Affordable QRP kits at exceptional value
By Dan Tayloe, N7VE
Surface Mount Board
Through Hole Board
Hendricks QRP Kits is now offering the FireFly, which is a 30 Meter Transceiver Kit with an SDR Receiver and a conventional VXO Tuned Transmitter. The kit was designed by Dan Tayloe, N7VE, and here is his description of the transceiver. The cost of the through hole version is $75.00. Details are below.
The Firefly SDR is a SDR receiver combined with a 2.5W VXO transmitter. This combination has been optimized for cw only operation. The FF SDR includes a built in keyer and includes a 1W audio output for driving a separate cw side tone monitor speaker and a high performance, solid state T/R switch for full break in QSK operation.
The first version of the FF SDR is a 30m version. The final 30m FF SDR prototype has 2.6W output power and has a receiver sensitivity of -128 dbm as measured in a 500 Hz receiver bandwidth using a Presonus Firebox "sound card". The receiver is centered on 10.114 MHz and is capable of tuning +/- 24 KHz from that point. The VXO transmitter uses a two crystal "super VXO" configuration and nominally covers 10.102 to 10.113 MHz, although the actual tuning range will depend on the exact characteristics of the particular crystals you get.
An SDR receiver has low level stereo audio outputs and is designed to feed into the audio sound card of a computer. Best receiver results will be obtain using a good sound card such as a Delta 44, which incorporates a high end 24 bit analog to digital (A/D) converter. However, even the 16 bit A/D converters of a typical PC sound card should provide usable received signals although at a reduced sensitivity.
It is very amazing to be able to watch activity across a +/- 24 KHz segment of the band and know without tuning where the signals are and how strong they are. You can even watch DX pileups in progress. With the Firefly SDR, you can tune the transmitter exactly were you want it (visually!) using the spot function, then jump in and go for it.
The FF SDR controls consist of a tuning knob for the VXO controlled TX, a TX spot switch, a cw speed control for the built in keyer, a programming push button for the keyer, a sidetone monitor speaker output, a keyer paddle input, a I/Q stereo output which is connected to the computer sound card, and an antenna jack. The basic kit does not include a case, nor external pots, switches, and jacks.
Again, the FF SDR has been optimized for cw only operation. The use of a dedicated internal keyer chip with a 1w audio sidetone speaker output totally eliminates any lag associated with running cw on an SDR transceiver.
This kit is sold out.
Through Hole version - Prototype Board
Firefly SDR TH Improvements:
Most of this changes are fairly minor, but this latest pass allows a few
of these upgrades to get put into place.
Firefly (Surface Mount) Builders Manual (ver 7)
Firefly (Through Hole) Builders Manual (ver 1)
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