ELEKTOR FORUMS

Finally built my SDR from the May 2007 article. Although the 10Mhz clock is working I cannot seem to get any tuning or signals using any software, cannot hear the 5Mhz test signal either. Only doubt I have is that my synth chip is type CY27EE16FZEC - I cannot see if this is different from that specified as all data sheets come back to the CY27EE16ZE ? Maybe the FT232RL is not talking to it ?? Can anyone tell me some voltages / waveforms to expect on the control bus ? I have uploaded the binary file btw.
Any help appreciated.
John

The CY27 appears to be stuck on 103.70748MHz. If I measure at IC1 pin 3 or 11 I get 25.92687MHz. Have checked all connections, the FT232 clock is running ok @ 12MHz and I can see a change of logic on TXD and RXD if I change frequencies in the ElektorSDR screen, but the CY27 stays fixed on the same frequency. Maybe the CY27 is faulty, I got it on Ebay from HK. I installed the FT software first and my PC correctly recognises the device. It also shows as a USB device on COM2.

Sarma,
Thanks for your patience. I have reinstalled the CDM and uploaded the initcal.bin using the ElektorSDR software but the CY still refuses to tune. You mention SDR2 .bin - where can I find this ? I am currently using the .bin downloaded from the Elektor page here. Am I correct that I must load the .bin from the Elektor SDR program, you seem to indicate it should be uploaded using CDM in your last post ?
Millsey

I downloaded both the SDR and SDR2, but still it refuses to tune. I guess maybe one of the chips is faulty. On both downloads there are two .bin files now, init.bin and initcal.bin. In any event I tried both to no help. Guess maybe I have to give it up now.
Millsey

Hi Sarma,
I don't want to give up, but I'm from the days of valves and my knowledge of modern chips is very limited. Your mention of USB does make me wonder, but I have tried this on 3 PC's I have here, at least two are USB2. I am confused about the FT drivers, they mention choosing VCP or D2XX first, but I always end up with the same download CDM20600.exe whatever I choose, so I assume the software works it out ? I have removed the drivers as explained on the FTDI website, and the Rx is always recognised and the drivers are re-installed after I do this and plug it into the USB again.
When I monitor the 10MHz signal with my scanner I can hear a burbling noise if I move the frequency slider or the offset or xtal sliders, so it seems the CY is getting the serial data. I will try your suggestion to listen to SDA and SCL at the weekend when I have some more time. Yes, I know to leave the capacitors out, the 10Mhz is measured at 10.006MHz with my counter so I am happy about this working. Perhaps at worst case I should try to replace the CY27 before I abandon it. Not knowing the reason that is causing the problem is the most irritating fact.
Millsey

Hi Sarma,
I am 5 years your junior then !! I have checked the frequency at the output of the 74AC74 and it remains fixed at 25.92687MHz. I am now becoming convinced that the CY27 is faulty. I connected my Oscilloscope to the SDA and SCL pins, and when I vary the frequency in the Elektor tuning software I see negative going pulses on both pins. So I can conclude the FT232 is working I guess.
I have not bothered connecting the audio yet, until the CY27 frequency can be made to change it is pointless. I will consider ordering another CY from Germany this time.
I have used a 200x electronic microscope and cannot see any problems with connections or shorted pins.
I will keep you updated. Are we the only two people using this forum ??
Regards
Millsey

millseyHi Sarma,
Have changed the CY27 and can actually now get the osc to change frequency, but oddly I seem to be getting a 15MHz test signal instead of 5MHz. At least I can now see some light towards the end of the tunnel. I have had no success in connection it to my PC soundcard yet, but at least I have solved one problem. I'll report further news when I can.
Millsey

Sorry for late reply, Millsey !!
It is nice that you replaced the chip. Perhaps you are measuring harmonic as your frequency counter may be having higher gain. once you reduce the front end amplification of the measuring device, you might read the fundamental 5MHz.

for your ready reference, I am attaching a table of test results across the band , the LO output measured after 74HC 74
now you may select other channel number (in3) and go ahead to tune from aerial, wish you all the best

Congratulations, Millsey !!!

I am getting things fine. Never had much of Noise, unless QRM is bad . especially the DRM signal is like CD quality. I saw some reports that in UK and other places where power line modems are used for remote metering etc, the Noise in unbearable.
But as you said, SOFTROCK works same time silent, the SDR needs to be checked perhaps !!
I too tried Softrock but the pnp/npn based crystal oscillator gave trouble and the board was partially SMD . I kept it on hold.
Incidentally which model you have?

The advantage of Kainka's SDR is that, it could be software tuned across the entire band.

Regrading sensitivity, perhaps the 0, 10, and 20 db gain adjustment helps.
You can even try a better component at the Op amp instead of TL084.

I am presently using an active miniwhip antenna designed by PA0RDT. performance is almost like LW antenna with no much space needed. If you did any mods , you may try to upload a note with a photograph, Millsey.