Lightning Strikes!

We've had an active summer weather-wise.  During one storm, our neighbor's tree was struck by lightning which caused it to split down the middle.  While no other structural damage was done, the resulting EMP did cause a few issues in my house.  Some ports in my network switch failed, my Synology NAS ethernet port failed, and my SSB6.1 kit blew out its receiver (I can still hear loud signals but really faintly).

Fortunately I was able to switch ethernet cabling to unused working ports so I still have Internet access (phew!) and my replacement Synology unit accepted my disks without problems so my network backup is online again.  Thumbs up to Synology -- it recognized that the disks came from another unit and it just worked without fuss.

I decided to get another SSB6.1 kit and start again.  I made a few mistakes with my first build (as described in my other posts) and with the RX amps blown, it seemed like a good time for a clean build.

I just received the kit in the mail and noticed that the board revision is labeled as 'rev: 20170511' which is pretty recent!  The board looks the same so I'm not sure what the updates are.  One difference with this kit is that all the ICs are surface mount whereas my old one had through-hole parts for the SA602 mixers and the opto-isolators.  However, the board layout is still designed for through-hole SA602 chips and it includes adapter boards to mount the surface mount chips to the board.  Hopefully the new kit has all the discrete parts included...

With this build, I am going to make the following changes:

• have the voltage regulator off the board
• put the audio amp on another board
• use components for the 17 meter band instead of 80m
• be more careful tuning the coils so the slug does not fall off the threads to the bottom...

My case for the radio is a bit thin (about 3 cm) so I am going to move the regulator off the main board.  Mounting it onto the case will give it a decent heat sink.  The audio amp given with the kit (TDA2003) also runs warm so mounting it on the case may be the way to go.  While that chip is pretty hardy and can take a beating (it is used for car radios), it does run a bit warm for my tastes so I may try substituting another amp (cheap LM386?).  Also, having the audio amp off board will make it easier to insert an audio filter before the amplifier.  This one from SotaBeams looks interesting.