Re: [Elecraft] K3 6m pre-amp
On Thu, 31 Jul 2008 09:10:54 -0700, Alan Bloom wrote: When you wire two chokes of different value in series, you almost always get a series-resonant hole in the attenuation somewhere between the parallel-resonant frequencies of the two chokes. It's not hard to see why that's true if you model each choke as an ideal inductor in parallel with a capacitor. But that's not an accurate model! If ferrite chokes are wound on the right ferrite material (the mix), they have a dominant RESISTIVE component in the frequency range of interest. While it IS important to consider the series L-C possibility, in REAL chokes, the resistive component can prevent this from being a problem. Indeed, this goes back to the original comment that the important property of a ferrite choke is RESISTANCE, NOT inductance! A properly designed choke (that is, right number of turns, winding style, and using the right material) can be made to have a high resistive impedance over at least an octave, and Fair-Rite's #31 is good for at least two octaves. Again, see my tutorial, which also shows how simple curve fitting in a spreadsheet can be used to come up with actual R, L, and C values from magnitude-only impedance data. It also shows a method of measurement that is much better than commonly accepted standards, like the HP Z meters and network analyzers when the unknown Z is high. 73, Jim Brown K9YC ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
On Wed, 30 Jul 2008 20:33:53 -0400, Jack Smith wrote: Yes, I have several ferrite core 2.5 mH chokes here, including the Hammond one you mention. There's a significant difference in high frequency performance of the pi wound on ceramic form versus the smaller pi-wound over ferrite and that's one of the things I'm hoping to illustrate in the article. The RFI and Ferrite tutorial on my website includes clear explanations of the nature of ferrite materials from a circuit point of view. You may find it helpful in explaining why your very correct in your analysis. You are welcome to cite it as a reference. http://audiosystemsgroup.com/RFI-Ham.pdf However -- ANY 2.5 mH choke has a good chance of looking capacitive at 50 MHz. 73, Jim Brown K9YC ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
Jim: Thank you for the reference. Indeed, the self-resonant frequency of the typical small (FT50 size) chokes I've wound are in the 5-10 MHz range, but at 100 MHz some (depending upon the core material) still show enough Z to be useful. For truly wideband 10 KHz - 100 MHz choke action, it's necessary to series two wound with different core material and turns, e.g., 35 turns on Steward 40 material for the 2.5 mH, followed by, e.g., 10 turns on FairRite 43 material for 50 MHz. You have to pay particular attention to the u' and u'' values of the ferrite material and how they change with frequency as this is a case where core loss at high frequencies can be good. Jack K8ZOA Jim Brown wrote: On Wed, 30 Jul 2008 20:33:53 -0400, Jack Smith wrote: Yes, I have several ferrite core 2.5 mH chokes here, including the Hammond one you mention. There's a significant difference in high frequency performance of the pi wound on ceramic form versus the smaller pi-wound over ferrite and that's one of the things I'm hoping to illustrate in the article. The RFI and Ferrite tutorial on my website includes clear explanations of the nature of ferrite materials from a circuit point of view. You may find it helpful in explaining why your very correct in your analysis. You are welcome to cite it as a reference. http://audiosystemsgroup.com/RFI-Ham.pdf However -- ANY 2.5 mH choke has a good chance of looking capacitive at 50 MHz. 73, Jim Brown K9YC ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
When you wire two chokes of different value in series, you almost always get a series-resonant hole in the attenuation somewhere between the parallel-resonant frequencies of the two chokes. It's not hard to see why that's true if you model each choke as an ideal inductor in parallel with a capacitor. So you need to design the combination so that the series-resonant frequency falls somewhere unimportant. Al N1AL On Thu, 2008-07-31 at 09:14, Jack Smith wrote: Jim: Thank you for the reference. Indeed, the self-resonant frequency of the typical small (FT50 size) chokes I've wound are in the 5-10 MHz range, but at 100 MHz some (depending upon the core material) still show enough Z to be useful. For truly wideband 10 KHz - 100 MHz choke action, it's necessary to series two wound with different core material and turns, e.g., 35 turns on Steward 40 material for the 2.5 mH, followed by, e.g., 10 turns on FairRite 43 material for 50 MHz. You have to pay particular attention to the u' and u'' values of