Good evening,

Not wanting to digress from the current design, I have stumbled across this:



It is somewhat similar to the tinySA but uses LM61E2 as the LO. Seems to be a better choice for an LO than the Si4432. Perhaps will try and see if I can give it a go.

Just sharing my thoughts...

73 Elia, M0ZHN

On Mon, Jul 20, 2020 at 02:31 PM, M0ZHN wrote:

Seems to be a better choice for an LO than the Si4432

Seems to be a much better choice for the screen size too!!!
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John P.
WA2FZW

Glenn, I think you meant the Si4432; the 4302 is the attenuator.?

The code is on the page Elia provided the link to, so figuring out how to program the other LO should not be an issue.?
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John P.
WA2FZW

开云体育

Don't know about that! I'm the software guy!? LOL!?
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John P.
WA2FZW

The LMK61E2 is available from Mouser??and Farnell ?on?their UK sites. Not cheap but affordable, I have one in my parts stock-pile, must have bought it some time ago but don't remember what for... It is quite small indeed.

Thanks Elia, Farnell here can get them. But $33 in our $'s

Nice find.? Parts of the code looks very familiar!? Wonder which came first.? Looking at the date I would guess the Visionary was first.

It would be interesting to see if the different oscillator makes any significant improvement to performance, especially given the fairly wide minimum RBW.? For me the main improvement would have to be obtaining a narrower min RBW while keeping the low cost.? 2.6kHz is really too wide for some uses.? The SI4438 spec sheet states 1.1kHz min bandwidth and could be good for the receiver, seems to be available in a module at low cost.? Reduced frequency range so no good for the LO, quite different code to drive it - John?

Thinking aloud here - if we had two SI4432 in RX but offset in receive frequency so only a small portion of the bandpass overlapped, then it may be possible to obtain a narrower resolution but probably reduced dynamic range.? Really depends on how sharp the FIR filters are in the SI4432, and that needs measuring.? I think it can be measured by fixing the RX SI4432 frequency and then sweeping a signal from a signal generator across and recording the results.? Could be a paper/pen exercise (OK - Excel these days) or automated, which i plant to do at some time.

Dave

On Tue, Jul 21, 2020 at 04:32 AM, MVS Sarma wrote:

Costly, ut manageable at 1 off.if you can tolerate delay

I get a virus alert on that link!
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John P.
WA2FZW

On Tue, Jul 21, 2020 at 04:24 AM, m0wid wrote:

Nice find.? Parts of the code looks very familiar!? Wonder which came first.? Looking at the date I would guess the Visionary was first.

My thoughts exactly!!!

quite different code to drive it - John?

Not even going to contemplate it!

Thinking aloud here - if we had two SI4432 in RX but offset in receive frequency so only a small portion of the bandpass overlapped, then it may be possible to obtain a narrower resolution

Not even going to contemplate that either!!!

As I mentioned to Glenn in an email earlier, I'm perfectly happy having a basic fairly accurate SA. If I was getting paid for the time I've spent on this so far, I could have purchased a nice Rigol like Glenn has!!!

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John P.
WA2FZW

The LMK61E2 data sheet shows it to be very similar to the Si549, including the internals and foot print.

73, N7ISH

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