Problem with HP 83623A 20 GHz sweep generator stepping up/down 100 Hz when not wanted.
I run a test over the weekend with a fellow radio ham. I transmitted 100 mW
or so at 10368.115 MHz from an HP 83623A 10 MHz to 20 GHz sweep generator
into a small horn antenna inside my lab.
He was able to receive me about 7 km away, although the signal was quite
week - it was 20 dB above the noise in a 2.9 Hz bandwidth.
What is odd, is that his transceiver + transverter combination indicates
the signal generator is shifting frequency up/down 100 Hz. This is not slow
drift, but a step change - see waterfall picture, where time is on the
vertical axis, and frequency is on the horizontal. Unfortunately I don't
know what the scale is on the vertical axis - I am trying to find out. The
frequency on the x-axis is not the true frequency, but that shown on an 2 m
amateur transceiver, so the true frequency is more than 10 GHz higher.
The step size on this HP sweeper is 1 kHz, so the 100 Hz up/down shift is
not due to a rotary encoder that might be just on the limit of two
frequencies. Both the internal oscillator and a GPS locked frequency
standard were used during this test. Going from internal to external
reference caused a 450 Hz step in frequency, but did not change this
up/down 100 Hz behavior. So the problem is certainly not the crystal in a
10 MHz reference oscillator, as two have been tried, one of which was
locked to GPS.
Does anyone have an idea what may cause this behavior?
Does anyone have any ideas on the best way to investigate this, given the
signal is at more than 10 GHz?
What I do not have is any other signal generator capable of operation at
10 GHz. The only other sig gen I have is a 30 MHz Stanford Research DS345
function generator.
I don't have a TI counter at the minute, but had an offer of $300 accepted
on eBay for a 5370B a couple of days back, so should have a TI counter
soon. (Yes, I have had an 5370B and SR620 in the past, but for various
reasons no longer have them). The 5370B at $300 was a lot cheaper than an
SR620.
Other equipment I have include
- 22 GHz spectrum analyzer
- 30 MHz signal generator
- 20 GHz VNA
but no other signal generator capable of anywhere near 10 GHz.
I do have a couple of double balanced mixers which have RF and IF inputs
that will take 10 GHz, and an IF output that will go from DC to 4 GHz.
Introducing a REALLY long delay might allow the steps to be seen, as the
frequency at the LO and RF inputs of the mixers will be different. But
that's not really practical, as I'd need an awfully long bit of coax.
The 20 GHz vector network analyzer, which could be pressed into service as
a poor (rich) mans microwave signal source, but I suspect the output of
that is quite dirty, as the output is generated from a step recovery diode.
I have not yet tested it on a spectrum analyzer, but the SA has quite a few
spurious signals, so I'm never exactly confident of the SA. But one thing
to possibly is
- Set sweep generator to 10.368 GHz
- Set sweep generator to 10.378 GHz, so there's a 10 MHz difference.
- Mix the VNA + sweeper down to 10 MHz using a double balanced mixer
- Compare the 10 MHz at the output of a mixer to that of a 10 MHz crystal.
Steps of 100 Hz should then be seen I guess.
Any better suggestions?
Someone had kindly given me a key to change the step size of the signal
generator from 1 kHz to 1 Hz. I've not applied that yet, as it is quite a
complex procedure. But the fact the step size of this is 1 kHz, but it is
shifting up/down 100 Hz, does not make sense. Especially given the unit is
capable of 1 Hz resolution, but HP decided to charge extra for 1 Hz steps.
Luckily this is just a software option.
I did wonder if the signal generator was incapable of output the exact
frequency needed, so it was stepped up/down periodically so it gave the
right number of cycles over a long duration. But again, the fact it can
step 1 Hz with just a software upgrade suggest that's not the case.
The radio ham that noticed this step change in frequency is well used to
listening on 10 GHz, and hearing beacons. So I think its reasonable to
assume that the problem is not his end, but my end.
Any thoughts, which do NOT include purchasing a second expensive 20 GHz
signal generator. They are around $10,000 each, so a bit out of my price
range.
Dave
On 21 December 2016 at 23:42, Dr. David Kirkby (Kirkby Microwave Ltd) <
drkirkby@kirkbymicrowave.co.uk> wrote:
But one thing to possibly is
- Set sweep generator to 10.368 GHz
- Set sweep generator to 10.378 GHz, so there's a 10 MHz difference.
I mean set the VNA to 10.378 GHz, so there's a 10 MHz difference between
the VNA and sweep generator.
Dave
Hi David:
Do you have a comb generator?
--
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
The lesser of evils is still evil.