the ferrite material and how they change with frequency as this is a case where core loss at high frequencies can be good. Jack K8ZOA Jim Brown wrote: On Wed, 30 Jul 2008 20:33:53 -0400, Jack Smith wrote: Yes, I have several ferrite core 2.5 mH chokes here, including the Hammond one you mention. There's a significant difference in high frequency performance of the pi wound on ceramic form versus the smaller pi-wound over ferrite and that's one of the things I'm hoping to illustrate in the article. The RFI and Ferrite tutorial on my website includes clear explanations of the nature of ferrite materials from a circuit point of view. You may find it helpful in explaining why your very correct in your analysis. You are welcome to cite it as a reference. http://audiosystemsgroup.com/RFI-Ham.pdf However -- ANY 2.5 mH choke has a good chance of looking capacitive at 50 MHz. 73, Jim Brown K9YC ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
Indeed such is the case, and it is quite pronounced with high Q inductors. You may wish, however, to model and/or measure two series chokes when both are wound on lossy ferrite material. The response looks quite different. The resistance in parallel with the inductors radically modifies the response when the material causes the inductor Q to be 1. I'll E-mail you some early measurements and a quick simulation plots. Jack K8ZOA Alan Bloom wrote: When you wire two chokes of different value in series, you almost always get a series-resonant hole in the attenuation somewhere between the parallel-resonant frequencies of the two chokes. It's not hard to see why that's true if you model each choke as an ideal inductor in parallel with a capacitor. So you need to design the combination so that the series-resonant frequency falls somewhere unimportant. Al N1AL On Thu, 2008-07-31 at 09:14, Jack Smith wrote: Jim: Thank you for the reference. Indeed, the self-resonant frequency of the typical small (FT50 size) chokes I've wound are in the 5-10 MHz range, but at 100 MHz some (depending upon the core material) still show enough Z to be useful. For truly wideband 10 KHz - 100 MHz choke action, it's necessary to series two wound with different core material and turns, e.g., 35 turns on Steward 40 material for the 2.5 mH, followed by, e.g., 10 turns on FairRite 43 material for 50 MHz. You have to pay particular attention to the u' and u'' values of the ferrite material and how they change with frequency as this is a case where core loss at high frequencies can be good. Jack K8ZOA Jim Brown wrote: On Wed, 30 Jul 2008 20:33:53 -0400, Jack Smith wrote: Yes, I have several ferrite core 2.5 mH chokes here, including the Hammond one you mention. There's a significant difference in high frequency performance of the pi wound on ceramic form versus the smaller pi-wound over ferrite and that's one of the things I'm hoping to illustrate in the article. The RFI and Ferrite tutorial on my website includes clear explanations of the nature of ferrite materials from a circuit point of view. You may find it helpful in explaining why your very correct in your analysis. You are welcome to cite it as a reference. http://audiosystemsgroup.com/RFI-Ham.pdf However -- ANY 2.5 mH choke has a good chance of looking capacitive at 50 MHz. 73, Jim Brown K9YC ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
I've been looking for a pair of RFC's to bleed the static off of my parallel feedline to ground. Have a couple of resistors, but would prefer a lower resistance DC path to ground. The antenna is used for the 160 through 6 meter ham bands and general coverage receiving so having something that would have a high impedance from 10 kHz to 100 MHz would be great. Would this type of choke be suitable? Darrell VA7TO K2 #5093 On Thursday 31 July 2008 09:14, Jack Smith wrote: Jim: Thank you for the reference. Indeed, the self-resonant frequency of the typical small (FT50 size) chokes I've wound are in the 5-10 MHz range, but at 100 MHz some (depending upon the core material) still show enough Z to be useful. For truly wideband 10 KHz - 100 MHz choke action, it's necessary to series two wound with different core material and turns, e.g., 35 turns on Steward 40 material for the 2.5 mH, followed by, e.g., 10 turns on FairRite 43 material for 50 MHz. You have to pay particular attention to the u' and u'' values of the ferrite material and how they change with frequency as this is a case where core loss at high frequencies can be good. Jack K8ZOA Jim Brown wrote: On Wed, 30 Jul 2008 20:33:53 -0400, Jack Smith wrote: Yes, I have several ferrite core 2.5 mH chokes here, including the Hammond one you mention. There's a significant difference in high frequency performance of the pi wound on ceramic form versus the