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Softrock rxtx inop

 

Hello,

I built a softrock RXTX some years ago. I think it was around 2012. It worked at the time. Never actually made a contact with it - 1W just wasn't enough power.

I rediscovered it while I was poking around in my junk for another project.

First challenge was the power connector - it's a different size than all the other 12V stuff in the shack. I scrounged a 12V socket out of a defunct wifi router and replaced it. Now the softrock has its 12V.

But it doesn't work. I downloaded the drivers and software off fivedash.com, and the gorgeous SDR display is running....but no actual signals.

I remember I had gotten a high-zoot usb audio adapter to use with the softrock, but now I cannot find it. I did locate a couple of generic green "jellybean" usb adapters, and they seem to work as far as hearing hum and scratches off the input cable.

But the displayed spectrum is all noise, and does not change when I unplug the 12V. Also doesn't change when I unplug the antenna.

I don't remember which band I built it for - but figure 40M or 20M would be a good bet. Whups, that's verified - L2 and L3 are
16 turns on a yellow core. So I built it for 40-30-20.

How to get started troubleshooting?

Just for yuks, I scoped the si570 clock chip and saw a 3V p-p signal at 56.428MHz. It does change when tune with the HDSDR program.

I tried feeding a fairly robust signal into the input from a tinySA. When I did this, it behaved like there was a short at the input transformer. Plug the tinySA directly into the scope - big signal. Plug it into the transceiver input, scope across the
input connect - zilch.

I see there's a broadband transformer at the input, followed by a pi-network LPF. I would expect some modification of the input signal, but not zilch.

Yet I seem to remember it working when I built it.

- Jerry KF6VB
 

Jerry:
The 56.482 is close to the "default" start up frequency of the Si570. Check that pins 7 and 8 are soldered well and not shorted to the metal case of the 570. The USB could also not be working as that sets the Si570 frequency. Even without the Si570 frequency changing, you should be able so see an input at 14.107 MHz.
Do you see 14.107 at U5 outputs and the FST3253 pins 14 and 2.

Dave - WB6DHW.

On 6/16/2021 2:38 PM, jerry@... wrote:
Hello,
?? I built a softrock RXTX some years ago.? I think it was around 2012. It worked at the time.? Never actually made a contact with it - 1W just wasn't enough power.
?? I rediscovered it while I was poking around in my junk for another project.
?? First challenge was the power connector - it's a different size than all the other 12V stuff in the shack.? I scrounged a 12V socket out of a defunct wifi router and replaced it.? Now the softrock has its 12V.
?? But it doesn't work.? I downloaded the drivers and software off fivedash.com, and the gorgeous SDR display is running....but no actual signals.
? I remember I had gotten a high-zoot usb audio adapter to use with the softrock, but now I cannot find it.? I did locate a couple of generic green "jellybean" usb adapters, and they seem to work as far as hearing hum and scratches off the input cable.
? But the displayed spectrum is all noise, and does not change when I unplug the 12V.? Also doesn't change when I unplug the antenna.
? I don't remember which band I built it for - but figure 40M or 20M would be a good bet.? Whups, that's verified - L2 and L3 are
16 turns on a yellow core.? So I built it for 40-30-20.
? How to get started troubleshooting?
?? Just for yuks, I scoped the si570 clock chip and saw a 3V p-p signal at 56.428MHz.? It does change when tune with the HDSDR program.
?? I tried feeding a fairly robust signal into the input from a tinySA. When I did this, it behaved like there was a short at the input transformer.? Plug the tinySA directly into the scope - big signal. Plug it into the transceiver input, scope across the
input connect - zilch.
?? I see there's a broadband transformer at the input, followed by a pi-network LPF.? I would expect some modification of the input signal, but not zilch.
?? Yet I seem to remember it working when I built it.
??????????????????? - Jerry KF6VB
 

Jerry:
I didn't notice you said the Si570 did change when tuned with the HDSDR program. That means the USB circuit and the Si570 are OK.

Dave - WB6DHW

On 6/16/2021 2:38 PM, jerry@... wrote:
Hello,
?? I built a softrock RXTX some years ago.? I think it was around 2012. It worked at the time.? Never actually made a contact with it - 1W just wasn't enough power.
?? I rediscovered it while I was poking around in my junk for another project.
?? First challenge was the power connector - it's a different size than all the other 12V stuff in the shack.? I scrounged a 12V socket out of a defunct wifi router and replaced it.? Now the softrock has its 12V.
?? But it doesn't work.? I downloaded the drivers and software off fivedash.com, and the gorgeous SDR display is running....but no actual signals.
? I remember I had gotten a high-zoot usb audio adapter to use with the softrock, but now I cannot find it.? I did locate a couple of generic green "jellybean" usb adapters, and they seem to work as far as hearing hum and scratches off the input cable.
? But the displayed spectrum is all noise, and does not change when I unplug the 12V.? Also doesn't change when I unplug the antenna.
? I don't remember which band I built it for - but figure 40M or 20M would be a good bet.? Whups, that's verified - L2 and L3 are
16 turns on a yellow core.? So I built it for 40-30-20.
? How to get started troubleshooting?
?? Just for yuks, I scoped the si570 clock chip and saw a 3V p-p signal at 56.428MHz.? It does change when tune with the HDSDR program.
?? I tried feeding a fairly robust signal into the input from a tinySA. When I did this, it behaved like there was a short at the input transformer.? Plug the tinySA directly into the scope - big signal. Plug it into the transceiver input, scope across the
input connect - zilch.
?? I see there's a broadband transformer at the input, followed by a pi-network LPF.? I would expect some modification of the input signal, but not zilch.
?? Yet I seem to remember it working when I built it.
??????????????????? - Jerry KF6VB
 

OK - now it works a little. I indulged in a Startech USB audio card - the kind about the size of a pack of cigarettes, bristling with buttons & connectors, and definitely having a stereo line input. I was able to do the calibration of the LO and also the phase and amplitude of the two baseband signals.

Now I can hear my tinySA set at -60dBm. And it receives WWV. Weakly. And I have heard a few CW signals.
No SSB yet...

I figured out how to enable transmit from HDSDR - after many warnings about how I shouldn't do it without a ham
license :).

Haven't succeeded in making any RF though.... Probably something to do with the setup of the sound card.
 

If I remember it correctly, you need 2 audio cards, one for receive and another for transmit. You can use almost anything for transmit, the computer audio card or a USB audio dongle, you don't need stereo there.

Regards,

Ignacio EB4APL

El 19/06/2021 a las 4:36, jerry@... escribió:

OK - now it works a little. I indulged in a Startech USB audio card - the kind about the size of a pack of cigarettes, bristling with buttons & connectors, and definitely having a stereo line input. I was able to do the calibration of the LO and also the phase and amplitude of the two baseband signals.

Now I can hear my tinySA set at -60dBm. And it receives WWV. Weakly. And I have heard a few CW signals.
No SSB yet...

I figured out how to enable transmit from HDSDR - after many warnings about how I shouldn't do it without a ham
license :).

Haven't succeeded in making any RF though.... Probably something to do with the setup of the sound card.

--
El software de antivirus Avast ha analizado este correo electrónico en busca de virus.
 

If I remember it correctly, you need 2 audio cards, one for receive an > another for transmit.
The card connected to the Softrock must be stereo. IQ receive output. IQ transmit input.
I normally use two stereo cards but it strikes me that a mono card could be used for the mic and speaker output.
Which emphasises the importance of a good card connected to the Softrock.

73 Alan G4ZFQ

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