The SBX-11/SBX-11A can be used from 160m to 40m, so that only gives me 4 bands: 160m, 80m, 60m and 40 m to use on SSB. The original unit had only four channel positions, and I need four bands, so I was thinking of just using the original front switch. The original switch is five (5) wafers. The wafers on the switch have 5 contacts, and are used with one contact being IN, and the other four contacts are the OUT to the various Filters. Most of the wafers have a second set of contacts, to get the output from the filter, and then the one line back to the main circuit board. I wanted to keep away from using the relays (which could be used) to avoid any more power overhead when transmitting. I would be using the transceiver on the original 12 VDC "D" cells. The receive current on the SBX11/SBX-11A is about 30 mA, which is amazingly low. That is what makes this radio perfect for cold weather use.
Relays would be nice IF I was just using the radio at home. The main objective of this modification is to get this portable radio back into the field.
I use a modification on the SBX-11/SBX-11A that was used by the Government of Canada for NCR in the Polar Shelf Project to only use on crystal per channel set (Simplex). That relay is only used
on transmit by the PTT. I documented that modification, and have it on the Yahoo Spilsbury SBX-11/SBX-11A group.
By using the FCC-1/FCC2 DSS VFO, increases the current draw by the DSS VFO, which is more than the entire radio on receive. Digital is nice, but can increase the current overhead.
Lots of combinations that can be used for the QRP-Lab filter board. Sort of a Swiss army knife design. Keep the questions and ideas coming!
73 Stuart VE3SMF/VE8SMF/VA3YO