smaller pi-wound over ferrite and that's one of the things I'm hoping to illustrate in the article. The RFI and Ferrite tutorial on my website includes clear explanations of the nature of ferrite materials from a circuit point of view. You may find it helpful in explaining why your very correct in your analysis. You are welcome to cite it as a reference. http://audiosystemsgroup.com/RFI-Ham.pdf However -- ANY 2.5 mH choke has a good chance of looking capacitive at 50 MHz. 73, Jim Brown K9YC ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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 -- Darrell Bellerive Amateur Radio Stations VA7TO and VE7CLA Grand Forks, British Columbia, Canada ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
Good point. That's why ferrite beads make good parasitic suppressors - at VHF frequencies they act more like resistors than inductors. Where I ran into this problem was trying to come up with a plate choke for a kilowatt amplifier that would work from 1.8 to 19.7 MHz. The high inductance needed for the 160 meter band pretty much guaranteed poor performance at 10 meters. I couldn't make the choke lossy because it would burn up at those power levels. The solution was to use two chokes in series and select values that resulted in a series resonance that fell safely in between amateur bands. Al N1AL On Thu, 2008-07-31 at 10:34, Jack Smith wrote: Indeed such is the case, and it is quite pronounced with high Q inductors. You may wish, however, to model and/or measure two series chokes when both are wound on lossy ferrite material. The response looks quite different. The resistance in parallel with the inductors radically modifies the response when the material causes the inductor Q to be 1. I'll E-mail you some early measurements and a quick simulation plots. Jack K8ZOA Alan Bloom wrote: When you wire two chokes of different value in series, you almost always get a series-resonant hole in the attenuation somewhere between the parallel-resonant frequencies of the two chokes. It's not hard to see why that's true if you model each choke as an ideal inductor in parallel with a capacitor. So you need to design the combination so that the series-resonant frequency falls somewhere unimportant. Al N1AL On Thu, 2008-07-31 at 09:14, Jack Smith wrote: Jim: Thank you for the reference. Indeed, the self-resonant frequency of the typical small (FT50 size) chokes I've wound are in the 5-10 MHz range, but at 100 MHz some (depending upon the core material) still show enough Z to be useful. For truly wideband 10 KHz - 100 MHz choke action, it's necessary to series two wound with different core material and turns, e.g., 35 turns on Steward 40 material for the 2.5 mH, followed by, e.g., 10 turns on FairRite 43 material for 50 MHz. You have to pay particular attention to the u' and u'' values of the ferrite material and how they change with frequency as this is a case where core loss at high frequencies can be good. Jack K8ZOA Jim Brown wrote: On Wed, 30 Jul 2008 20:33:53 -0400, Jack Smith wrote: Yes, I have several ferrite core 2.5 mH chokes here, including the Hammond one you mention. There's a significant difference in high frequency performance of the pi wound on ceramic form versus the smaller pi-wound over ferrite and that's one of the things I'm hoping to illustrate in the article. The RFI and Ferrite tutorial on my website includes clear explanations of the nature of ferrite materials from a circuit point of view. You may find it helpful in explaining why your very correct in your analysis. You are welcome to cite it as a reference. http://audiosystemsgroup.com/RFI-Ham.pdf However -- ANY 2.5 mH choke has a good chance of looking capacitive at 50 MHz. 73, Jim Brown K9YC ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
On Thu, 31 Jul 2008 09:42:16 -0700, Alan Bloom wrote: That's why ferrite beads make good parasitic suppressors - at VHF frequencies they act more like resistors than inductors. EXACTLY! The equivalent circuit of a wire going through a ferrite bead is a low Q parallel resonant circuit. (For some ferrite materials, its two parallel resonant circuits in series.) When we wind multiple turns through or around a core, we increase the capacitance between turns and multiply the inductance and loss by N squared, both of which serve to move the resonance down in frequency and increase the R at resonance. For all practical purposes, Q changes only to the extent that u' and u'' are changing with frequency. Thus, a material like Fair-Rite #43 which for most form factors has a resonance around 200 MHz can provide effective suppression at HF by winding multiple turns through it. The tutorial includes a development of the equivalent circuit (this work is original with me, and was first published in an AES Paper, also on my website). 73, Jim Brown K9YC ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: Re: [Elecraft] K3 6m pre-amp
