|
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 
|
Use a second 4432 for the tracking generator osc¡ ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? Moderator ¨C North American QRO Group at Groups.IO. ? email:? bill@... ? ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of M0ZHN via groups.io
Sent: Thursday, July 16, 2020 3:24 PM
To: [email protected]
Subject: [HBTE] Tracking Generator for tinySA ?
Good evening all,
I have been thinking about a nice Tracking Generator to go with the tinySA, below is a block diagram of my thoughts. What do you think? Does this look promising and feasible? Is it worth prototyping?
Would love to hear your thoughts.
73 Elia, M0ZHN
|
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 -- HBTE Files section:? /g/HBTE/filesErik, PD0EK
|
I like Bill's proposal of a second SI4432 in the tracking generator, probably easier to get a flat response and good isolation than adding an attenuator/amplifier.? Of course then its almost another TinySA. Assuming this will go with your homebrew ESP32 TinySA then there are some options to experiment with:
- Try your proposal and see how well it works.? Perhaps use a passive splitter/combiner (2 off 33R in parallel for each branch should be near enough) and fit a dummy load to the port when not in use. Requires one SI4432, mixer and assign an IO pin to select it.? With a suitable pull up on the tracking generator and pull down on the main board it should be simple to detect if the tracking generator is connected on power up and initialise it to output the correct frequency.? Tracking generator will need to be positioned close to the TinySA to keep the SPI bus short.? This is easy to do.? Another option would be to use an Arduino Nano, ESP32 or similar that just sets the SI4432 frequency on power up.? This is also easy to do but slightly more work.? Gives more flexibility in locating the tracking generator somewhere convenient on the bench.
- As above with attenuator/amplifier as Erik suggests
- Add another SI4432 to the tracking generator as Bill suggests.? Needs another IO pin assigning.? The TinySA code will then have to control the tracking generator LO as the sweep progresses.? This is also easy to do.
- Make the tracking generator completely independent with its own ESP32 and power source, synchronised to the main sweep via the ESP32 Wifi.? Allows the tracking generator to be positioned anywhere convenient, but a LOT more work to implement so if anyone needs that then its DIY.
If you want to try any of the easy ones let me know and I can create a version for you to try out.? Pins 32/33 (reserved for encoder but unlikely to be implemented) or perhaps better 16/17 should be available for use. If it works out OK then would need to add ability to calibrate frequencies of the other SI4432 to the menus. Dave M0WID
|
Hi Dave,
Thank you for the offer of a trial firmware. I would like try the first option of using an additional SI4432 and ADE25 with the SI4432 CS coming from the ESP32. When this works well will aim to add an attenuator/amplifier as suggested by Erik.
I can put the additional components on a PCB that mounts onto the tinySA sandwich so the SPI lines will be kept short.
By the way, I added shielding to my unit, the overall noise slightly reduced but the spike near 70MHz is still there.
73 Elia,
M0ZHN
|
Erik- an insightful observation, I agree.
|
Here is my lash up tracking generator using two SI4432 into a ADE-25 mixer, the test object is a qrp-labs 20m bandpass filter, the analyser is my homebrew ESP32 version.? Ugly!  Despite no filters on the tracking gen or shielding anywhere it seems to work quite well, almost identical trace to the nano-vna.? The tracking gen IF is offset 600kHz from the main SA IF. The chart below is from the web client.  73 Dave M0WID
|
I knew that would be a winner¡ now for the refinements¡ ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? Moderator ¨C North American QRO Group at Groups.IO. ? email:? bill@... ? ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of m0wid
Sent: Friday, August 14, 2020 3:47 PM
To: [email protected]
Subject: Re: [HBTE] Tracking Generator for tinySA ? Here is my lash up tracking generator using two SI4432 into a ADE-25 mixer, the test object is a qrp-labs 20m bandpass filter, the analyser is my homebrew ESP32 version.? Ugly!
Despite no filters on the tracking gen or shielding anywhere it seems to work quite well, almost identical trace to the nano-vna.? The tracking gen IF is offset 600kHz from the main SA IF.
The chart below is from the web client.
