Topics

Testing the Measurement Rcvr

Nigel Maund
 

Dear PHSNA testing community;

I am finally building the Measurement Receiver.

I wanted to ask advice on how to test/tune it as I build it in sections?

Here are my thoughts:

1) using the PHSNA, sweep the Xtal filter alone, and adjust the trim capacitors to get a flat response curve
2) add the 2n2222 Amplifier, to then see the sweep with a 20 dB gain

Next steps - how would I make sure that the Bridge Tee Diplexers are properly tuned?

Is it simple enough to wire up all the components and go for broke.
Or, is there a way to perhaps add in the Diplexer circuit and sweep it using a 3.2768 MHz (spare crystal) oscillator,. If I were to use a return loss bridge would this then give me some interesting way to use all the test components and actually see the Diplexer working?

I am thinking of how best to test each of the two boards separately, using the PHSNA and Power Meter, before connecting them together.

One final question: the schematic shows only one power connection circuitry (200 mA resettable fuse, shotkey diode) but both boards have PCB locations for this circuitry. Is it acceptable to simply wire one board with this circuitry, and jumper the 12 volts supply to the 2nd board. Or, do both boards need a 200 mA resettable fuse?

Thanks,
Nigel, Va2NM

Nick Kennedy
 

It's been 4+ years since I built mine, but I have some notes, fortunately.
Your idea of testing in sections is certainly a good one. I had to do a lot
of troubleshooting, although not generally due to the design or concept but
due to having a couple of bad mixers.

Also, I made a lot of changes so I had to be sure I'd done them correctly.
I used some 5.528 MHz crystals I had on hand so that changed the operating
frequency, the diplexer, the L-matches and so on.

Shooting through the crystal filter and its L-matchers before connecting to
the rest of the world is definitely a good idea. And since you have that
nice PHSNA instrument sitting there, why not?

I like to measure my critical component values pretty closely and also
simulate the circuits in LTspice, so sometimes I don't actually feel the
need to adjust trimmers. My notes say I pre-set my L-match trimmers to the
required value. But I could see plotting the filter curve and playing with
those trimmers until you got a nice flat response curve might be a good
thing.

I substituted an ERA-1SM for the ERA-3+ which changed other component
values a bit. It's easy enough to verify the gain of that stage acting
alone before installing the mixer.

For whatever reason(s), I didn't feel the need for so much oomph out of the
output amplifier so I changed the biasing to reduce standing current to
about 10 mA and didn't need a heat sink.

I did take a look through the diplexer before connecting it to the driving
and driven stages. I had already modeled it on LTspice and seen that, by
design, you don't get sharp peaks but you do get a constant load over a
wide range of frequencies. Which I guess is its function.

So getting back to testing in stages. Yes, especially on through-hole board
projects, it's a great idea. Sections can be hard to break apart after the
fact. And as I guess I've suggested already, you could easily build and
test separately the MMIC amplifier, the diplexer, the crystal filter plus
matchers and the output amp. Or combine the output amp with the filter.
This can be accomplished by holding off on installing the mixer until last,
testing the boards separately, and maybe keeping C15 out until you've
tested the filter and output amplifier separately.

On the fuse and blocking diode - your proposal to share them seems
reasonable. I don't remember exactly what I did there.

73 & good luck with the project,

Nick, WA5BDU

On Tue, Jan 1, 2019 at 6:40 PM Nigel Maund <maund.n@...> wrote:

Dear PHSNA testing community;

I am finally building the Measurement Receiver.

I wanted to ask advice on how to test/tune it as I build it in sections?

Here are my thoughts:

1) using the PHSNA, sweep the Xtal filter alone, and adjust the trim
capacitors to get a flat response curve
2) add the 2n2222 Amplifier, to then see the sweep with a 20 dB gain

Next steps - how would I make sure that the Bridge Tee Diplexers are
properly tuned?

Is it simple enough to wire up all the components and go for broke.
Or, is there a way to perhaps add in the Diplexer circuit and sweep it
using a 3.2768 MHz (spare crystal) oscillator,. If I were to use a return
loss bridge would this then give me some interesting way to use all the
test components and actually see the Diplexer working?

