Hi Jim,
Yes, you¡¯d definitely want to bypass it on RX.
A single-pole single-throw relay or switch parallel to the attenuator would do it. Probably the relay power would need to be isolated too.
But if you are building a dedicated linear amp for uBitx, you could put the attenuator(s) inside the amp¡¯s RX/TX bypass, and even have one for each band where one is needed, and none where the power is less than the amp¡¯s input. And you could tailor the attenuators on a band-by-band basis to get as close to the amp¡¯s best input power as needed, if the amp has a band selector.
This is probably what I would do if I build a linear to go with it¡ªbut first I want it running and tested for field day. To that purpose, we pray that people are busy winding toroids and loading DHL trucks eleven and a half time zones from here.
I thought about adding a mic gain to control power, which would be easy, but would not affect CW. I suppose you could also put a pot in series to control the power to the pre-driver, but if you forgot and left it turned down, you¡¯d lose power if you changed to a band where the PA doesn¡¯t put out more power than the linear needs (mic gain has this problem, too).
Cheers de W1BWA
