K2 phase noise
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Thank you for the responses and I'm pleased to get some discussion going on
this subject on the reflector. Phase noise has been brought up before, but not discussed in detail. As I said I've had personal emails about this so I know I'm not on my own here. I should point out that my comments were not intended to 'slag off' the K2, and I am not 'obsessed by numbers'. I don't expect the K2 to have lab grade performance, nor to outperform high price rigs. My sole reason for looking into this (believe me I've got better things to do) is due to complaints about my signal on air. These have been from respected and technically competent amateurs. I can go into detail if required. Several months ago I had some exchanges with Gary and Eric, and sent them some analyser plots. More recently I've done comparisons at 300Hz from carrier using a HP8640B as a reference, and I soon should be in a position to produce more detailed plots of the close in phase noise. Although the comparisons I've made clearly show the K2 is inferior to the MP, 870 and a home brew rig in this respect as stated, the phase noise performance to me seems adequate, however, that doesn't explain the comments I've received on air. I get very similar results with two K2's, one built by me and another by GU3MBS, who is a very experienced K2 builder. Both have all the latest mods. At other times I've received good reports, possibly from less critical operators? I want to get to the bottom of this so that I can confidently use my K2 for QRO contesting. The rig has many fine attributes and I take my hat off to Wayne and Eric for their excellent design and production engineering. By the way I've moved the K2 as far as practical from hum sources (>2') and even tried enclosing it in a mu-metal shield, so I'm pretty confident that magnetic modulation isn't the culprit. 73 Fraser G4BJM _________________________________________________________________ It's fast, it's easy and it's free. Get MSN Messenger today! http://www.msn.co.uk/messenger _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: K2 phase noise
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Morning Fraser,
Your comments understood, and I agree with you about the design / production engineering. There is the possibility that a Rx /Tx switch in the signal path and using diodes, is acting as a noise generator. The noise could be driving the QRO stage as an independent source, or could be modulating the drive signal. These otherwise excellent switches can generate noise, but usually very little unless something goes 'ga ga'. Going from QRP to QRO could make such noise 'a problem' especially if something is amiss ('ga ga'). Spectral analysis should offer clues. This thought is based on a design problem with a 50kW ISB rig in which diode switching was used in QRP stages to interchange sidebands. 73, Geoff. GM4ESD ----- Original Message ----- From: "Fraser Robertson" <[hidden email]> To: <[hidden email]> Sent: Friday, March 18, 2005 1:26 AM Subject: [Elecraft] K2 phase noise > I want to get to the bottom of this > so that I can confidently use my K2 for QRO contesting. The rig has many > fine attributes and I take my hat off to Wayne and Eric for their excellent > design and production engineering. _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Fraser Robertson
It is my belief that a lot a technical aspects of Elecraft products are being
discussed 'Off Reflector' between specific interested individuals. I think that, because these discussions are not seen by the group, a lot of useful information is being missed. I would like to see these in-depth technical discussion treated in the same manner as the "what soldering iron should I use ?" type threads. Maybe the reflector could be sub-divided ? END OF RANT ... 73 G3RXQ On Fri, 18 Mar 2005 01:26:19 +0000, Fraser Robertson wrote: > Thank you for the responses and I'm pleased to get some discussion going on > > this subject on the reflector. Phase noise has been brought up before, but > not discussed in detail. As I said I've had personal emails about this so I > know I'm not on my own here. > > I should point out that my comments were not intended to 'slag off' the K2, > and I am not 'obsessed by numbers'. I don't expect the K2 to have lab grade > performance, nor to outperform high price rigs. My sole reason for looking > into this (believe me I've got better things to do) is due to complaints > about my signal on air. These have been from respected and technically > competent amateurs. I can go into detail if required. > > Several months ago I had some exchanges with Gary and Eric, and sent them > some analyser plots. More recently I've done comparisons at 300Hz from > carrier using a HP8640B as a reference, and I soon should be in a position > to produce more detailed plots of the close in phase noise. > > Although the comparisons I've made clearly show the K2 is inferior to the > MP, 870 and a home brew rig in this respect as stated, the phase noise > performance to me seems adequate, however, that doesn't explain the comments > I've received on air. I get very similar results with two K2's, one built > by me and another by GU3MBS, who is a very experienced K2 builder. Both > have all the latest mods. At other times I've received good reports, > possibly from less critical operators? I want to get to the bottom of this > so that I can confidently use my K2 for QRO contesting. The rig has many > fine attributes and I take my hat off to Wayne and Eric for their excellent > design and production engineering. > > By the way I've moved the K2 as far as practical from hum sources (>2') and > even tried enclosing it in a mu-metal shield, so I'm pretty confident that > magnetic modulation isn't the culprit. > > 73 Fraser G4BJM > > _________________________________________________________________ > It's fast, it's easy and it's free. Get MSN Messenger today! > http://www.msn.co.uk/messenger > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Hello boys!
