Re: Tracing receive signal for low signal
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Random cutting of traces is not "my" way of trouble finding ..tho at times I've? been tempted ..Amps at Q12 and Q32 would both need to be well terminated as they would be terminated into the crystal filters ..Both (any) crystal filter is highly reactive around the passband frequency and as such need to be well matched/terminated ..Easiest to add amp at antenna end 50 ohm in/out ..use relay or switch to control receive/transmit ..
That being said, I've dead-bugged a version of the Q30/31/32 amp ..replacing Q31 with a PNP (2n3906).. R31=10 k and R34 150 ohms.. collector of Q31 to R35 ,,,gives (at first glance) ~50 db gain ... Have yet to hack the microBitx to really try it tho
Expect it will be noisy and unstable , but ...maybe
Jim
On Saturday, January 12, 2019, 5:55:15 PM PST, Dave Space <davesspacebar@...> wrote:
So given there doesn't seem to be any significant loading there.? So don't think it makes sense to cut the trace to the mixer anymore right to test? Evans board seems to match a lot of the voltage levels on parts so seems like something else is up perhaps. It seems like we do know with enough power things will work... so potentially could just add amplifier stages after Q12 and after Q32 would likely workaround the rather anemic receive???
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