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Relay Board version 5 and BPF switching #bpf

Colin Buckup
 

Hello gang,

Continuing my quest to complete the multi-band 5W Tx/Rx project, I just got my latest batch of kits in the mail. Included was the Relay Board revision 5 which now has as "normal" the option of always having 1 LPF in the circuit. That works great for the TX side (LPF's). But not so for the RX side since you can't serialize BPF's...

Canvassing the web site and the previous discussions it seems that the Assembly Instructions for Revision 5, although making reference to the jumper configuration when using the relay board for BPF switching, never show the correct jumper setting for it and leave it open as  "published in another document".
I could not find this document anywhere on the site... did I miss anything?

Looking at the circuit diagram it seems that if I want to use the 5 relays to switch 5 different BPF's, the output side of position 1 is ALWAYS connected to the center pin of the SMA coax connector. That would mean that if I configure the jumpers as NOT always having pos 1 in series and would as an example select any other position (say relay 4) and since the relay in position 1 is not energized (grounding the output of the BPF) that this would pull the SMA center pin to ground.

Do I need to perform a slight surgery on the board to prevent that? Anyone with previous experience in this? Rev 4 was easier since the RFin and RFout lines were always clear of the non-energized relays.

Hans, any ideas? does that jumper config doc exists somewhere and did I miss it?

Thanks to all

73
Colin - N5GG

Hans Summers
 

Hi Colin

Please see http://qrp-labs.com/ultimatelpf.html , I have just added this information to the page. 

73 Hans G0UPL

On Fri, Jan 19, 2018 at 3:38 AM, Colin Buckup via Groups.Io <rotbaron77@...> wrote:
Hello gang,

Continuing my quest to complete the multi-band 5W Tx/Rx project, I just got my latest batch of kits in the mail. Included was the Relay Board revision 5 which now has as "normal" the option of always having 1 LPF in the circuit. That works great for the TX side (LPF's). But not so for the RX side since you can't serialize BPF's...

Canvassing the web site and the previous discussions it seems that the Assembly Instructions for Revision 5, although making reference to the jumper configuration when using the relay board for BPF switching, never show the correct jumper setting for it and leave it open as  "published in another document".
I could not find this document anywhere on the site... did I miss anything?

Looking at the circuit diagram it seems that if I want to use the 5 relays to switch 5 different BPF's, the output side of position 1 is ALWAYS connected to the center pin of the SMA coax connector. That would mean that if I configure the jumpers as NOT always having pos 1 in series and would as an example select any other position (say relay 4) and since the relay in position 1 is not energized (grounding the output of the BPF) that this would pull the SMA center pin to ground.

Do I need to perform a slight surgery on the board to prevent that? Anyone with previous experience in this? Rev 4 was easier since the RFin and RFout lines were always clear of the non-energized relays.

Hans, any ideas? does that jumper config doc exists somewhere and did I miss it?

Thanks to all

73
Colin - N5GG


Colin Buckup
 

Thank you Hans!
Your web page is very much appreciated. I'm pretty sure others will find it useful.

One suggestion for an eventual rev6 for the relay board:
Provide another set of jumpers so one can select at the lower right corner of the board where to connect the SMA center pins, either to the Position 1 output (for LPF's) or to the RFout rail (for BPF's). That would avoid having to perform surgery to use the SMA connectors in case of using BPF's. I believe there is enough space without having to redraw too much of the PCB.
73
Colin - N5GG