Noise problem with TG at IF2

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gebowes
Posts: 48
Joined: Sat Apr 28, 2018 3:50 pm

Re: Noise problem with TG at IF2

Post by gebowes » Tue Feb 27, 2018 3:43 am

Hi Garry,
To tell you the truth, I had the same reaction when comparing the data sheets. Because each mixer is unique, I would suggest that you just try substituting the M1 J and see what your results are.
All it took for me was a few minutes of actual use to sell me on its merits.
  1. Due to the actual better isolation, the LO1 leakage (also know as the zero hump) was reduced in magnitude over 20dB. Possibly more important, the bandwidth of the zero hump narrowed significantly. It now goes into my noise floor (approx -110dBm) at about 1.5 kHz.
  2. A second benefit if reduced conversion loss with an improvement of about 5dB at 1MHz and 18 dBm at 2800MHz compared to the ADE-11X.
  3. The one negative I see is that it is far more important to reverse the R and I ports for high frequencies with the M1J than with the ADE-11X
Here are the results of one set of tests I made:
Test signal was the same but filters created different input magnitude depending on frequency. At the same frequency, the input signals were identical for both mixers.
I uploaded the test results to the files area (Graham's MSA folder) as ti seems that Yahoo lost the reply with the attachments.
Sorry if this got duplicated.
Graham

John Penwarden
Posts: 23
Joined: Sat Apr 28, 2018 6:49 pm

Re: Noise problem with TG at IF2

Post by John Penwarden » Tue Feb 27, 2018 8:39 am

Attachments :[/list]Hi Graham,
I rechecked my calibration at the low khz end and corrected the frequency calibration table accordingly.  Attached is the response of my MSA, standard Scottie, duplicating your 2Khz plot except my B/W is 0.5Khz and I am using my Wien AF oscillator.  I do seem to have a quite high  level zero hump but the 2Khz signal point is probably still usable for reasonable signal levels.  My noise level seems to be very similar to yours.
John

On Tuesday, 27 February 2018, 4:44, "gebowes@... [spectrumanalyzer]" wrote:



 









Hi Garry,To tell you the truth, I had the same reaction when comparing the data sheets. Because each mixer is unique, I would suggest that you just try substituting the M1 J and see what your results are.All it took for me was a few minutes of actual use to sell me on its merits.
  1. Due to the actual better isolation, the LO1 leakage (also know as the zero hump) was reduced in magnitude over 20dB. Possibly more important, the bandwidth of the zero hump narrowed significantly. It now goes into my noise floor (approx -110dBm) at about 1.5 kHz.
  2. A second benefit if reduced conversion loss with an improvement of about 5dB at 1MHz and 18 dBm at 2800MHz compared to the ADE-11X.
  3. The one negative I see is that it is far more important to reverse the R and I ports for high frequencies with the M1J than with the ADE-11X
Here are the results of one set of tests I made:Test signal was the same but filters created different input magnitude depending on frequency. At the same frequency, the input signals were identical for both mixers.I uploaded the test results to the files area (Graham's MSA folder) as ti seems that Yahoo lost the reply with the attachments.Sorry if this got duplicated.Graham









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idnihus
Posts: 19
Joined: Sat Apr 28, 2018 3:50 pm

Re: Noise problem with TG at IF2

Post by idnihus » Wed Feb 28, 2018 5:09 am

Thanks Graham, very interesting exercise. Perhaps my M1J will now be useful after all.

bojan.naglic
Posts: 42
Joined: Sat Apr 28, 2018 3:29 pm

Re: Noise problem with TG at IF2

Post by bojan.naglic » Wed Feb 28, 2018 8:59 am

Hi Graham,

Thanks for these pictures. Great work done by comparing those two mixers. The improvement over ADE11X is quite impressive. Both zero hump and conversion loss.

I am using a diplexer at the Mix1 output and I have added an automatic IF2 switch to switch between the three bands: 1/2/3 GHz. I have some pictures on the Folders tab Doc under my call sign.

Now, by seeing this I am considering using M1J for Mix1. And perhaps going back to manual (SMA cables) IF2 switching. However I think over time of frequent usage SMA connectors do lose some quality.

I presume you are having an input to I port and for the high frequencies you would use R instead.

