Warren,?
That is great that you tested the coils you removed from the uBITX on a perf board. Were the capacitors also the ones off the uBITX board ? If not, could you add those to your test (I know that asking is a lot easier than doing). You would like to completely duplicate what is on the uBITX board.
As far as it being a layout problem, contact resistance, added wiring capacitance and the actual parts used would be the determining factors.?
This is what I posted on the other thread:
I just looked at the uBITX schematic for 2017 (I believe it to be level V3) and looked how the band switching of 4 LPFs is done with 3 Relays KT1 - KT3. I'm told V4 is the same.
The 3 relay control signals are TXA (KT1), TXB (KT2), and TXC (KT3) which come from the Raduino board.??
The 4 stages of TXA/TXB/TXC are (0 indicates relay not "picked", 1 indicates relay "picked")?:?
0,0,0 which selects the High Band LPF and uses 3 series?relay contacts,?
1,0,0? which selects the Hi Midband LPF and uses 5 series relay contacts.
1,1,0? which selects the Lo Midband LPF and uses 7 series relay contacts
1,1,1 which selects the Low Band LPF and uses 7 series relay contacts.
That's a lot of series (resistive) relay contacts and associated (capacitive) wiring. Adding one more relay,? and associated driver, could cut that down to a max of 2 series relay contacts for each band (one on Input and 1 on Output) and "bus" type LPF wiring (results in less overall wiring).?
73 Kees K5BCQ
