PD0EK, has a great simple design for a 0-200MHz spectrum analyzer,
built with ebay modules
for about $35.  Mine is still in the proto stage but works amazingly
well.  Goes right there along
with my PHSNA as most used test equipment.
His project is called tinySA.  It uses an Arduino(or similar) to control
two Si4432 modules.
73,
Gary
WB6OGD

On 5/26/2020 3:10 PM, William R Maxwell wrote:
I agree with ted, please keep working on this. My receiver is still
awaiting assembly but it is on the task list.

Bill, VK7MX

On 27/5/20 6:56 am, Ted KX4OM wrote:
Nick,

Keep it up! I think those of us who have built the measurement
receiver are starved for working ideas to play with. When I built it,
I assumed the initial use would to inject an LO to a mixer such as an
SBL-1 to move an RF signal down to the measurement receiver for
analysis. Sort of like the idea from old QSTs to mix an RF frequency
down to a limited bandwidth scope. I would think that the IF crystal
filtering in the measurement receiver would do a pretty good job for
something like that, and we would be able to see the frequencies like
you have done with your experiment. I need a bit more of the concepts
to work with, but I am interested in what you are doing.

Ted, KX4OM





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