I am thinking of how best to test each of the two boards separately, using
the PHSNA and Power Meter, before connecting them together.

One final question: the schematic shows only one power connection
circuitry (200 mA resettable fuse, shotkey diode) but both boards have PCB
locations for this circuitry. Is it acceptable to simply wire one board
with this circuitry, and jumper the 12 volts supply to the 2nd board. Or,
do both boards need a 200 mA resettable fuse?

Thanks,
Nigel, Va2NM



Nigel Maund
 

Thanks for your feedback Nick,

I am intrigued as to why you may have changed to the 5.528 MHz frequency of operation?

And, also the decisions to go with lower amplifier output.

In researching other types of analyzers, I came across Ashar Farhan’s “Specan” design.

http://hfsignals.blogspot.com/p/specan-reboot-of-w7zoi.html
https://drive.google.com/file/d/0BzRNYeu10K6DdE1CSDVfZUdTdzg/view

He used a 12 MHz filter.
It occurs to me, that I could build the front stages of his design, and “tack them on” as front stages to the Measurement Receiver.

Let me start by getting the Measurement Receiver built (it has been, like 4 years on the back burner!).

Thanks and interested to hear from others that have implemented the Measurement Receiver.

Rgds,
Nigel
VA2NM

On Jan 2, 2019, at 8:31 PM, Nick Kennedy <kennnick@...> wrote:

It's been 4+ years since I built mine, but I have some notes, fortunately.
Your idea of testing in sections is certainly a good one. I had to do a lot
of troubleshooting, although not generally due to the design or concept but
due to having a couple of bad mixers.

Also, I made a lot of changes so I had to be sure I'd done them correctly.
I used some 5.528 MHz crystals I had on hand so that changed the operating
frequency, the diplexer, the L-matches and so on.

Shooting through the crystal filter and its L-matchers before connecting to
the rest of the world is definitely a good idea. And since you have that
nice PHSNA instrument sitting there, why not?

I like to measure my critical component values pretty closely and also
simulate the circuits in LTspice, so sometimes I don't actually feel the
need to adjust trimmers. My notes say I pre-set my L-match trimmers to the
required value. But I could see plotting the filter curve and playing with
those trimmers until you got a nice flat response curve might be a good
thing.

I substituted an ERA-1SM for the ERA-3+ which changed other component
values a bit. It's easy enough to verify the gain of that stage acting
alone before installing the mixer.

For whatever reason(s), I didn't feel the need for so much oomph out of the
output amplifier so I changed the biasing to reduce standing current to
about 10 mA and didn't need a heat sink.

I did take a look through the diplexer before connecting it to the driving
and driven stages. I had already modeled it on LTspice and seen that, by
design, you don't get sharp peaks but you do get a constant load over a
wide range of frequencies. Which I guess is its function.

So getting back to testing in stages. Yes, especially on through-hole board
projects, it's a great idea. Sections can be hard to break apart after the
fact. And as I guess I've suggested already, you could easily build and
test separately the MMIC amplifier, the diplexer, the crystal filter plus
matchers and the output amp. Or combine the output amp with the filter.
This can be accomplished by holding off on installing the mixer until last,
testing the boards separately, and maybe keeping C15 out until you've
tested the filter and output amplifier separately.

On the fuse and blocking diode - your proposal to share them seems
reasonable. I don't remember exactly what I did there.

73 & good luck with the project,

Nick, WA5BDU


On Tue, Jan 1, 2019 at 6:40 PM Nigel Maund <maund.n@... <mailto:maund.n@...>> wrote:

Dear PHSNA testing community;

I am finally building the Measurement Receiver.

I wanted to ask advice on how to test/tune it as I build it in sections?

Here are my thoughts:

1) using the PHSNA, sweep the Xtal filter alone, and adjust the trim
capacitors to get a flat response curve
2) add the 2n2222 Amplifier, to then see the sweep with a 20 dB gain

Next steps - how would I make sure that the Bridge Tee Diplexers are
properly tuned?

