1 (tr)uSDX Group Buy

This page will provide you with all the Details and Information of how to Order a (tr)uSDX. From a price perspective this is done ideally in a group buy situation. So get together with your local club, or ask in a forum or newsgroup who else is interested in a group buy. It´s best done locally to keep shipping costs as low as possible, but it´s up to you…

Please look at (tr)uSDX Forum to see if there are group buys going on for your region. If not, please consider providing it, and opening it up for other HAMs.

Because it will be a lot of money for a single person, it might be wise to collect the money up front, so you do not carry all the risk. However, you should be trusted and you should trust the people who order from you. Usually this is no big deal in the Amateur Radio community, as we can trust on the high standard of „Ham Spirit“. We HAM´s are a brotherhood, and usually there´s no black sheep.

Ordering PCB´s with as much as possible pre-assembled

The Process of ordering a pre-assembled PCBs is very simple. Basically, you just need to upload the provided Files. I´ve put enourmous amount of work into the files, so the JLC-PCB System will assign the right parts automatically. So you don´t need to select them manually.

The Normal condition should be: ALL SMT Compomnents should be placed by factory.

However: With current market situation, there will be parts out of stock from time to time. Not knowing which ones that will be, I can only give you common advise, how to deal with that: Either search for alternatives to be placed by JLC PCB (in case of Resistors, Capacitors this is pretty easy and almost everytime successful.) or source them separately and solder them by hand later. In case of IC´s for example, it´s harder. Let´s say the 74ACT00 is out of stock, you need to source them elsewhere and hand solder it later. The OpAmp should not be replaced because you sacrifice performance, if you´re not using LT6231. LT6231 is pretty much the optimal OpAmp for this Job. WIth other OpAmps we have seen lower RX Sensitivity and even bad sideband suppression.

UPDATED Mainboard files Rev 1.2:

OLDER Mainboard files for PCB Order

RF Board Files for PCB Order

The following Block will show you, how the JLC-PCB Order WITH SMT Assembly is done (Step by Step) as an example:

Browse to https://jlcpcb.com/

Click on „order now“ and on the next page click „Upload Gerber“

Upload the Gerber Zip-File of the Board you want to order

After analyzing it should look like this (with Mainboard as example here):

In the next step, chose the amount of PCB´s you want to order. The higher the amount, the cheaper, the single PCB´s will be. However, the maximum amount of PCB´s that will be SMT assembled is limited to 50, so you should do your group buy in amounts / batches of 50 for getting the best Price.

Then you need to assign the correct Layer Sequence. Select the right layers from the dropdown menu.

For Mainboard, this is the right Layer Sequence:

For the RF Board, it´s this sequence:

On the very Bottom of the Page, activate the Silde-Switch „SMT-Assembly“ and click on „Assemble Bottom side“, then click on confirm.

In the next step, it will ask you, to provide the BOM File and CPL File

After uploading those files (matching the Gerbers you´ve uploaded before), it should look like this:

Now, the fun starts…. It will recognize and assign most of the parts, but there might be some stock shortages:

Depending on their inventory, this will vary over time, and decisions need to be made.

Si5351 will most likely be out of stock. Substitute it with MS5351 with almost no disadvantages.

LT6231 will most likely not be available at JLC-PCB. Either try to source it elsewhere and hand-solder it later

In the above example, it says „inventory shortage“ for the 74ACT00. There is no decent substitue, so we have no other choice exept for accepting that.

(Your experience may differ, it´s dependend on daily stock, you need to decide how to proceed)

When you click on „Next“, you´ll get a placement preview:

Even if not everything looks 100% right, JLC PCB will review it and correct that for you. What´s important for us here: All components are on their assigned spot and nothing is out of the PCB.

On this page, you can also see and download a list of the selected items and the unselected items.

You should at least download the list of unselected parts, so you know what parts are left to be source externally.

On the Right side you´ll see the Price Details. For 50 completely SMT placed Mainboard PCB´s (Exept 74ACT00) we will be charged 691,01€

Click on Save to cart.

Then start all over again / repeat the process for the RF BOARD.