Try Antique Electronic Supply (www.tubesandmore.com). Their 2.5 mH is good for 160 mA, made by Hammond, core material is ferrite, 3 pi-windings, diameter 0.469, price $3.95. Erik K7TV Another used-to-be-common part is a 2.5 mH RF choke, pi wound on a ceramic form. After a lengthy search, I found Hammond still makes these, only to learn that they were discontinued earlier this year. I managed to get one (at a price of $14) and it's good that I only needed one to use as a comparison reference for a QEX article I'm working on. -- View this message in context: http://n2.nabble.com/K3-External-2nd-receiver-with-KXV3-and-6m-pre-amp--tp587908p661341.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
Yes, I have several ferrite core 2.5 mH chokes here, including the Hammond one you mention. There's a significant difference in high frequency performance of the pi wound on ceramic form versus the smaller pi-wound over ferrite and that's one of the things I'm hoping to illustrate in the article. Hence, I needed a genuine 2.5 mH National Radio style choke. Jack K7TV wrote: Try Antique Electronic Supply (www.tubesandmore.com). Their 2.5 mH is good for 160 mA, made by Hammond, core material is ferrite, 3 pi-windings, diameter 0.469, price $3.95. Erik K7TV Another used-to-be-common part is a 2.5 mH RF choke, pi wound on a ceramic form. After a lengthy search, I found Hammond still makes these, only to learn that they were discontinued earlier this year. I managed to get one (at a price of $14) and it's good that I only needed one to use as a comparison reference for a QEX article I'm working on. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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] K3 6m pre-amp
To enhance the 6 meter performance of my K3 I built the U310 preamplifier as described on N6CA's website: http://www.ham-radio.com/n6ca/50MHz/50appnotes/U310.html Tuned up on an HP8970A noise figure meter it gives 11.2 dB gain and NF=1.3 dB. The receiver's performance on weak signals was significantly improved. I already had the parts but cost should not exceed $30.00 to duplicate this preamphard to beat. I have not done measurements on the radio/preamp combination to determine any negative effect on the receiver performance but the K3, which always performed well in the presence of strong signals, continues to do so. John, N6AX K3 #567 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
Haven't really had time to use my K3 on 50MHz, but when I tried it the sensitivity seemed quite a bit down on my K2/KXV50 combination. Unfortunately I have sold the KXV50, so I can't do an A/B comparison. Is this what the preamp is meant to address ? 73 Stewart G3RXQ On Sun, 23 Mar 2008 19:51 + (GMT Standard Time), Trevor Smithers wrote: Anyone have any new information on the 6m pre-amp for the K3. I'm aware that it was being tested back in January - just wondering when its likely to become available. Hopefully it will be in kit form. 73 to all Trevor G0KTN ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
Yes, wondering how that will affect connection of a XV144? -- 73 de M0XDF / K3 #174 On 24 Mar 2008, at 10:25, Trevor Smithers wrote: Is this what the preamp is meant to address Have a look at the K3 Test from Bavaria pdf half way down page 11 - note from Wayne. http://www.bavarian-contest-club.de/projects/K3_english.pdf 73 to all Trevor G0KTN ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
Is this what the preamp is meant to address Have a look at the K3 Test from Bavaria pdf half way down page 11 - note from Wayne. http://www.bavarian-contest-club.de/projects/K3_english.pdf 73 to all Trevor G0KTN ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
Trevor Smithers wrote: Is this what the preamp is meant to address Have a look at the K3 Test from Bavaria pdf half way down page 11 - note from Wayne. http://www.bavarian-contest-club.de/projects/K3_english.pdf It attaches directly to the RX ANT IN and OUT jacks. Does that mean you need to have the KXV3 module to use this preamp, or does it mean the preamp uses the internal connections that the KXV3 would use? I wouldn't have expected to need the KXV3 module unless I actually wanted to use external transverters to work bands above 6m. - Julian, G4ILO K3 s/n: 222 K2 s/n: 392 G4ILO's Shack: www.g4ilo.com Zerobeat Ham Forums: www.zerobeat.net/smf -- View this message in context: http://www.nabble.com/K3-6m-pre-amp-tp16240611p16248115.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
