Re: discrepancy in the build instructions for receiver kit.


Hans Summers
 

Hi Geoff

Yes it is confusing, I agree. This is quite an old kit and my skills have improved, hopefully  ;-)

The schematic is labelled in a sensible way, i.e. filter IN is shown connected to the RF input, and filter OUT is shown connected to the trifilar transformer T3 (and I have no idea, why there are no T1, T2, as you observed - but that is not an important thing). 

I cannot change the IN and OUT labels on the BPF silkscreen because this would create enormous confusion, since there are already 7,558 BPF kits out there. 

Note that the BPF is symmetric so it makes no real difference which direction the signal flows through. 

The PCB layout is slightly wrong, this is the real problem. The correct solution to this is to re-route two traces and not change anything else. That way the whole thing becomes correct. The circuit diagram, IN/OUT locations, etc. 

So I have just made a change to my local PCB copy, so that in future it will be like the attached diagram. But this will have to wait for the next manufacturing run, which is some way away, since I have just started using a new batch of 250. 

ANYWAY as you said, this does not affect in any way the function or performance of the module. It's a technicality which as you said, could cause confusion during fault finding, and should be fixed. But not of critical importance. 

73 Hans G0UPL
http://qrp-labs.com





On Wed, Aug 12, 2020 at 12:40 AM geoff M0ORE via groups.io <m0ore=tiscali.co.uk@groups.io> wrote:
The assembly of my U3S kit + receiver is progressing well. U3S is completed and working OK.
Assembly of the receiver board nearly done and ready for intregation with the U3S. After building the BPF board and inserting into the mother board, I checked the connections to their destinations.
Using the schematic on page 2 of the instructions (rev 2), I could not get continuity from pins 3 & 4 of the OUT socket to the primary of T3. ( what happened to T1 & T2?)
I then could not get continuity from pins 1 & 2 of the IN socket to the source of Q1.
Looking at the PCB layout on page 5, the blue traces show that the pins of socket adjacent to IC2 go to the transformer winding and alternative RF input. Other blue traces show the pins on the socket adjacent to R21 / C16 go to the source of Q1. Buzzing out the connections on the board confirm these findings.
In conclusion, the IN and OUT labels on the schematic should be reversed and the screen printing on the BPF board needs to be changed and the diagram on page 17 also needs to be amended.
Given the number of these kits which apparently have been built, I am surprised that this anomaly has not been spotted before. It does not prevent operation of the kit but could hamper any faulting. Sorry if these findings cause any distress. I am very satisfied with the kits and the very high standard of the documention.

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