Topics

CS-40F: Radio for FT-8

Adam Rong
 

Gang,

We are working on a radio kit around 7074kHz USB dedicated for FT-8. Basically it is a crystal controlled KN-Q7A working in USB mode with narrow fine tuning range and high frequency stability. The price will be around 85 USD including shipping. Let me know if you like it.

Thanks,
Adam

Michael DB2GM <db2gm@...>
 

Hello Adam 
this is a great idea, we certainly will like such a small device which we can connect to an Raspberry PI3 and then have a small FT8 station.
vy 73 de Michael DB2GM 

Am 02.03.2018 um 17:22 schrieb Adam Rong rongxh@... [CHINA_QRP] <CHINA_QRP@...>:

Gang,

We are working on a radio kit around 7074kHz USB dedicated for FT-8. Basically it is a crystal controlled KN-Q7A working in USB mode with narrow fine tuning range and high frequency stability. The price will be around 85 USD including shipping. Let me know if you like it. 

Thanks,
Adam


n7rgw
 

I like the idea.  Especially being able to connect it to a Raspberry Pi.


On Friday, March 2, 2018 11:43 AM, "Michael DB2GM db2gm@... [CHINA_QRP]" wrote:


 
Hello Adam 
this is a great idea, we certainly will like such a small device which we can connect to an Raspberry PI3 and then have a small FT8 station.
vy 73 de Michael DB2GM 

Am 02.03.2018 um 17:22 schrieb Adam Rong rongxh@... [CHINA_QRP] <CHINA_QRP@...>:

Gang,

We are working on a radio kit around 7074kHz USB dedicated for FT-8. Basically it is a crystal controlled KN-Q7A working in USB mode with narrow fine tuning range and high frequency stability. The price will be around 85 USD including shipping. Let me know if you like it. 

Thanks,
Adam



AA7US
 

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

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.

Thanks,
Adam

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


Adam Rong
 

All,

I realized that frequency stability and precision is a major concern, so I made a few changes and tests. Now the tuning range is reduced to 7073.7-7074.3 kHz in room temperature at about 16 degree C. It will help easy fine tuning.

I did a test for temperature stability. I use hair dryer to heat the board, and monitor the frequency drift by zero beating a stable signal from the generator. The frequency increased about 130 Hz. It explains why we will need tuning range of a few hundred hertz to tune back. Another concern is the short term stability. To minimize the impact, I reduced power to 5 watt, and 15 sec TX will not generate too much heat. I will measure with high performance frequency counter to make sure.

Thanks,
Adam

在 2018年3月3日,下午8:26,Adam Rong <rongxh@...> 写道:

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.

Thanks,
Adam

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


Jim
 

Will the finished version FT8 radio have build in VOX circuit & USB port? Those two things would really help this rig sell.

I think it should have 3.5mm audio in/out ports also.

Will it have a small frequency display for fine tuning?

Adam Rong
 

Jim,

I ran my test based on a USB to TTL converter board. At this moment, I don’t have plan to offer a VOX circuit as the converter will do PTT control quite well.

Thanks,
Adam

在 2018年7月12日,下午11:30,Jim <KH2SR@...> 写道:

Will the finished version FT8 radio have build in VOX circuit & USB port? Those two things would really help this rig sell.

I think it should have 3.5mm audio in/out ports also.

Will it have a small frequency display for fine tuning?