73
Dave M0WID
|
I'm onto V2 of my version of the tinySA board.?? The group of us (M0WID, WA2FZW, G3ZQC & VK3PE) working on this, are using the name "simpleSA" to differentiate from Eriks.
The V2 board has provision for the tracking generator using Daves (M0WID) code as in his post below.? I have ordered some PCB's but even with DHL shipping, its taking a long time for them to arrive. For tracking gen, a 2nd RF board is stacked with the SA RF board and ESP32 controller, forming a sandwich of 3 boards. Plus TFT display.
glenn ,vk3pe>
|
Great news Glenn. I knew holding off on V1 was a good decision :)
Bill VK7MX
On 15/8/20 11:45 am, Glenn wrote:
toggle quoted message
Show quoted text
I'm onto V2 of my version of the tinySA board.?? The group of us
(M0WID, WA2FZW, G3ZQC & VK3PE) working on this, are using the
name "simpleSA" to differentiate from Eriks.
The V2 board has provision for the tracking generator using
Daves (M0WID) code.? I have ordered some PCB's but even
with DHL shipping, its taking a long time for them to arrive. For
tracking gen, a 2nd RF board is stacked with the SA RF board and
ESP32 controller, forming a sandwich of 3 boards. Plus TFT
display.
glenn ,vk3pe>
|
Hi Bill. V1 could still be used with a couple of small mods. V2 is "tidier".
Hope you doing ok down in vk7. We are in lockdown as no doubt u know.?
Glenn?
Sent from my Samsung Galaxy S7 smartphone.
toggle quoted message
Show quoted text
-------- Original message -------- From: William R Maxwell <wrmaxwell@...> Date: 15/8/20 5:46 pm (GMT+10:00) Subject: Re: [HBTE] Tracking Generator for tinySA
Great news Glenn. I knew holding off on V1 was a good decision :)
Bill VK7MX
On 15/8/20 11:45 am, Glenn wrote:
I'm onto V2 of my version of the tinySA board.?? The group of us
(M0WID, WA2FZW, G3ZQC & VK3PE) working on this, are using the
name "simpleSA" to differentiate from Eriks.
The V2 board has provision for the tracking generator using
Daves (M0WID) code.? I have ordered some PCB's but even
with DHL shipping, its taking a long time for them to arrive. For
tracking gen, a 2nd RF board is stacked with the SA RF board and
ESP32 controller, forming a sandwich of 3 boards. Plus TFT
display.
glenn ,vk3pe>
|
Hi Glenn
Yes, I was aware of the small mods to V1 but tidier is something
to aim for, mostly. Not sure what your plans for Gerber release
are but if available later I'll get an order off to China and
distribute the pcbs among the NTARC members back home.
For the moment though, we share some of your lockdown pain, as we
are actually in East Gippsland , on the Lakes and in Level 3.
Can't readily go home for the moment, as we would have to go into
self-funded hotel accommodation, and also put the dogs in kennels,
for two weeks. Would get fairly expensive so we are sitting it out
here on the boat. At least this time around, boating is permitted,
subject to social-distancing etc.
Spent some of the time ordering the modules etc for the spec
analyser. Surprisingly, some orders from China are arriving within
pre-COVID times but others definitely aren't. Ran into trouble
with the? SAW filters though. The Polish seller cancelled the
order on the basis that he couldn't ship to Australia because of
COVID? postage restrictions. Still have to solve that one.
Bill
deOn 15/8/20 6:17 pm, Glenn wrote:
toggle quoted message
Show quoted text
Hi Bill.
V1 could still be used with a couple of small
mods. V2 is "tidier".
Hope you doing ok down in vk7. We are in lockdown
as no doubt u know.?
Glenn?
Sent from my Samsung
Galaxy S7 smartphone.
-------- Original message --------
Date: 15/8/20 5:46 pm (GMT+10:00)
Subject: Re: [HBTE] Tracking Generator for tinySA
Great news Glenn. I knew holding off on V1 was a good decision
:)
Bill VK7MX
On 15/8/20 11:45 am, Glenn wrote:
I'm onto V2 of my version of the tinySA
board.?? The group of us (M0WID, WA2FZW, G3ZQC & VK3PE)
working on this, are using the name "simpleSA" to differentiate
from Eriks.
