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Author Topic: CW and Digital Receivers  (Read 2429 times)
N5GZH
Member

Posts: 87




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« on: December 31, 2013, 09:01:03 AM »

I'm back into ham radio and mostly CW after a roughly 12 year lag.  My last rig was a Ten-Tec Argosy with 1.8 Khz and 500 Hz crystal ladder filters.  My current rig is the Kenwood TS-590.

Could be my imagination, but CW signals don't seem to pop up out of the noise as well with the modern rig  as with the old setup.  But also, I am using a noisier antenna and different QTH as well.    And it has been a very long time !  Anybody have thoughts on this ?  I still have the Argosy (in need of a new dial string) and it might be interesting to set up a side by side comparison. 

Thanks,

Jim
N5GZH
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NO2A
Member

Posts: 769




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« Reply #1 on: December 31, 2013, 01:41:16 PM »

The modern rigs hear much better with better sensitivity and dsp. The drawback is you get more phase noise,and high pitched hiss,that can be a real pita! Even so,with a high qrn level on noisy 80m,I had a nice daytime cw qso.
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WB0FDJ
Member

Posts: 141




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« Reply #2 on: December 31, 2013, 06:04:19 PM »

I am sure that there are good engineering terms for describing this, but I'm inclined to agree with you.

Like so many hams who grew up listening to the bands through simpler superhet receivers, I must have developed a "taste" for what a radio should sound like and how it ought to handle signals against the usual backround noise. I have a couple of decent, newer, DSP based rigs that do a lot of things very well. But when I head to the shack, I turn on an old TT Argonaut 509. Two reasons: (A) its simple, I don't have to turn on a computer, all the controls are right there in front of me (B) I like the "sound" of the receiver copying CW. Signals do seem to "pop out" against the back round.  The CW note seems to have a kind of simple clarity that is missing in my other rigs.

73 HNY Doc WB0FDJ
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ZENKI
Member

Posts: 924




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« Reply #3 on: December 31, 2013, 10:45:12 PM »

Well If you want signals that are weak to pop out of the noise get a good SDR receiver or transceiver that is direct sampling. I have  DC receivers that outperform modern
radios in terms of making weak signals pop out of the noise. My R2 DC receiver is actually better than my K3 and TS590s in dealing with and making weak signals more readable. The only radio that will outperform a good DC receiver is the SDR direct sampling which after all is a modern digital direct conversion receiver.

SDR receivers make the best CW receivers. One of the reasons for this is that the INBAND RX IMD is so low. Many radios like the K3 have high fatiguing levels of RX IMD
The ARRL used to test for RX IMD, they dont anymore. On many radios the AGC's contribute a lot of distortion on the signals so its a combination of a good AGC design and a linear audio chain. Needless to say current model radios with 20% distortion and over driven 1 watt PA's dont help. They can never for example equal a tube radio for crystal clear clarity.

My K3 also appears to so noisy and harsh, despite the DSP upgrades. For this reason its the receiver I use when I relax and enjoy CW I prefer to use a SDR receiver. For weak signal reception, the SDR is unequaled. Despite my SDR receivers having less sensitivity than my main ham radios they can hear very weak CW signals that are virtually undetectable.  I must say radios like the K3 can detect these signals but the readability without using heaphones is very poor. With a SDR receiver you can click on a very weak signal and it will be there crystal clear and sharp like  the best analog CW radio. Signals just pop out in your face and this is how I remember working CW with my old radios. I could work a mishmash of JA's on 15 meters that were on the noise floor of the receiver and copy them like they were 5/5. I cant do this with my K3 without fighting the radio and twisting knobs all day. On the SDR i just click and adjust the filter with and theres the signal loud and clear and not moving the S-meter.

Anyway try a good DDC SDR receiver, I am sure it will mee your expectations.  This is the problem with the current receiver debate. Its all about chasing numbers for contesters who only use their radios for a few time a year. The rest of us who do daily hamming and operation have to live with all the poor design features like fatigue. phase noise, audio hiss etc etc. A good receiver should have a good set of numbers and be a joy to listen too all day. This is not what you always get with  many of the so called best grade high receiver number radios.  For the general ham digital receivers and transmitter will be the best bet in the future. I had a chance to play with the Flex6000 series of radios and  on CW receive they are excellent despite all the problems with this radio. I am no recommending this radio to you but if you get a chance have a listen to a Flex6000 radio on CW its awesome just like its is a Hermes or any other good SDR radio.

I'm back into ham radio and mostly CW after a roughly 12 year lag.  My last rig was a Ten-Tec Argosy with 1.8 Khz and 500 Hz crystal ladder filters.  My current rig is the Kenwood TS-590.

Could be my imagination, but CW signals don't seem to pop up out of the noise as well with the modern rig  as with the old setup.  But also, I am using a noisier antenna and different QTH as well.    And it has been a very long time !  Anybody have thoughts on this ?  I still have the Argosy (in need of a new dial string) and it might be interesting to set up a side by side comparison. 

