Band switching for Portsdown4/ Langstone

[g4saq]

Having completed my basic Portsdown 4/ Langstone, I'm moving on to build the Tx and Rx chains for different bands. The Tx side has been made very easy by the BATC 8 band decoder and switch PCBs. I will be interested to hear what others are using for switching the Rx paths, please. Perhaps multi-way SMA relays?? (not cheap!) Ideas greatfully received. Thanks, Russ.

[G4KLB]

Hi Russ, you may like to have a look at this https://wiki.batc.org.uk/The_MacGuffin_Project

Not got around to tidying up the info as haven't been able to arrange the Wiki layout as I wanted it but all the info is there.
Colin

[g4saq]

Thank you, Colin, that's really interesting. I would not have found it on my own! I'm interested in why you have not chosen to incorporate the BATC 8 band decoder/switch for the Tx chain? I have just bought all the parts and now realise that the price may be a deterrent! It seems pretty neat though.
Regards,
Russ

[M0YDH]

Hello Russell
If you can find a many into 1 coax switch at a rally or on the web for sale then I used one of these to make my three band Rx/Tx changeover controller.
This one uses logic chips and G3KKD's sequenced changeover design to take the 4 band decoder outputs minus 70MHz [wasn't much use at the time] to connect the right amp or the receiver to the one aerial. I have a 4into 1 non-latching switch. It's been brilliant as I don't mind coupling one of the three aerial coax leads lying around the tailgate of the car into the rack.

The other schematic is for the device under development by M0RNW for the G8TA unit seen in CQ-TV 278. We have a latching 6 into 1 coax switch so need pulsed switching . Ron likes Arduino sketches and the resulting circuit card will fit easily in the unit rails.

73 Merry Christmas
David M0YDH

[g4saq]

David, Very many thanks for this. I believe I have seen your excellent handiwork at events (prob CAT22). I am hopeful of acquiring a 6 way relay shortly so fingers crossed. I will study your docs tomorrow whilst dinner is cooking!
Have a good one.
Russ

[g4saq]

Heads up - Agilent 6 way SMA relay on Ebay at an affordable price. I bought one last week and it works fine. Mine is a T24 option which has TTL level switching although it still requires 24V supply. It latches and the switching current is interrupted once latched. The data sheet is online.
https://www.ebay.co.uk/itm/295473392017 I have no connection with the seller, who was vcery helpful.
Russ.

[g0mjw]

Check the power rating, excellent for instruments and switching low power signals. Very low loss, excellent isolation. These are often limited to 1W RF switching.

See https://www.keysight.com/gb/en/assets/7 ... 9-6032.pdf

They are £1572 new.

Mike