Yes, it will work, but....
Leakage through the mixers of the 433.92MHz signal will kill your dynamic range so it is better to put a 30dB attenuator and a 25dB isolation amplifier between the two mixers
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HBTE Files section:?/g/HBTE/files
Erik, PD0EK

开云体育

Hi Robert,

One question for the group I have been wondering about, is there something which would prevent mounting the attenuator board directly to the TinySA board (no spacers)?? I have not looked into this further but have been wondering.

I thought about that too but the holes do not match between the V1 PCB and the attenuator PCB so I just kept it nut high to avoid any shorts. In hindsight I could have put kapton tape and put it directly but it doesn't matter too much, all I would have gained is about 2mm

73 Elia,
M0ZHN

Looks great Elia!

One question for the group I have been wondering about, is there something which would prevent mounting the attenuator board directly to the TinySA board (no spacers)?? I have not looked into this further but have been wondering.

73,

Robert, WA2T

On Fri, Jul 17, 2020 at 08:58 AM, m0wid wrote:

Maybe a faulty SI4432

That's my guess! It's not like I haven't had a few of those! Might be a drive level issue also; need to do more testing.

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John P.
WA2FZW

Never seen that before.? In principle narrower RBW should give more relaxed timing.? Very strange.

Maybe a faulty SI4432?

Time, and agreement on which pin to use for the additional CS.

Many things to do on the wish list:

• IF_Sweep mode to test the SAW filters
• AM and FM modulation for the signal generator mode
• High frequency range modes for sweep and signal generator
• Zero Span mode
• Web pages for the new modes and settings
• Stored traces on the web chart
• A test mode for the various RBW filters - the response of these really needs to be measured as I am not at all confident they are all flat and nicely shaped.? I plan to make a special version with CAT control of my Hermes Lite 2 in signal generator mode to sweep the filters.? If anyone else can do this and publish the results that would be fantastic.? In fact it would be a good test to slowly sweep a fixed strength signal across the spectrum and see how the response changes with different RBW settings
• Tracking Generator Mode.? Could be either with a second TinySA or additional board

Perhaps need some agreement on the order of implementation, though I reserve the right to work on what interests me most at the time and take as long as I want!

73? back to work :(, M0WID

High frequency modes should be easy to do, as should tracking generator.? Measuring RBW filters is important though.

Well, I ran a test this morning. With a shorting plug on the input SMA connector and running it from a battery pack via the USB port (no PC interference) I saw no spurs anywhere around 70MHz.

But I seem to have another problem; at least at low RBW settings. Look what's happening at ~46MHz, which happens to be where the LO switches from low band to high band. It looks like the LO may stop working sometimes. With a 100MHz range and AUTO RBW, I can see the harmonics from the reference output at 10, 60 and 90, so this is happening intermittently.








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John P.
WA2FZW

Hi Dave,

I am not that good with programming, what is needed to add this option to the software? I am itching to try it ?

Elia

Just a thought, those Si modules use an external 30MHz oscillator. Could that be the cause of the spurs? Will put some shielding this weekend and see how goes

Elia

On Fri, Jul 17, 2020 at 03:28 AM, m0wid wrote:

so wondering if it is some software thing

Highly unlikely.?Elia is running the published (V2.8) code; Glenn and I have?the version I'm working on (2.9) and yours has whatever changes you've been working on I assume.
?
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John P.
WA2FZW

Here is my sweep, attached

I did not get the 71MHz spur until sometime last two weeks, so wondering if it is some software thing, cannot see how.? Change of IF can make it disappear.

I have no shielding either, dummy load fitted to input, reference off.

Tracking generator should work I think, could hook an additional SI4432 to the SPI bus.? Erik's approach for his commercial version is to use a second TinySA in tracking generator mode which seems like a good idea to me.


Dave

Just a thought... If you're looking for spurs generated internally maybe one should put a short on the input.?
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John P.
WA2FZW

Not much here at 70MHz.??? My pcb design has provision for filters over most of the rf sections.?? I also anticipated adding a shield plate between the RF and Control decks if needed.
Neither fitted as yet.

glenn

Good evening all,

I have been thinking about a tracking generator to go with the tinySA so I drew the below block diagram of how I understand TG works. Is this feasible? Is it worth prototyping and testing?

Would love to hear your thoughts.

73 Elia, M0ZHN

Hi Dave,

Interesting, I just did a few scans as you suggested and I can replicate the 70MHz spur (65MHz in my case). Curious what is causing it, further investigation needed.

73 Elia, M0ZHN

Hi Dave,

I had some low profile connectors in my pile, I believe they came from mouser but that was a very long time ago. Will see if I can find what part number they were. Here is a photo if it helps, the socket is the low profile one, the header is standard, I just trim the pins to suit.
Elia

Very nice!??

Glad to see another workbench in similar state to my own!

I will be very interested to see how much difference shielding makes to the results, not bothered with my build yet.? If you do a sweep with RBW set to narrowest (it will take some time) that will reduce the noise floor and show any stray signals better.? In my example I sometimes get a spur at around 70MHz from somewhere at certain IF.? Move the IF and it goes.? Not managed to work out where that is coming from yet (note my layout is my own bad design and is quite different to the PCB you have).

Where did the low profile headers some from?? I could do with some of those.

Dave

Hi All,

I received the last of the parts that I needed and the build is now complete... almost... still want to add some shielding, case, etc....

I used low profile headers and managed to reduce the thickness of the sandwich to about 30mm, I am quite pleased with that :D

Some photos with nothing at the input yet