Is it simple enough to wire up all the components and go for broke.
Or, is there a way to perhaps add in the Diplexer circuit and sweep it
using a 3.2768 MHz (spare crystal) oscillator,. If I were to use a return
loss bridge would this then give me some interesting way to use all the
test components and actually see the Diplexer working?

I am thinking of how best to test each of the two boards separately, using
the PHSNA and Power Meter, before connecting them together.

One final question: the schematic shows only one power connection
circuitry (200 mA resettable fuse, shotkey diode) but both boards have PCB
locations for this circuitry. Is it acceptable to simply wire one board
with this circuitry, and jumper the 12 volts supply to the 2nd board. Or,
do both boards need a 200 mA resettable fuse?

Thanks,
Nigel, Va2NM



Nick Kennedy
 

I went to the 5.528 MHz IF solely in the spirit of trying to use parts that
are in my junk box. It certainly has no advantage over the frequency chosen
by Jerry H.

Some of the other stuff I did is hard to explain now. Possibly I wanted to
not use a heat sink on the output amplifier. And I felt that the PHSNA has
plenty of dynamic range. It's definitely a good design as-is though.

Yes, Farhan's SPECAN is very interesting. Who wouldn't love to have a
spectrum analyzer? And he claims it's easy enough to build and not
expensive. Maybe that one should go on the stack.

73-

Nick, WA5BDU

On Thu, Jan 3, 2019 at 11:47 AM Nigel Maund <maund.n@...> wrote:

Thanks for your feedback Nick,

I am intrigued as to why you may have changed to the 5.528 MHz frequency
of operation?

And, also the decisions to go with lower amplifier output.

In researching other types of analyzers, I came across Ashar Farhan’s
“Specan” design.

http://hfsignals.blogspot.com/p/specan-reboot-of-w7zoi.html
https://drive.google.com/file/d/0BzRNYeu10K6DdE1CSDVfZUdTdzg/view

He used a 12 MHz filter.
It occurs to me, that I could build the front stages of his design, and
“tack them on” as front stages to the Measurement Receiver.

Let me start by getting the Measurement Receiver built (it has been, like
4 years on the back burner!).

Thanks and interested to hear from others that have implemented the
Measurement Receiver.

Rgds,
Nigel
VA2NM

On Jan 2, 2019, at 8:31 PM, Nick Kennedy <kennnick@...> wrote:

It's been 4+ years since I built mine, but I have some notes,
fortunately.
Your idea of testing in sections is certainly a good one. I had to do a
lot
of troubleshooting, although not generally due to the design or concept
but
due to having a couple of bad mixers.

Also, I made a lot of changes so I had to be sure I'd done them
correctly.
I used some 5.528 MHz crystals I had on hand so that changed the
operating
frequency, the diplexer, the L-matches and so on.

Shooting through the crystal filter and its L-matchers before connecting
to
the rest of the world is definitely a good idea. And since you have that
nice PHSNA instrument sitting there, why not?

I like to measure my critical component values pretty closely and also
simulate the circuits in LTspice, so sometimes I don't actually feel the
need to adjust trimmers. My notes say I pre-set my L-match trimmers to
the
required value. But I could see plotting the filter curve and playing
with
those trimmers until you got a nice flat response curve might be a good
thing.

I substituted an ERA-1SM for the ERA-3+ which changed other component
values a bit. It's easy enough to verify the gain of that stage acting
alone before installing the mixer.

For whatever reason(s), I didn't feel the need for so much oomph out of
the
output amplifier so I changed the biasing to reduce standing current to
about 10 mA and didn't need a heat sink.

I did take a look through the diplexer before connecting it to the
driving
and driven stages. I had already modeled it on LTspice and seen that, by
design, you don't get sharp peaks but you do get a constant load over a
wide range of frequencies. Which I guess is its function.

