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- Опубліковано 12 вер 2024
- Episode 607
Using the IF output and external mixer to increase the frequency range of a spectrum analyzer. Using my HP8558 spectrum analyzer to test a Bluetooth signal at 2.4GHz. Ever wonder why the first LO is on a front panel connector?
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/ imsaiguy
Cool little extension with that external mixer. Regarding the 200 MHz center frequency, your frequency span is 20 MHz, so it's sweeping from 190 - 210 MHz. If the original signal's center is at 2.45 GHz, then the LO must be spanning 2.24 - 2.26 GHz. If you have a frequency counter that goes up that high, set a zero span and see if the LO is operating in that range.
The manual indicates that the low end of the LO on the 8558B is 2.05 GHz, so you might be able to see a part of that span at 400 MHz.
yes, you are correct. It sweeps backwards though. 2.24-2.26 sweep 210-190
@@IMSAIGuy Yep. It's on the subtraction side of the mix, hence backwards. I didn't write it in such a way as to reflect that, though you're right that I probably should have.
Nice hetrodoyneing...
Thanks IMSAI Guy...
It's a clever hack.
From the HP Keysight 9018-05859 user and service manual, the first LO is 2.05 to 3.55 GHz is swept for 0 to 1.5 GHz input frequencies. Under normal operation, the internal mixer brings the signals down to the 2050 MHz first IF.
In your setup, the 1rst LO output and the WIFI/Bluetooth signal at 2.400 to 2.4835 GHz are mixed down to 350 to 433 Mhz and fed into the input. The internal mixer then mixes it down to the 2050 IF.
CF=200MHz --> LO=2.2GHz --> RF=2.4GHz---> bluetooth.
First time i see the LO output used! Very good
I was hoping the down converted spread frequency signal would of been demodulated...so we could hear that 96 dB S/N audio thru a little newer version LM386 with two channels...
I wonder if there is a chip...?
It sounds like you need to mix again and get to an empty area on FM broadcast ...then listen to your McInTosh receiver tuned and being played thru the JBL 3 ways...
Or send test signal through phone...go through the signal chain...measure the distortion like with you instrument
Maybe if the IC-705...general coverage reciever was turned in...
Its good to see...like how some earlier spectrum analyzer...used to cover like up 1.2 GHz...then go to 21 Gz...without changing the size or appearance that much..
My order S9...had the audio jack...and I would play or listen to the phone UA-cam audio or a Playlist by going into the RCA CD port on the Sony reciever heard through Altec Lansings.
I have also (4) CLS-215 Cerwin Vega tower speakers driven by two Crown 2002 XTI class D PA The pa are powerd by 2 12 VDC 8D bus batteries in series running a 3kW perfect sine wave inverter...24VDC to 120 VAC 60 Hz
It's just the little camping Karaoke ..but if someone wants to crank in...we been heard fainty a mile away...lol...
Usually one half playing at 5 watts average a side is plenty..one must not disrupt the animals trying to sleep...
.
Fred don't disrupt IMASI Guy and his teaching
Thanks IMSAI Guy
The old Tek 49X series analyzers had external mixers taking them well beyond the base range they operated at. Nice hack!
I do understand something about this spectrum analyzer. What does it output to the scope? What is the blue channel set to? Does this analyzer convert frequency sweep to analog amplitude signal with a fixed time base? How do you synchronize the horizontal scale, so that the readings are accurate?
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can you please go over how you connected the spec an to the oscope please. I like the way you are using your oscope screen and your spec an hardware to accomplish the video.
ua-cam.com/video/UnpmJsCdPVA/v-deo.htmlsi=SfvPm02VHtEBGnt-
You have some super cool videos, thank you for educating us. Why not to draw down on a piece of paper the signal flow of this setup and explain some mixer basics, would be easier to understand for most people.
Warm regards from Germany, Helmut
PS: Can you add the Link to the eBay mixer into the description would nee of interest.
Sorry the mixer was only one (used). Thanks for the recommendation of drawing the mixer stuff. I know that will help some. Where in Germany are you. My last job I traveled to Aachen twice a year.
@@IMSAIGuy I am from the Hannover region.
BTW: I got an used Agilent E4443 PSA SA where the Elcom S-1006A 3.6 Ghz phase locked oscillator output is defective, the output is -7 dB instead of +10. I believe the corroded band path is the problem. I am working on it in my spare time.
Is has a 1.8 GHz internal locked output which works correct, this goes with +20 dBm into a doubler (HMC188), this goes into a band path filter and finally into a MMIC Amplifier (Sirenza SNA-186?) which should produce +10 dB
It quite a challenge for me to repair it, even de-soldering parts is difficult because the metal around will dissipates all the heat. Maybe I should use a preheating station to bring it to permanent 150° C to use an airflow gun to de-solder it.
Regards Helmut
Good information. Which is the spectrum analyzer, the HP or the RIGOL sitting above it?
The spectrum analyzer is the unit below. It is designed to be a plug in for an HP oscilloscope I do not have. the upper unit is a Rigol oscilloscope being used as the display.
If you search on 8558B, I have several videos on this unit
Very neat.