Thanks Trevor, I can't see any comment made by the BCC re the 6m sensitivity, only Wayne's response. I have checked my K3 on all other bands, and it is spot on the money. Unfortunately I have no accurate signal sources for 50Mhz. Now my friend is back from a holiday in Australia I can make a comparison with his Japanese Black Box. At the moment, based on my memory of a local beacon received on the K2/KXV50 is 3-4 S points down on my K3 . 73 Stewart G3RXQ On Mon, 24 Mar 2008 10:25 + (GMT Standard Time), Trevor Smithers wrote: Is this what the preamp is meant to address Have a look at the K3 Test from Bavaria pdf half way down page 11 - note from Wayne. http://www.bavarian-contest-club.de/projects/K3_english.pdf 73 to all Trevor G0KTN ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
My 6m setup is not the greatest. I have a beam in the garage, but to put that up means moving the HF antenna, so it will have to wait for the better weather. Yes, I had just tried the ant vs dummy load comparison. The noise level increases with the antenna connected, but whether that is due to band or local electrical noise I can't be sure. It is probably that I have got used to seeing a significant noise reading on the S meter on the bands below 30MHz ! 73 Stewart G3RXQ On Mon, 24 Mar 2008 12:19:46 +, Brendan Minish wrote: In my quiet rural location with a 7 element long yagi fed with feeder totalling about 0.5dB of feeder loss, I find that the K3 is sensitive enough (just) to hear to the band noise floor. My Icom 7800 was more sensitive on 6m ( a superb 6m radio in general) but since the K3 is sensitive enough to hear to the band noise floor I suspect that adding a premap in my case is not going to help. Eavesdropping on EME QSO's ( i have yet to do EME on 6m with the K3) seems to indicate that the in my setup adding a preamp is going to make little or no difference. A simple test is to compare the noise level of a Dummy load with the noise level received on an antenna. If you hear more nose on the antenna than you do on the Dummy load then it its unlikely that adding a preamp will help in your situation. 73 Brendan EI6IZ On Mon, 2008-03-24 at 08:01 +, Stewart Baker wrote: Haven't really had time to use my K3 on 50MHz, but when I tried it the sensitivity seemed quite a bit down on my K2/KXV50 combination. Unfortunately I have sold the KXV50, so I can't do an A/B comparison. Is this what the preamp is meant to address ? 73 Stewart G3RXQ On Sun, 23 Mar 2008 19:51 + (GMT Standard Time), Trevor Smithers wrote: Anyone have any new information on the 6m pre-amp for the K3. I'm aware that it was being tested back in January - just wondering when its likely to become available. Hopefully it will be in kit form. 73 to all Trevor G0KTN ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
In my quiet rural location with a 7 element long yagi fed with feeder totalling about 0.5dB of feeder loss, I find that the K3 is sensitive enough (just) to hear to the band noise floor. My Icom 7800 was more sensitive on 6m ( a superb 6m radio in general) but since the K3 is sensitive enough to hear to the band noise floor I suspect that adding a premap in my case is not going to help. Eavesdropping on EME QSO's ( i have yet to do EME on 6m with the K3) seems to indicate that the in my setup adding a preamp is going to make little or no difference. A simple test is to compare the noise level of a Dummy load with the noise level received on an antenna. If you hear more nose on the antenna than you do on the Dummy load then it its unlikely that adding a preamp will help in your situation. 73 Brendan EI6IZ On Mon, 2008-03-24 at 08:01 +, Stewart Baker wrote: Haven't really had time to use my K3 on 50MHz, but when I tried it the sensitivity seemed quite a bit down on my K2/KXV50 combination. Unfortunately I have sold the KXV50, so I can't do an A/B comparison. Is this what the preamp is meant to address ? 73 Stewart G3RXQ On Sun, 23 Mar 2008 19:51 + (GMT Standard Time), Trevor Smithers wrote: Anyone have any new information on the 6m pre-amp for the K3. I'm aware that it was being tested back in January - just wondering when its likely to become available. Hopefully it will be in kit form. 73 to all Trevor G0KTN ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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 -- Brendan Minish, Westnet, Technology House, Castlebar, Co Mayo. 1850 930305 Registered in Ireland, Company no. 399770 Western Broadband Networks Limited, T/A WestNet -- Don‘t complain. Nobody will understand. Or care. And certainly don‘t try to fix the situation yourself. It‘s dangerous. Leave it to a highly untrained, unqualified, expendable professional. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