-------- Original Message --------
I run a test over the weekend with a fellow radio ham. I transmitted 100 mW
or so at 10368.115 MHz from an HP 83623A 10 MHz to 20 GHz sweep generator
into a small horn antenna inside my lab.
He was able to receive me about 7 km away, although the signal was quite
week - it was 20 dB above the noise in a 2.9 Hz bandwidth.
What is odd, is that his transceiver + transverter combination indicates
the signal generator is shifting frequency up/down 100 Hz. This is not slow
drift, but a step change - see waterfall picture, where time is on the
vertical axis, and frequency is on the horizontal. Unfortunately I don't
know what the scale is on the vertical axis - I am trying to find out. The
frequency on the x-axis is not the true frequency, but that shown on an 2 m
amateur transceiver, so the true frequency is more than 10 GHz higher.
The step size on this HP sweeper is 1 kHz, so the 100 Hz up/down shift is
not due to a rotary encoder that might be just on the limit of two
frequencies. Both the internal oscillator and a GPS locked frequency
standard were used during this test. Going from internal to external
reference caused a 450 Hz step in frequency, but did not change this
up/down 100 Hz behavior. So the problem is certainly not the crystal in a
10 MHz reference oscillator, as two have been tried, one of which was
locked to GPS.
Does anyone have an idea what may cause this behavior?
Does anyone have any ideas on the best way to investigate this, given the
signal is at more than 10 GHz?
What I do not have is any other signal generator capable of operation at
10 GHz. The only other sig gen I have is a 30 MHz Stanford Research DS345
function generator.
I don't have a TI counter at the minute, but had an offer of $300 accepted
on eBay for a 5370B a couple of days back, so should have a TI counter
soon. (Yes, I have had an 5370B and SR620 in the past, but for various
reasons no longer have them). The 5370B at $300 was a lot cheaper than an
SR620.
Other equipment I have include
- 22 GHz spectrum analyzer
- 30 MHz signal generator
- 20 GHz VNA
but no other signal generator capable of anywhere near 10 GHz.
I do have a couple of double balanced mixers which have RF and IF inputs
that will take 10 GHz, and an IF output that will go from DC to 4 GHz.
Introducing a REALLY long delay might allow the steps to be seen, as the
frequency at the LO and RF inputs of the mixers will be different. But
that's not really practical, as I'd need an awfully long bit of coax.
The 20 GHz vector network analyzer, which could be pressed into service as
a poor (rich) mans microwave signal source, but I suspect the output of
that is quite dirty, as the output is generated from a step recovery diode.
I have not yet tested it on a spectrum analyzer, but the SA has quite a few
spurious signals, so I'm never exactly confident of the SA. But one thing
to possibly is
- Set sweep generator to 10.368 GHz
- Set sweep generator to 10.378 GHz, so there's a 10 MHz difference.
- Mix the VNA + sweeper down to 10 MHz using a double balanced mixer
- Compare the 10 MHz at the output of a mixer to that of a 10 MHz crystal.
Steps of 100 Hz should then be seen I guess.
Any better suggestions?
Someone had kindly given me a key to change the step size of the signal
generator from 1 kHz to 1 Hz. I've not applied that yet, as it is quite a
complex procedure. But the fact the step size of this is 1 kHz, but it is
shifting up/down 100 Hz, does not make sense. Especially given the unit is
capable of 1 Hz resolution, but HP decided to charge extra for 1 Hz steps.
Luckily this is just a software option.
I did wonder if the signal generator was incapable of output the exact
frequency needed, so it was stepped up/down periodically so it gave the
right number of cycles over a long duration. But again, the fact it can
step 1 Hz with just a software upgrade suggest that's not the case.
The radio ham that noticed this step change in frequency is well used to
listening on 10 GHz, and hearing beacons. So I think its reasonable to
assume that the problem is not his end, but my end.
Any thoughts, which do NOT include purchasing a second expensive 20 GHz
signal generator. They are around $10,000 each, so a bit out of my price
range.
Dave
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Can you use the VNA as a receiver? And determine whether the 100Hz shift is also seen on the VNA
On Dec 21, 2016, at 7:31 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkirkby@kirkbymicrowave.co.uk wrote:
On 21 December 2016 at 23:42, Dr. David Kirkby (Kirkby Microwave Ltd) <
drkirkby@kirkbymicrowave.co.uk> wrote:
But one thing to possibly is
- Set sweep generator to 10.368 GHz
- Set sweep generator to 10.378 GHz, so there's a 10 MHz difference.
I mean set the VNA to 10.378 GHz, so there's a 10 MHz difference between
the VNA and sweep generator.
Dave
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Dave Congratulations on 10 Ghz SSB.
