[hfsig] 20m WSPR shield for Raspberry Pi

Bryan Corkran bcorky at gmail.com
Fri Mar 22 17:22:15 EDT 2019

I had a lot of trouble with power, in the end I bought the “official” 2.5 amp adapter and had no trouble after that.
Keith is right the shield is designed for the V1 board hence the little slot in the middle for the display port. I had problems with the shield fouling on the heat sink I’d added on a 3b board so I used a GPIO extender to raise it a small amount.

Bryan, VK3KEZ

> On 23 Mar 2019, at 5:36 am, Keith Wilson <keith.wilson.pcs at gmail.com> wrote:
> I have the 20m WSPR shield working on a new Raspberry Pi 3 B+.  I see apparent mixing products in the output, 120 Hz away from fundamental, when using a USB power bank to power the Pi.  Since these are not coming from a switching power supply, where are they coming from?  These products start at about 30 dB below the fundamental.
> Also, with a scope I measure the voltage output at 12V peak to peak into quality 50 ohm dummy load.  This is 0.36W, higher than the 20dBm (0.10W) specified.  Is this too good to be true?
> Note the shield was not designed for the Raspberry Pi 3 B+ so it can't be fully inserted on the 40 pin GPIO plug, but seems stable enough partially inserted.  Getting WSPR reports from across the USA and occasional overseas reports too.
> Keith - KE4TH
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