Re: CS-40F: Radio for FT-8

Adam Rong

John and all,

Thanks for the interest. I have completed building the first sample, and I have the following data:

Weight: 390 grams
RX current: 22 mA @ 12 volt
TX power: 5 watt PEP @ 12 volt
Tuning range: 7072.2~7076.2 kHz for FT-8 and JT-65 and etc
Working mode: Upper Sided Band only
Passband: 300~3000 Hz
IF filter: 4-pole
Front Panel:
1. Tuning and AF Gain controls, and a red LED for TX status indication
2. Microphone connector: You will need a sound card interface circuit to connect from the microphone connector of this radio to PC, and VOX circuit is not included in this radio. Of course, if you wish to add them internally, you have enough room to do so.

Although I have removed IF amplifier stage, after some other modifications, the sensitivity is good enough for 40-meter band. The frequency stability is quite good as it is a crystal controlled radio with narrow tuning range (using varactor diode tuning without inductor in series, and there is no inductor in BFO either).

To answer your question about tuning, just like other radio without frequency display, listen before talk is very important. You can use the waterfall diagram of the software to make sure you receive at the right frequency. What I can assure you is that the TX frequency is the same as the RX frequency. No, RIT or XIT feature is not included on this radio.

If someone wish to test the radio, contact me off line and I am okay to ship this sample at 100 USD including air shipping.


在 2018年3月3日,上午5:19,John Landry landrjoh@... [CHINA_QRP] <CHINA_QRP@...> 写道:

Hello Adam,

I'm very much interested in your new FT-8 transceiver, but first I have a question...

Since the FT-8 mode requires setting (and maintaining) a precise operating frequency, unless we used an external frequency counter, how would we tune this transceiver to the exact, correct frequency? 

Thank you and 73,

John L.
QSO with me at:
IRLP node 3871
Echolink node AA7US-L (38712)
D-Star reflector XRF002A
DMR ID: 3153193

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