Now to your question. I will fully believe you are seeing normal behavior
of the generators. Even if its dithering 100 Hz thats pretty amazing. Sweep
gens simply are not stable enough for narrow work like you are trying.
Now I am sure comments will prove me totally wrong.
But I don't think so. (Have been on 10G SSB over the years also. Only 60
watts plus. Nothing fancy. ;-) )
Regards
Paul
WB8TSL
On Wed, Dec 21, 2016 at 7:31 PM, Dr. David Kirkby (Kirkby Microwave Ltd) <
drkirkby@kirkbymicrowave.co.uk> wrote:
On 21 December 2016 at 23:42, Dr. David Kirkby (Kirkby Microwave Ltd) <
drkirkby@kirkbymicrowave.co.uk> wrote:
But one thing to possibly is
- Set sweep generator to 10.368 GHz
- Set sweep generator to 10.378 GHz, so there's a 10 MHz difference.
I mean set the VNA to 10.378 GHz, so there's a 10 MHz difference between
the VNA and sweep generator.
Dave
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/
mailman/listinfo/time-nuts
and follow the instructions there.
If it is any help, the 836XXA/B series are all capable of 1Hz resolution but are locked at 1KHz unless you enter the license key for option 008. So it could be software/firmware related.
Happy Merry;
Thomas Knox
From: time-nuts time-nuts-bounces@febo.com on behalf of Dr. David Kirkby (Kirkby Microwave Ltd) drkirkby@kirkbymicrowave.co.uk
Sent: Wednesday, December 21, 2016 4:42 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Problem with HP 83623A 20 GHz sweep generator stepping up/down 100 Hz when not wanted.
I run a test over the weekend with a fellow radio ham. I transmitted 100 mW
or so at 10368.115 MHz from an HP 83623A 10 MHz to 20 GHz sweep generator
http://www.keysight.com/en/pd-1000001862%3Aepsg%3Apro-pn-83623A/synthesized-sweeper-10-mhz-to-20-ghz-high-power?cc=GB&lc=eng
83623A Synthesized Sweeper, 10 MHz to 20 GHz, High Power [Obsolete] | Keysight (formerly Agilent’s Electronic Measurement)http://www.keysight.com/en/pd-1000001862%3Aepsg%3Apro-pn-83623A/synthesized-sweeper-10-mhz-to-20-ghz-high-power?cc=GB&lc=eng
www.keysight.com
The 83623A is no longer available, the replacement product is E8257D PSG analog signal generator.
into a small horn antenna inside my lab.
He was able to receive me about 7 km away, although the signal was quite
week - it was 20 dB above the noise in a 2.9 Hz bandwidth.
What is odd, is that his transceiver + transverter combination indicates
the signal generator is shifting frequency up/down 100 Hz. This is not slow
drift, but a step change - see waterfall picture, where time is on the
vertical axis, and frequency is on the horizontal. Unfortunately I don't
know what the scale is on the vertical axis - I am trying to find out. The
frequency on the x-axis is not the true frequency, but that shown on an 2 m
amateur transceiver, so the true frequency is more than 10 GHz higher.
The step size on this HP sweeper is 1 kHz, so the 100 Hz up/down shift is
not due to a rotary encoder that might be just on the limit of two
frequencies. Both the internal oscillator and a GPS locked frequency
standard were used during this test. Going from internal to external
reference caused a 450 Hz step in frequency, but did not change this
up/down 100 Hz behavior. So the problem is certainly not the crystal in a
10 MHz reference oscillator, as two have been tried, one of which was
locked to GPS.
Does anyone have an idea what may cause this behavior?
Does anyone have any ideas on the best way to investigate this, given the
signal is at more than 10 GHz?
What I do not have is any other signal generator capable of operation at
10 GHz. The only other sig gen I have is a 30 MHz Stanford Research DS345
function generator.
I don't have a TI counter at the minute, but had an offer of $300 accepted
on eBay for a 5370B a couple of days back, so should have a TI counter
soon. (Yes, I have had an 5370B and SR620 in the past, but for various
reasons no longer have them). The 5370B at $300 was a lot cheaper than an
SR620.
Other equipment I have include
- 22 GHz spectrum analyzer
- 30 MHz signal generator
- 20 GHz VNA
but no other signal generator capable of anywhere near 10 GHz.
I do have a couple of double balanced mixers which have RF and IF inputs
that will take 10 GHz, and an IF output that will go from DC to 4 GHz.
Introducing a REALLY long delay might allow the steps to be seen, as the
frequency at the LO and RF inputs of the mixers will be different. But
that's not really practical, as I'd need an awfully long bit of coax.
