RF output screwed up.  In all the documents I've never seen a PCB layout or a circuit diagram that contains the LPF (60m) relay circuitry on the main board. The attachments show what I believe is the jumper setup (red lines) from the assembly guide, the 2 green circles are the 2 RF inputs from the synthesizer (RF!) and the 60m LPF (RF0). All the LPFs have been tested using a NanoVNA so they are all good. The RF0 should be coming from the 60m LPF on the main PCB and should be switched out around 5MHz I believe.  Above that the 5 LPFs in the filter kit should be selected according to the frequency setups for the 5 remaining filters and these should be going through RF1 to the selected LPF.. It looks like the RF1 is always going to the filter PCB, while the RF0 should only be there below 5MHz.

On Thu, Mar 30, 2023 at 08:27 AM, Syd wrote:

RF output screwed up.  In all the documents I've never seen a PCB layout or a circuit diagram that contains the LPF (60m) relay circuitry on the main board. The attachments show what I believe is the jumper setup (red lines) from the assembly guide, the 2 green circles are the 2 RF inputs from the synthesizer (RF!) and the 60m LPF (RF0). All the LPFs have been tested using a NanoVNA so they are all good. The RF0 should be coming from the 60m LPF on the main PCB and should be switched out around 5MHz I believe.  Above that the 5 LPFs in the filter kit should be selected according to the frequency setups for the 5 remaining filters and these should be going through RF1 to the selected LPF.. It looks like the RF1 is always going to the filter PCB, while the RF0 should only be there below 5MHz.

 On Thu, Mar 30, 2023 at 08:27 AM, Syd wrote:

RF output screwed up.  In all the documents I've never seen a PCB layout or a circuit diagram that contains the LPF (60m) relay circuitry on the main board. The attachments show what I believe is the jumper setup (red lines) from the assembly guide, the 2 green circles are the 2 RF inputs from the synthesizer (RF!) and the 60m LPF (RF0). All the LPFs have been tested using a NanoVNA so they are all good. The RF0 should be coming from the 60m LPF on the main PCB and should be switched out around 5MHz I believe.  Above that the 5 LPFs in the filter kit should be selected according to the frequency setups for the 5 remaining filters and these should be going through RF1 to the selected LPF.. It looks like the RF1 is always going to the filter PCB, while the RF0 should only be there below 5MHz.

 On Thu, Mar 30, 2023 at 08:27 AM, Syd wrote:

RF output screwed up.  In all the documents I've never seen a PCB layout or a circuit diagram that contains the LPF (60m) relay circuitry on the main board. The attachments show what I believe is the jumper setup (red lines) from the assembly guide, the 2 green circles are the 2 RF inputs from the synthesizer (RF!) and the 60m LPF (RF0). All the LPFs have been tested using a NanoVNA so they are all good. The RF0 should be coming from the 60m LPF on the main PCB and should be switched out around 5MHz I believe.  Above that the 5 LPFs in the filter kit should be selected according to the frequency setups for the 5 remaining filters and these should be going through RF1 to the selected LPF.. It looks like the RF1 is always going to the filter PCB, while the RF0 should only be there below 5MHz.

 Hi Syd. You are correct. There are large chunks of the SigGen that are gathered from other kits. Unfortunately, the schematic in the manual ... let's say is incomplete.

I think that the info you're after may be in AN006.

This shows RL0 and the required jumper location on the VFO/SigGen main board.

AN006 is located on the QRP-LABS  website. Sorry I don't have the link close at hand.
 
You are correct that LPF0/RL0 will switch out above 5MHz. Also, my understanding is that LPF1 is always engaged. It is for signals above 21MHz and to suppress any harmonics generated when the other filters are engaged. (See the Ultimate LPF kit: Relay-switched LPF kit page 2.)

I'm not sure if this answers your specific problem. Good luck.
 
73, Rick
VE7TK

Website: https://www.ve7tk.epizy.com/

I have the filter kit to go with the U3S, but also have the VFO/Synth kit.  The highest frequency filter has to go at a certain position, since it is always in circuit.  I forget which position.  You have to sift through a lot of documentation to get all the information on this thing, but it's all there, somewhere.  A word of warning on the VFO/Synth: there is no coupling capacitor in the output of the VFO/synthesizer, so if you connect it to something that has a transformer input, a choke to ground, or other DC short input, you'll blow the synth chip.  I blew mine the first time I used it.  After letting it sit a few years, I finally got around to replacing the synth chip, and I put a capacitor in series with the output so I won't blow another synth chip.  You might as well do that now before you blow yours up.  Upon attempting to reassemble the thing, I discovered that the BNC connector can't be tightened down in the box because you can't get a wrench on both the connector and on the nut at the same time.  The case should have had a D shaped cutout for the connector and an appropriate connector to match.  I haven't decided what I'm going to do about that.  I'll have to see what's in the junk box or order something from Mouser I suppose.  If you have the same case and connector for the VFO/synth that I have, you might want to go ahead and solve that problem now before you button it up in the box.  I have yet to actually use my VFO/sig gen kit.

   It was just a toy project to fool around with since I already have an HP signal generator. I did install a 5VDC regulator into this thing since it was too easy to put in the wrong voltage and screw up the synthesizer IC, which I did, now anything up to 25VDC is OK to run it.  Looking at all my LPF with my NanoVNA I found no 40M, but a 17M LPF instead!  I unsoldered everything and ordered new caps and hope to have it running in the near future.  The series cap is a nice idea.
73 wt1v