So getting back to testing in stages. Yes, especially on through-hole
board
projects, it's a great idea. Sections can be hard to break apart after
the
fact. And as I guess I've suggested already, you could easily build and
test separately the MMIC amplifier, the diplexer, the crystal filter plus
matchers and the output amp. Or combine the output amp with the filter.
This can be accomplished by holding off on installing the mixer until
last,
testing the boards separately, and maybe keeping C15 out until you've
tested the filter and output amplifier separately.

On the fuse and blocking diode - your proposal to share them seems
reasonable. I don't remember exactly what I did there.

73 & good luck with the project,

Nick, WA5BDU


On Tue, Jan 1, 2019 at 6:40 PM Nigel Maund <maund.n@... <mailto:
maund.n@...>> wrote:

Dear PHSNA testing community;

I am finally building the Measurement Receiver.

I wanted to ask advice on how to test/tune it as I build it in sections?

Here are my thoughts:

1) using the PHSNA, sweep the Xtal filter alone, and adjust the trim
capacitors to get a flat response curve
2) add the 2n2222 Amplifier, to then see the sweep with a 20 dB gain

Next steps - how would I make sure that the Bridge Tee Diplexers are
properly tuned?

Is it simple enough to wire up all the components and go for broke.
Or, is there a way to perhaps add in the Diplexer circuit and sweep it
using a 3.2768 MHz (spare crystal) oscillator,. If I were to use a
return
loss bridge would this then give me some interesting way to use all the
test components and actually see the Diplexer working?

I am thinking of how best to test each of the two boards separately,
using
the PHSNA and Power Meter, before connecting them together.

One final question: the schematic shows only one power connection
circuitry (200 mA resettable fuse, shotkey diode) but both boards have
PCB
locations for this circuitry. Is it acceptable to simply wire one board
with this circuitry, and jumper the 12 volts supply to the 2nd board.
Or,
do both boards need a 200 mA resettable fuse?

Thanks,
Nigel, Va2NM






Tony Jaques
 

Hi Nigel,
I am part way through doing a Specan and it would be interesting to communicate about it. But obviously the PHSNA group is not the place to do it. There does not seem to be a group, but for now I have just joined the BITX20 group in the hope that they might create a section.
Apologies toPHSNA. My only excuse is that I have built two - one with Gary's sweep mods.

Tony (G3PTD)

Dave
 

Tony:
  There is a Yahoo group


Spectrum Analyzer Projects

  It is mainly for the Scotty Spectrum Analyzer, but some general discussion also.

Dave - WB6DHW

On 1/9/2019 12:10 PM, Tony Jaques wrote:
Hi Nigel,
I am part way through doing a Specan and it would be interesting to communicate about it. But obviously the PHSNA group is not the place to do it. There does not seem to be a group, but for now I have just joined the BITX20 group in the hope that they might create a section.
Apologies toPHSNA. My only excuse is that I have built two - one with Gary's sweep mods.

Tony (G3PTD)



K5ESS
 

Check out the group at HBTE@groups.io. There is currently a discussion about a spec anal built mostly out of ebay modules and workable up to 2 GHz.
Mike
K5ESS

-----Original Message-----
From: PHSNA@groups.io [mailto:PHSNA@groups.io] On Behalf Of Dave
Sent: Wednesday, January 9, 2019 3:41 PM
To: PHSNA@groups.io
Subject: Re: [PHSNA] Testing the Measurement Rcvr

Tony:
There is a Yahoo group


Spectrum Analyzer Projects

It is mainly for the Scotty Spectrum Analyzer, but some general
discussion also.

Dave - WB6DHW



On 1/9/2019 12:10 PM, Tony Jaques wrote:
Hi Nigel,
I am part way through doing a Specan and it would be interesting to communicate about it. But obviously the PHSNA group is not the place to do it. There does not seem to be a group, but for now I have just joined the BITX20 group in the hope that they might create a section.
Apologies toPHSNA. My only excuse is that I have built two - one with Gary's sweep mods.

Tony (G3PTD)




Tony Jaques
 

Sorry it's been a few days.
Thank you to Dave and Mike. Both groups look interesting, especially the HBTE one.
Tony...