In the End, if we start the checkout process, there will be fees added for Customs, Taxes and Shipping.

And final amount in my case is 1240,76€ (including Shipping, Import Taxes and Custom Duties)

This is total cost of 24,82€ per pre-assembled PCB Kit now.

The Goal for the Kit is 50€ , so this still leaves us plenty of room for the Rest of the parts, if we buy in Bulk, considering that 99% of the SMT parts are already on there.

If you open one of the BOM Files, you´ve downloaded above, you´ll see a column named „LCSC“. This column is used for the JLC-PCB System to assign the right parts from their Partner LCSC. As only SMT Parts will be placed one ONE SIDE by JLC-PCB there´s still some parts we need to take care of. However, I´ve either provided LCSC Numbers for you, so you can login at LCSC (with your JLC-PCB Login), add the parts to your cart or -if not availabe:

There are links to alternative sources, like mouser, amazon or reichelt. Even if you cannot order from a certain vendor, it gives you the details of the item needed.

can be ordered very cheap at LCSC

can be sourced from mouser

ATTENTION: In case you need to substitute the BS170s from other sources, watch for the correct Pin-Out Configuration:

I bought from Amazon

can be sourced from Reichelt

Alternative / Substitute Semiconductors in recent Chip Crisis:

U3 Si5351A-B-GT MSOP-10 —-> MS5351
U9 LT6231 SO-8 —-> LM833 with reduced performance
U1 74ACT00 SOIC-14 -> no known substitutes. Suggestions ?
U5 CH340G SOIC-16 -> possibly CH340C
U2 L78L05 SOT-89-3 -> Plenty of Suppliers, should not run out
U6 SN74CBT3253 TSSOP-16—->FST3253

RF Board:
U1 INA219AxD SOIC-8 -> no known substitutes. Suggestions ?
U7 TCA9555PWR TSSOP-24 —–>PCA9555 or CAT9555YI-T2
K1-K5 IM43GR —–>G6KU-2P-Y DC5

Important Notes:

You still need abt 3m (10ft) of 0,4mm (26AWG) enamelled copper wire.

Q4 and Q5 on the RF-Board are spare Footprints. They are for future experiments and do not need to be placed or sourced !!!

If you´re lucky and live in the US, Toroids can be bought way cheaper at kitsandparts.com

SMA Jacks can be found cheap on eBay

That´s about it. Now let´s have a look at the costs:

VendorDescriptionPrice for 50 Sets
JLC-PCBPre-Assembled PCB´s1240,76€
LCSCSmall Parts (incl. DHL Shipping)75,97€
mouserICs, Relays, FETs incl. free shipping/ and taxes407,58€
AmazonOLED Displays and rotary encoders195,93€
reicheltToroids 419,19€
Note: Not in that list: Price for Speakers

Total costs 2339,43€

divided by 50

= 46,79€ per Kit

But there´s a lot potential for saving some money: The given Toroid source is expensive and they can be sourced in Bulk cheaper elsewhere. For example buying the same amount of Toroids in the US from kitsandparts.com, would drop the Reichelt Position from 419,19€ to 97 US$. (around 86€)

The OLED´s and Rotary Encoders could be sourced directly from china, you could use alternative (cheaper) relays, you could use different OPAmps. The list is endless, and you will be able to reduce cost further. However: with 46,79€ per Kit I´m already within my goal and I´ve proven it can be sourced for below 50€ and that´s fine for these instructions.

Add another 10€ for housing and we´re good to go

Housing Files for 3D Printing

Can be downloaded here:


Recommended Printing Settings:

  • Material: PETG
  • Layer height: 0,15mm
  • Infill 20%
  • Tap (cut threads) „Lower Wall“ and „Upper Wall“ before putting M3 Screws in.

If you do not have a 3D-Printer, you can try to find someone nearby you, who offers Printing Service, using that link: https://www.prusaprinters.org/world

For those of you, that want to design their own housing: Here´s the CAD File of the (tr)uSDX PCB´s:

Bear in mind, you still have to to follow the CC-BY-SA licence for the housing !

Klick here to get to the Assembly Instructions