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Now connect the Rooster to an antenna (should be suitable for the band in use). If nothing else you
will hear band noise.
Adjust the RIT to about the 2 O'clock position and call CQ, if called back adjust the RIT for best
reception and enjoy the QSO. Note the RIT control does not change the TX frequency just the receive
frequency so you may find once set you don't need to change it.
Notes
All direct conversion type receivers can suffer from noise and other issues when used with a mains
power supply. We recommend that the Rooster is powered by a battery pack. We have used and
would recommend a 3-cell lithium-ion battery pack that gives just over 11v. The Rooster still
produces around 1.5 watts at this voltage and will operate for a very long time with such a power
pack. A 7Amp/Hr 12v lead acid battery is also a good choice. It is always a good idea to put a fuse in
the power lead. A rating between 1 and 2 amps should be fine. (30m will be a little less)
Other 40m/30m band frequencies can be used by changing the Crystals, if you are only moving by a
couple of KHz then you will be ok just changing the mixer crystal (Y1). If more then you will need to
change all three crystals to the same frequency. (The mixer crystal should have a load capacitance of
about 18-20pf if you decide to try your own crystals)
Something to be aware of with ALL direct conversion (DC) receivers will receiver on both sidebands
at the same time, more or less equally well, that means that you may hear a station that sounds nice
and strong but they do not answer your call, in this case they are most likely operation on a higher
frequency than you but their second sideband is on the Roosters frequency. The Rooster uses a twin
crystal filter in the front end that does help reduce this problem but it's a 'feature' of all DC
receivers.
Audio Filter Response
The Rooster unlike many such simple transceivers, uses an active audio filter. This makes use of the
spare op-amp in the dual op-amp used in the
audio amplifier. This is centred around 700Hz and
has a bandwidth of 500Hz.
The filter is certainly NOT a brickwall but does give
a useful peak of about 12db to its centre
frequency. Here is a waterfall showing the filters
response. We used a Kanga RF Noise source
module for the input to the transceiver and used a
waterfall display to see the response.
Rooster CW Transceiver Rev6
Page 25 of 33
12/02/2024
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