The V2 board has provision for the tracking generator using
Daves (M0WID) code.? I have ordered some PCB's but
even with DHL shipping, its taking a long time for them to
arrive. For tracking gen, a 2nd RF board is stacked with the SA
RF board and ESP32 controller, forming a sandwich of 3 boards.
Plus TFT display.
glenn ,vk3pe>
|
Hi Bill,
you do not have to stick to the Polish supplier when you have a similar one.
link here: https://www.ebay.ie/itm/5PCS-433-92-MHz-SMD-433MHZ-433-433-92-RF-SAW-Filter-Surface-Mount-QCC8C-SM3838-8/273962954133?hash=item3fc976ed95:g:DUkAAOSwudBdT4~K
I looked at the technical features as the B3555. Compare.
NDF550 link: http://13.124.15.139/pdf/download.php?id=3a61bc5ecdd2a26caa4d25a4aeb11c8e88e357&type=P&term=ndf55073 ps.: eBay item number:? 273962954133
?
-- Gyula HA3HZ
|
Its a pity the NDF550 has a different pin out. Fine if a new pcb was being developed but right now, doesn't suit the pcb with the original part. Seems like the Polish guy is the only one with readily available parts right now. And with Covid19, not easy to get. I also wonder how many more he may have available. Probably started with a reel of them.
I took a close look at my V2 pcb. It would be very difficult to fit these even with track cuts etc.
vk3pe
|
Speaking of SAW filters, Dave has cleverly put a mode in the ESP32 controller version to plot the response of the SAW filters.
It's pretty amazing how it corresponds nicely with the Data Sheet. (Data sheet is for one filter only of course)
|
Hi Gyula.
Many thanks for that pointer. I don't know why I didn't see that
offering earlier, especially since it is relatively local to me.
73
Bill, VK7MX and VK1MX
On 15/8/20 8:22 pm, Gyula Molnar wrote:
toggle quoted message
Show quoted text
[Edited Message Follows]
Hi Bill,
you do not have to stick to the Polish supplier
when you have a similar one.
link here:
I looked at the technical features as the B3555.
Compare.
NDF550 link:
73
ps.: eBay item number:? 273962954133
?
--
Gyula HA3HZ
|
In hindsight, I also realized that the foot layout is different from the B3555.
The Polish seller put it up again as a 50pcs item, so far it has had 2 buyers and more than 10 leftovers. So you can try whoever still needs it.
eBay item number: 264817981759 - enter these 12 numbers into the eBay search engine and provide the link.
73 -- Gyula HA3HZ
|
Mouser also stock B3760, which has the same pin outs as the B3555, slightly wider passband and different matching parts.
I was wondering about using those for the analyser, and the B3767 with centre frequency 447MHz, also stocked by Mouser and also with the same pin out, for the tracking gen, though thinking about it as the B3767 response is narrower it may be better to use the B3767 for the SA and the B3760 for the tracking gen.
Then we could have a two channel analyser if that is of any use.
The problem with Mouser, in the UK at least, is the minimum order for free postage, which is otherwise prohibitive.??
73
Dave
|
It wouldn't be too hard to have another version of my PCB Gerbers to cater for that pinout if required. Glenn vk3pe
In hindsight, I also realized that the foot layout is different from the B3555.
The Polish seller put it up again as a 50pcs item, so far it has had 2 buyers and more than 10 leftovers. So you can try whoever still needs it.
eBay item number: 264817981759 - enter these 12 numbers into the eBay search engine and provide the link.
73 -- Gyula HA3HZ
On Sun, Aug 16, 2020 at 05:51 PM, Gyula Molnar wrote:
In hindsight, I also realized that the foot layout is different from the B3555.
The Polish seller put it up again as a 50pcs item, so far it has had 2 buyers and more than 10 leftovers. So you can try whoever still needs it.
eBay item number: 264817981759 - enter these 12 numbers into the eBay search engine and provide the link.
73
--
Gyula HA3HZ
|
Hi Gyula,
The item number does not come up for me.
Regarding V2 PCB's and the TG, awesome!
73,
Robert, WA2T
|
K9HZ
Gyula Molnar