Thanks,

Jim
N5GZH
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N5GZH
Member

Posts: 87




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« Reply #4 on: January 01, 2014, 04:56:11 AM »

It's reassuring to know others are hearing the similar things.  Maybe I'm not going deaf and senile after all.   Cheesy
 I love my TS-590. But sometimes I feel like it is running me instead of the other way around. 
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KD8IIC
Member

Posts: 156




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« Reply #5 on: January 01, 2014, 05:56:48 AM »

 I find even when using a newer DSP rig, the old advice of "turn down the RF Gain and crank up the volume" still is best practice.I also use the attenuator, not much background noise now, just Morse.
As for BA's, The R390's and 390A's have a limiter that works real well on those old fellas and it helps too.  73
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N4DSP
Member

Posts: 124




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« Reply #6 on: January 02, 2014, 07:44:41 AM »

Zenki,
which SDR would you recommend? And for the person who doesn't know anything about this new technology,  Wink , ME
what are some good starting websites to read about it?



Well If you want signals that are weak to pop out of the noise get a good SDR receiver or transceiver that is direct sampling. I have  DC receivers that outperform modern
radios in terms of making weak signals pop out of the noise. My R2 DC receiver is actually better than my K3 and TS590s in dealing with and making weak signals more readable. The only radio that will outperform a good DC receiver is the SDR direct sampling which after all is a modern digital direct conversion receiver.

SDR receivers make the best CW receivers. One of the reasons for this is that the INBAND RX IMD is so low. Many radios like the K3 have high fatiguing levels of RX IMD
The ARRL used to test for RX IMD, they dont anymore. On many radios the AGC's contribute a lot of distortion on the signals so its a combination of a good AGC design and a linear audio chain. Needless to say current model radios with 20% distortion and over driven 1 watt PA's dont help. They can never for example equal a tube radio for crystal clear clarity.

My K3 also appears to so noisy and harsh, despite the DSP upgrades. For this reason its the receiver I use when I relax and enjoy CW I prefer to use a SDR receiver. For weak signal reception, the SDR is unequaled. Despite my SDR receivers having less sensitivity than my main ham radios they can hear very weak CW signals that are virtually undetectable.  I must say radios like the K3 can detect these signals but the readability without using heaphones is very poor. With a SDR receiver you can click on a very weak signal and it will be there crystal clear and sharp like  the best analog CW radio. Signals just pop out in your face and this is how I remember working CW with my old radios. I could work a mishmash of JA's on 15 meters that were on the noise floor of the receiver and copy them like they were 5/5. I cant do this with my K3 without fighting the radio and twisting knobs all day. On the SDR i just click and adjust the filter with and theres the signal loud and clear and not moving the S-meter.

Anyway try a good DDC SDR receiver, I am sure it will mee your expectations.  This is the problem with the current receiver debate. Its all about chasing numbers for contesters who only use their radios for a few time a year. The rest of us who do daily hamming and operation have to live with all the poor design features like fatigue. phase noise, audio hiss etc etc. A good receiver should have a good set of numbers and be a joy to listen too all day. This is not what you always get with  many of the so called best grade high receiver number radios.  For the general ham digital receivers and transmitter will be the best bet in the future. I had a chance to play with the Flex6000 series of radios and  on CW receive they are excellent despite all the problems with this radio. I am no recommending this radio to you but if you get a chance have a listen to a Flex6000 radio on CW its awesome just like its is a Hermes or any other good SDR radio.

I'm back into ham radio and mostly CW after a roughly 12 year lag.  My last rig was a Ten-Tec Argosy with 1.8 Khz and 500 Hz crystal ladder filters.  My current rig is the Kenwood TS-590.

Could be my imagination, but CW signals don't seem to pop up out of the noise as well with the modern rig  as with the old setup.  But also, I am using a noisier antenna and different QTH as well.    And it has been a very long time !  Anybody have thoughts on this ?  I still have the Argosy (in need of a new dial string) and it might be interesting to set up a side by side comparison. 

Thanks,

Jim
N5GZH
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N5GZH
Member

Posts: 87




Ignore
« Reply #7 on: January 09, 2014, 07:28:15 PM »


Well If you want signals that are weak to pop out of the noise get a good SDR receiver or transceiver that is direct sampling. I have  DC receivers that outperform modern
radios in terms of making weak signals pop out of the noise. My R2 DC receiver is actually better than my K3 and TS590s in dealing with and making weak signals more readable. The only radio that will outperform a good DC receiver is the SDR direct sampling which after all is a modern digital direct conversion receiver.

Interesting you should mention Direct Conversion receivers  for CW.  I have an old HW-8 that's been in  mothballs for years.  But I can still recall a kind of audio magic  when the filters were switched in and barely readable CW would come jumping out of the speaker.  Not the same as a side by side comparison of course.    I would love to try SDR technology, but just don't have the $$ to do so at present.

Jim
N5GZH



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W1JKA
Member

Posts: 1631




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« Reply #8 on: January 10, 2014, 06:51:28 AM »

Another vote in favor of the cheesy sounding DSP rig CW processing. Of course if you have only operated a DSP rig (CW) you wouldn't know any different. No experience with SDR so no comment.
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