The 20 GHz vector network analyzer, which could be pressed into service as
a poor (rich) mans microwave signal source, but I suspect the output of
that is quite dirty, as the output is generated from a step recovery diode.
I have not yet tested it on a spectrum analyzer, but the SA has quite a few
spurious signals, so I'm never exactly confident of the SA. But one thing
to possibly is
- Set sweep generator to 10.368 GHz
- Set sweep generator to 10.378 GHz, so there's a 10 MHz difference.
- Mix the VNA + sweeper down to 10 MHz using a double balanced mixer
- Compare the 10 MHz at the output of a mixer to that of a 10 MHz crystal.
Steps of 100 Hz should then be seen I guess.
Any better suggestions?
Someone had kindly given me a key to change the step size of the signal
generator from 1 kHz to 1 Hz. I've not applied that yet, as it is quite a
complex procedure. But the fact the step size of this is 1 kHz, but it is
shifting up/down 100 Hz, does not make sense. Especially given the unit is
capable of 1 Hz resolution, but HP decided to charge extra for 1 Hz steps.
Luckily this is just a software option.
I did wonder if the signal generator was incapable of output the exact
frequency needed, so it was stepped up/down periodically so it gave the
right number of cycles over a long duration. But again, the fact it can
step 1 Hz with just a software upgrade suggest that's not the case.
The radio ham that noticed this step change in frequency is well used to
listening on 10 GHz, and hearing beacons. So I think its reasonable to
assume that the problem is not his end, but my end.
Any thoughts, which do NOT include purchasing a second expensive 20 GHz
signal generator. They are around $10,000 each, so a bit out of my price
range.
Dave
On 22 December 2016 at 03:17, paul swed paulswedb@gmail.com wrote:
Dave Congratulations on 10 Ghz SSB.
This was not a QSO at all. It was simply a one way transmission from a
signal generator at my end to a receiver at his end. No QSO was attempted.
Now to your question. I will fully believe you are seeing normal behavior
of the generators. Even if its dithering 100 Hz thats pretty amazing. Sweep
gens simply are not stable enough for narrow work like you are trying.
Now I am sure comments will prove me totally wrong.
But I find it a bit odd that HP would have a 1 Hz software option on this
instrument, if the instrument jumped up/down 100 Hz.
Now I don't yet have the 1 Hz option programmed in, and it might well
change the behavior completely, but I'd still like to find a way, if one
exists, of checking this with the equipment I have.
The signal generator is no longer supported, but I could try my luck seeing
if there are any known problems with this unit, or firmware upgrades
available - currently revision 29, May 1991.
But I don't think so. (Have been on 10G SSB over the years also. Only 60
watts plus. Nothing fancy. ;-) )
Regards
Paul
WB8TSL
60 W is clearly some setup. I also know a lot of people run portable stuff
on 10 GHz, where achieving frequency stability is more of a challenge,
although less so with GPS. But this is a laboratory instrument, from a
reputable manufacturer. I personally would not expected this behavior. I
actually purchased this very cheaply (£650 GBP, which would have been about
$900 at the time), but they are not cheap to buy now.
Dave
On 22 December 2016 at 01:35, Brooke Clarke brooke@pacific.net wrote:
Hi David:
Do you have a comb generator?
No.
Dave
On 22 December 2016 at 03:51, Tom Knox actast@hotmail.com wrote:
If it is any help, the 836XXA/B series are all capable of 1Hz resolution
but are locked at 1KHz unless you enter the license key for option 008. So
it could be software/firmware related.
Happy Merry;
Thomas Knox
I have the license key - not exactly via an official means I might add. I
would not be surprised if that changed the behavior in some way, but I'd
like to resolve this problem, if one exists, before the upgrade.
Dave
On Thu, 22 Dec 2016 12:39:27 +0000, you wrote:
But I find it a bit odd that HP would have a 1 Hz software option on this
instrument, if the instrument jumped up/down 100 Hz.
Now I don't yet have the 1 Hz option programmed in, and it might well
change the behavior completely, but I'd still like to find a way, if one
exists, of checking this with the equipment I have.
The signal generator is no longer supported, but I could try my luck seeing
if there are any known problems with this unit, or firmware upgrades
available - currently revision 29, May 1991.
...
Dave
I agree with Bill, maybe something is going on at the other end.
While I do not expect this sort of thing from HP, could they have
deliberately designed the sweep generator to include those 100 Hz
bumps unless the 1 HZ software option was purchased?
Like Paul, I would not expect the kind of stability you need from a
sweep generator but that 100 Hz jump is just weird. It does kind of
remind me of popcorn noise but without a time scale and a longer
record, it is difficult to tell.