I doubt you need a relay.
The two caps that get removed for USB operation (C91 and C92) can remain out for LSB operation as well.
Those caps are there only to allow the old analog VFO on the main Bitx40 to oscillate at 5 mhz.
Removing those caps allows the Si5351 on the Raduino to provide a 19mhz VFO signal to the Bitx40 for USB operation,
works just fine without the caps for the Raduino to supply 5mhz when operating LSB.
Most of us get by without a trimmer cap in the BFO to "clarify" the audio.
I suggest you evaluate the rig first, hack in that trimmer cap if you don't like how the audio sounds.
The trimmer in the BFO should affect receive audio and transmit audio in exactly the same manner.
The trimmer determines the frequency difference between the BFO carrier and the passband of the crystal filter,
which determines the range of audio frequencies that get received or transmitted.
The front end protection diodes are a good idea on currently shipped boards if you will ever
have the Bitx40 hooked up to an antenna while a nearby 100 watt rig is transmitting.
Without the protection diodes, all that would blow is the 2n3904 at Q13, which costs a few pennies.
(Though some might find the soldering job difficult on such a small part.)
.
There have been no changes to what gets shipped from hfsigs (hardware or firmware)
since the Raduino was introduced in Dec 2016.
Jerry, KE7ER
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On Fri, Jul 28, 2017 at 09:54 am, David wrote:
I have received the kit just recently and I understand there are a few modes I can do, for example, adding two caps to the voltage regulator on the rardunio to prevent clicks, and one to improve mic clarity (perhaps a trimmer cap) as well as removing two caps to enable USB operation for digital modes. What I was considering was adding in a small solid state relay close to the board to enable me to easily switch from lsb to usb operation - adding or removing the caps using a dpdt relay. The relay would be controlled by a switch to the ardunio that would then toggle the relay and make the changes to the frequency calculation. Thoughts?