I am playing around same problem for last two weeks. I had written to reflector but no one was interested to comment. I am using K2 for HF contesting with LL PA and for VHF contesting with transverter+ LL PA and i also want to have signal clean as much as possible. I was testing K2 on 14MHz with transverter and without it. For detailed information (in numbers) i still need some peace of equipment (step att).I was going from transverter output (abt 1mW sig) directly to a HF RX.Of course, i was increasing noise all over the band but that was not the problem.When i TX in SSB without modulation there are thousends of little birdies (none on CW) all over the entire band, way down from the level of carrier, but there. I am shure abt cause of that birdies is the 4MHz OSC on KSB2 board. What should be done in plus to take the TX noise further down? Suggestions are wellcome. Like Stewart, I would like to see the Top tehnicians to share the knowledge with us on this reflector. Have Fun! S55M-Adi ----- Original Message ----- From: "Stewart Baker" <[hidden email]> To: "Fraser Robertson" <[hidden email]>; <[hidden email]> Sent: Friday, March 18, 2005 8:15 AM Subject: Re: [Elecraft] K2 phase noise It is my belief that a lot a technical aspects of Elecraft products are being discussed 'Off Reflector' between specific interested individuals. I think that, because these discussions are not seen by the group, a lot of useful information is being missed. I would like to see these in-depth technical discussion treated in the same manner as the "what soldering iron should I use ?" type threads. Maybe the reflector could be sub-divided ? END OF RANT ... 73 G3RXQ On Fri, 18 Mar 2005 01:26:19 +0000, Fraser Robertson wrote: > Thank you for the responses and I'm pleased to get some discussion going on > > this subject on the reflector. Phase noise has been brought up before, but > not discussed in detail. As I said I've had personal emails about this so I > know I'm not on my own here. > > I should point out that my comments were not intended to 'slag off' the K2, > and I am not 'obsessed by numbers'. I don't expect the K2 to have lab grade > performance, nor to outperform high price rigs. My sole reason for looking > into this (believe me I've got better things to do) is due to complaints > about my signal on air. These have been from respected and technically > competent amateurs. I can go into detail if required. > > Several months ago I had some exchanges with Gary and Eric, and sent them > some analyser plots. More recently I've done comparisons at 300Hz from > carrier using a HP8640B as a reference, and I soon should be in a position > to produce more detailed plots of the close in phase noise. > > Although the comparisons I've made clearly show the K2 is inferior to the > MP, 870 and a home brew rig in this respect as stated, the phase noise > performance to me seems adequate, however, that doesn't explain the > I've received on air. I get very similar results with two K2's, one built > by me and another by GU3MBS, who is a very experienced K2 builder. Both > have all the latest mods. At other times I've received good reports, > possibly from less critical operators? I want to get to the bottom of this > so that I can confidently use my K2 for QRO contesting. The rig has many > fine attributes and I take my hat off to Wayne and Eric for their excellent > design and production engineering. > > By the way I've moved the K2 as far as practical from hum sources (>2') and > even tried enclosing it in a mu-metal shield, so I'm pretty confident that > magnetic modulation isn't the culprit. > > 73 Fraser G4BJM > > _________________________________________________________________ > It's fast, it's easy and it's free. Get MSN Messenger today! > http://www.msn.co.uk/messenger > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Fraser Robertson
In a message dated 18/03/05 01:27:47 GMT Standard Time, [hidden email] writes: I don't expect the K2 to have lab grade performance, nor to outperform high price rigs. My sole reason for looking into this (believe me I've got better things to do) is due to complaints about my signal on air. These have been from respected and technically competent amateurs. ------------------------------------------ >From a later posting by S55M-Adi it may appear there is some distortion reported from the K2's KSB2, SSB adapter under certain circumstances. Rather than resorting to "shotgun troubleshooting" a rather more thorough examination of the problem seems necessary. Firstly the basic QRP CW K2 TX is reported to be clean. Is it? Check that it is by removing all the additional boards from the K2, install the necessary straps/capacitors to return it to basic and test with a known good spectrum analyser that has the resolution capability or other test equipment as deemed appropriate. The spectrum analyser *must* be connected via suitable external attenuators to protect it's input and prevent the generation of non existent spurii within the instrument due to overload. Many an unwitting technician has been led astray with this point and can also result in the spectrum analyser having