Thanks for that,
73 Bojan S53DZ

gebowes
Posts: 48
Joined: Sat Apr 28, 2018 3:50 pm

Re: Noise problem with TG at IF2

Post by gebowes » Fri Mar 09, 2018 9:43 pm

Hi Bojan,
Sorry for the delay responding... Life managed to get in the way of pleasure.
Yes, I currently have my MSA input going to the I port (both with the ADE-11X and now the M1J. I had decided not to implement a switching method for higher frequencies as my testing showed only limited benefit with the ADE-11X. Unfortunately, with the M1J, I think I will end up reversing the I and R ports for higher frequency bands at some point in the future.
I also use the diplexer at MXR1 output and use a DuCommun RF switch/relay for the IF2 connection. I am not sure I understand why the M1J might cause you to go back to switching cables. I did perform these tests without the duplexer and relay in the circuit to avoid the possibility of introducing comparative errors, but I do have them in place for normal operation with the M1J.
I spent quite a bit of time at your web site. I must congratulate you. Your documentation is far better than mine and very helpful. Your MSA looks great. I was surprised how similar some of our choices were with regard to the locations of modules and utilization of accessories and/or options. 
One item still on my to do list is the splitter for the 2G tracking generator... i.e. PLO3 direct output for 2G and through MXR3Amp and MXR3 for 1G/3G. I see that you used a splitter and then both sides of a Scotty RFA. Where is your 6dB splitter? Is it inside the RFA? On the same PCB? I haven't done this yet because I did not want two separate pcb's (especially since the splitter probably consists of only three resistors) and have not yet got around to creating a new pcb that incorporates the splitter and combined input.
Graham

bojan.naglic
Posts: 42
Joined: Sat Apr 28, 2018 3:29 pm

Re: Noise problem with TG at IF2

Post by bojan.naglic » Mon Mar 12, 2018 6:55 am

Hi Graham,

I must say I like this Scotty's project a lot. As it can be seen from my pictures I have used some rigid cable remains from the home shelf instead of additional SMA connectors to lower the loses. It proves to work well but it doesn't look so nice. I also added some microwave foam to the bottom of an Alu cover to minimize resonances and reflections as my enclosure is quite big.

Of course there are also things that bother me:
- relatively slow scan (slow for mw filter tuning),
- I used crystal RBW filters with square response instead of triangle for optimal SA use (it is easy business: buy - impedance match - build in - use).
I have just ordered 3 ceramic 300 kHz filters to build another RBW BPF to change an existent 138 kHz filter that I am using now. So it will be like: 300 kHz, 31 kHz, 4.4 kHz, 0.49 kHz.

I am quite happy with my IF2 automatic switch. I have wired it with a three state switch on the front plate to choose between:
a) 1 / 3 GHz
b) 2 GHz
c) auto.
Going back to mechanical switching is not connected with changing the 1st mixer. I am staying on automatic anyway.

Yes, for PLO3 splitter I took a spare RFA-1 board and a lot of shielding. I have assembled both arms the same (two equal ERA amplifiers - 68nH SMD coil, 100pF coupling).
I added a 3-resistor 6 dB splitter to one input,
took a short semi-rigid 50 Ohm cable to get to the second input,
then changed the original input attenuator from 14 to 8 dB to stay on total 14 dB attenuation,
leaving both output attenuators at 2.5 dB.

I will seek for the modified schematics in my documents archive if there are some other changes.

73 Bojan S53DZ

gebowes
Posts: 48
Joined: Sat Apr 28, 2018 3:50 pm

Re: Noise problem with TG at IF2

Post by gebowes » Wed Apr 25, 2018 10:02 pm

Attachments :[/list]Hi Garry,
To tell you the truth, I had the same reaction when comparing the data sheets. Because each mixer is unique, I would suggest that you just try substituting the M1 J and see what your results are.
All it took for me was a few minutes of actual use to sell me on its merits.
  1. Due to the actual better isolation, the LO1 leakage (also know as the zero hump) was reduced in magnitude over 20dB. Possibly more important, the bandwidth of the zero hump narrowed significantly. It now goes into my noise floor (approx -110dBm) at about 1.5 kHz.
  2. A second benefit if reduced conversion loss with an improvement of about 5dB at 1MHz and 18 dBm at 2800MHz compared to the ADE-11X.
  3. The one negative I see is that it is far more important to reverse the R and I ports for high frequencies with the M1J than with the ADE-11X
Here are the results of one set of tests I made:
Test signal was the same but filters created different input magnitude depending on frequency. At the same frequency, the input signals were identical for both mixers.
I deleted the first message because Yahoo scrambled the test results, I have put them in the files area folder "Graham's MSA"Graham

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