[hpsdr] Interesting use for Pennywhistle

[John Ackermann N8UR]

Here's a link to a photo of some Pennywhistles in slightly unusual 
service: http://tinyurl.com/ydk29k9

This is the transmitter board that Mike, W8RKO, built to support the 
frequency measuring test that our local gang put on the air last week 
(details at http://www.febo.com/pages/mvus-fmt).

We transmitted on 80M, 40M, and 20M simultaneously for 48 hours, using 
three Pennywhistles as the final stages.  We ran CW at about 20W output 
for that full period, and the PWs stayed nice and cool for the whole run 
(with muffin fans blowing through them, operating in open air in Mike's 
garage).

The signal chain started with a cesium atomic frequency standard driving 
three low-noise PTS frequency synthesizers.  Their outputs went into a 
keying matrix, then an LPF, a 12 dB gain buffer amp, Pennywhistle, 
another LPF, and finally the antennas.  The drive to each PW was about 
+25 dBm (~320 mw) and that gave us 20W output in CW mode.

W8RKO also designed and built the keying matrix that provided CW ID on 
all the signals.  Bruce, ND8I, built an appropriate LPF to follow each 
PW and keep the harmonics down.

The big amp on the upper left of the photo gave us 50W on 2M, generated 
through the same type of signal chain.

73,
John