to be returned for repair to a burnt out front end and recalibration. An expensive process. If the K2 passes this test, install the KSB2 and start again with the testing. Follow this through board by board until the culprit for the perceived TX distortion is found. This would then be a good time to contact Elecraft Support or post on the Elecraft reflector for assistance with known specifics. Blanket criticism of the K2 is unlikely to succeed, only generating hostility from the satisfied users. It may be something as simple in some cases as wrong bias levels on the K2 PA transistors when that stage is used as part of the system. The K2 will still work on CW with no bias at all, but does sound extremely poor on SSB. This should show up in the testing and simple DVM tests will pin down the cause if this is so. Any non linearity in the TX signal path will degrade SSB where it has little if any effect on CW. Sensible testing with the knowledge of how to correctly use the test equipment should localise the problem. However having the best test equipment that money can buy still is no good if the person that is operating it does not know how to use it! In my latter years at work was involved in commissioning/acceptance testing of new communication sites that contained SDH digital microwave, SDH fiber optics plus all the various power systems and other support needed to run these systems. Due to the complex nature of the testing, the design engineers had thoughtfully documented precisely what test equipment should be used and all the settings for the various tests. Without this the job could have been rather chaotic with the engineers and technicians from many nations involved in the testing process. In my original posting I used the term "slagging". Fred, K6DGW pointed out to me quite rightly that the non UK members of the list may not understand this UK slang term. The nearest translation for this would be "castigate". Will follow the outcome of the reported problem with interest. Bob, G3VVT K2 #4168 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Fraser Robertson
Thanks for further comments. Yes the internal counter cable is removed. I
should also have made clear that my tests have been on unkeyed transmitted carrier, and have been with both the 100W pa on and off by appropriate setting of the power control. I have recently checked the pa bias setting. Tests were made via a 50 Ohm 50dB 100W load/pad. Both K2's have the following options fitted: internal 100W pa, KAF2 filter, 160m, plus my K2 has the 60m board and the club's has the SSB board. I have not attempted any SSB measurements and I have not tried removing the options. 73 Fraser G4BJM _________________________________________________________________ Want to block unwanted pop-ups? Download the free MSN Toolbar now! http://toolbar.msn.co.uk/ _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Fraser Robertson
In a message dated 18/03/05 07:33:11 GMT Standard Time, [hidden email] writes: For detailed information (in numbers) i still need some peace of equipment (step att).I was going from transverter output (abt 1mW sig) directly to a HF RX.Of course, i was increasing noise all over the band but that was not the problem.When i TX in SSB without modulation there are thousends of little birdies (none on CW) all over the entire band, way down from the level of carrier, but there. --------------------------------------- It is not considered good practice to feed effectively what is a low power transmitter directly into a receiver input as it can cause all kinds of distress to the receiver. 1mW or 0dBm is about 225mV PD across 50 ohms. The normal S9 level of 50uV PD is -73dBm. This means that 73dB over S9 is hitting the receiver front end. It will almost certainly show definite signs of distress! Try the test again with a suitable attenuator in line to bring the level down S9 or slightly above. i.e. -70 to -80dB of attenuation. Bob, G3VVT _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Geoffrey Mackenzie-Kennedy-2
Geoffrey, as I recall from tests I've done in the past, it doesn't appear to
be power related, and is not related to the KPA100. I'm not sure though if that completely rules out your suggestion? BTW, the K2/100 is usually putting out about 50W when driving my tube linear, so is just ticking along. Thanks / 73 Fraser G4BJM >From: "Geoffrey Mackenzie-Kennedy" <[hidden email]> > >There is the possibility that a Rx /Tx switch in the signal path and using >diodes, is acting as a noise generator. The noise could be driving the QRO >stage as an independent source, or could be modulating the drive signal. >These otherwise excellent switches can generate noise, but usually very >little unless something goes 'ga ga'. Going from QRP to QRO could make such >noise 'a problem' especially if something is amiss ('ga ga'). Spectral >analysis should offer clues. > _________________________________________________________________ Use MSN Messenger to send music and pics to your friends http://www.msn.co.uk/messenger _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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