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Author Topic: FlexRadio on CW?  (Read 3345 times)
K8AC
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Posts: 1477




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« on: February 02, 2006, 06:54:21 AM »

Anyone using the FlexRadio SDR-1000 on CW?  I understand that at one point there were some timing problems due to latency in the DSP code that affected rapid turn-around from xmit to receive (or vice versa).  I'm not talking about using it for full-break-in, just DXing where it's important to be able to tell who the station came back to.  
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KD8K
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Posts: 14




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« Reply #1 on: February 18, 2006, 07:02:56 PM »

I regularly use the FlexRadio for CW. With the proper settings, the latency while sending is minimal. I have no problem using the built in software keyer at 25wpm or so. However, please keep in mind that there are several things that can greatly affect this. First, a high quality sound card with ASIO drivers is a must. I use the Delta 44 sound card. Also, there are several settings in the PowerSDR program that can affect latency, such as Sound buffer size and DSP buffer size. These settings have to be balanced between performance vs latency for good cw operation.

The T/R switching however is slow, and is not QSK. The SDR-1000 uses a loud and slow relay to switch with, and in my opinion this is the SDR-1000's biggest weakness. In my opinion, if the SDR-1000 used diode switching instead of a relay, something close to QSK would be possible. Right now however semi-break in is only avaiable and for quick CW exchanges I manually key the T/R switch in the PowerSDR console.

Despite all of this, I still like the Flex radio on CW because if its receiver, it is the best CW receiver I have heard, and that includes my K2.

73,

John KD8K
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AB7R
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Posts: 132




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« Reply #2 on: February 22, 2006, 09:21:52 AM »

There are additional things you can do to set it up for even better performance.  I use an external USB CW keyer by Microham.  This way other external programs can talk to the USB keyer.  This keyer  connects to a hamgadgets Universal keying adapter II, which then connects to a native COM serial port on the computer using pins 4 and 8. This works very nicely and  you can adjust the semi-breakin delay from the SDR keyer screen.

The SDR is excellent for weak signal work as well.  I enjoy doing some QRP foxhunting on Thursdays and even the 5W signals show up on the panadapter display.

73
Greg
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K8AC
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Posts: 1477




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« Reply #3 on: February 22, 2006, 10:37:14 AM »

Is there a jack that allows connection of an external CW key, or must all external keying be done via a USB port?  When using an external keyer, does the SDR-1000 follow keying at a speed of, say, 32 WPM using semi-breakin?  I'm aware of the lack of QSK and have no interest in that.  My question relates to the ability to send CW at high speeds without dropping characters or code elements. Is the turn-around time fast when switching from transmit to receive? In other words, can the delay time be set to a very small value?  
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KD8K
Member

Posts: 14




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« Reply #4 on: February 23, 2006, 10:32:31 AM »

I am not sure on your question on the external USB Keyer but as far as your questions on the Transmit and Receive delay on the SDR-1000, I believe that the shortest delay that can be set is 150ms, but I have had no success using this delay, as it clips the elements of CW, even with an external Key. I set a rather long delay, preventing reception between elements or words. Perhaps others have had some success at lesser delays, but I have not, and even if it did work, I would find the clicking of the relay to be very distracting.

73,

John, KD8K
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KD8K
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Posts: 14




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« Reply #5 on: February 23, 2006, 03:23:41 PM »

Just to clarify the above, I have no problem at all sending at 30 wpm+, the sidetone follows my keying very well, with no noticable delay, and it transmits fine at this speed, with no clipping as long as the T/R delay is set to a large value. This large value however prevents reception between elements or words. Any smaller setting then this will start clipping of the elements, at least on my setup. Hopefully a hardware change will be made which will turn a already good CW radio into a great CW radio.

73,

John, KD8K

 
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WO7R
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Posts: 792




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« Reply #6 on: July 14, 2006, 04:15:09 PM »

The latest level of software has made the CW experience even better.

In any case, I've used it for over a year and a half now.  Mostly CW and HF.

Among other adventures, I've managed a from-scratch DXCC on 80 meters in a couple of months this past winter with just a trusty HF2V for an antenna.  At least 80 per cent were done with 60 to 100 watts, including places like Southern Australia, which is near antipodes for me.  

I was probably just about the first station in the log during the Vanuatu DXpedition of last winter.  Just tuning around and there it was, right on 80 meters.



Larry  WO0Z
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W9OY
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Posts: 1318


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« Reply #7 on: January 21, 2007, 06:49:33 PM »

The SDR-1000 and latest PowerSDR has a turn around time of about 5ms.  This is equivalent to the rise time of a "dit".  Not the length of a dit but the rise time of a dit.  

I have an Orion and a SDR-1000.  The Orion has become my 75M rag chew radio and the SDR is my every day CW DX-pileup machine.

73  W9OY
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