Re: VK4PP uBitx LPF BANK add-on Board

Timothy Fidler

1. Wired OR diodes used for Relays J1A B  great idea. and I can see you seem to have allowed for relay contacts being opposite sensed. Ie J1A B set is active when Energised and Energised is out of cct.
2 . you have three signals and because of the wired or you have effectively four states without using a decoder. So how is the R5 to be energised. ?? Is it there for case of special software mod plus I2C or ....?

3. You need to define the relay functions.  From a Sota point of view it makes sense that J1AB set is a 20/30m Filter. Ie NO relay energised when working 20m.
then J2 becomes 80 m. then J3 40m  and J4 becomes 15/17 and J5 becomes Ten m after some magic.
4. You have allowed  spike suppression diodes for all relays except first pair. Forgotten or  there is a reason. ? 
5. Kees Talen is also talking of a Five relay board design.  With Decoding to be done Off board somehow. Perhaps you need to check up his thoughts.
6. Given  5.  I would suggest that you allow sufficient pads for a  74HCT42 decoder and  a 78L05 to power it.  These pads could be on basis of wired chip mounted as SM (legs become feet at 2mm up from tips) so the cost of the holes is not there.  You will also need 4 off BS250 P Mosfets  (simplest solution and they are cheap) to activate the last four relays sets.  The points where the Wire goes off to the Wired OR should be  a through hole rondel.  All this could be squeezed in up T LHS of board as presented without much increase in board space.

The final wiring could be done with  Cat E wiring cores stripped out for those who wanted to go this way . I would suggest the following mapping  000 as input to decoder  means nothing.  Same for 001.  010 activates relay set 2 and also energises J1AB via wired OR  .  ...etc all the way to 101. If you use PNP transistors, you will be up for one extra current control resistor per bit.  BS250s are logic level Mosfets  RDS on approx 14R. have  them Rockby in Australia list them but have to order them in. 

The mappings and Relay usage have to be defined up front or  the software will be a schmozzle. 

Is the current voltage going to K1 coil 12V .. the schematic calls it Tx voltage. It appears likely to be 12VDC but without details of the guts of the Raduino I cannot be sure.

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