...I wouldn't have expected to need the KXV3 module unless I actually wanted to use external transverters to work bands above 6m. Note that the KXV3 provides five BNC connectors. Two (XVTR IN and XVTR OUT) are dedicated for transverter use, or other applications for which you need a nominal 1 mW signal. One (IF OUT) is dedicated for tapping the *.215 Mhz IF, for such things as a panadaptor. Two are dedicated for modifying the receive signal path (RX ANT IN and RX ANT OUT). This can accommodate a receive only antenna (such as a beverage for MF work), filed day filters for multi-multi contest stations, or a 6M preamp, among other things. Thus, the KXV3 is not just for transverters, but for significantly added flexibility to the basic K3 for a variety of purposes. 73, Lyle KK7P ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
Haven't really had time to use my K3 on 50MHz, but when I tried it the sensitivity seemed quite a bit down on my K2/KXV50 combination. Unfortunately I have sold the KXV50, so I can't do an A/B comparison. Is this what the preamp is meant to address ? The 6m preamp, when available, is meant to help in those cases where a lower noise figure at the receiver input (or lower receiver temperature if you prefer to think of it that way) coupled with the required additional front end gain to provide that lower noise figure, would be expected to provide improved receive performance as determined by the station system design. Your 6m receiving system may or may not benefit from this. It depends entirely on your station's design and where the K3 as a component fits into that design. 73, Lyle KK7P ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
Yes, wondering how that will affect connection of a XV144? No impact. The XV144 attaches to different BNC connectors on the KXV3. YOU can have an XV144, XV22 and XV432 attached to the K3 and still connect (or not connect) the 6m preamp as you desire. 73, Lyle KK7P ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
Lyle Johnson-6 wrote: Thus, the KXV3 is not just for transverters, but for significantly added flexibility to the basic K3 for a variety of purposes. OK. The XV nomenclature is a bit confusing. I could have said that I would not have expected to need a KXV3 to use 6m when the K3 is supposed to support it already. But judging by the last couple of comments on sensitivity perhaps a preamp isn't really needed anyway. - Julian, G4ILO K3 s/n: 222 K2 s/n: 392 G4ILO's Shack: www.g4ilo.com Zerobeat Ham Forums: www.zerobeat.net/smf -- View this message in context: http://www.nabble.com/K3-6m-pre-amp-tp16240611p16252775.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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] K3 6m pre-amp
I've just done an A/B comparison between my K3 and my Kenwood TS-480SAT. I had the pre-amp switched on in both transceivers. On the 480 I was able to comfortably hear a signal from my signal generator some 10 dB lower in level on the 480 than I could on the K3, which is quite a difference. I think the often quoted MDS (minimum discernible signal) makes the specification appear better than it really is and is not realistic. MDS is a measure of the signal that increases the output of the receiver by 3 dB when the signal generators output is turned on. You couldn't copy by ear a signal of that level except for the slowest of Morse keying and then it would be very hard going. The old fashioned signal level that gives a signal to noise ratio of 10 dB is more meaningful, as a 10 dB above the noise signal is a comfortable listening level that we can all equate to. I had done earlier A/B comparisons between the K3 and 480 where I didn't think there was a difference, I must have mistakenly not use the 480 pre-amp... 73 Dave, G4AON K3/100 #80 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
On Mon, 24 Mar 2008 07:05:53 -0700, Lyle Johnson wrote: Haven't really had time to use my K3 on 50MHz, but when I tried it the sensitivity seemed quite a bit down on my K2/KXV50 combination. Unfortunately I have sold the KXV50, so I can't do an A/B comparison. Is this what the preamp is meant to address ? The 6m preamp, when available, is meant to help in those cases where a lower noise figure at the receiver input (or lower receiver temperature if you prefer to think of it that way) coupled with the required additional front end gain to provide that lower noise figure, would be expected to provide improved receive performance as determined by the station system design. Your 6m receiving system may or may not benefit from this. It depends entirely on your station's design and where the K3 as a component fits into that design. 73, Lyle KK7P QSL Lyle, I think what it all goes to prove is what a good front end the XV50 (not KXV50 as in my previous) has. The only problem I see here with having a pre-amp connected to the KXV3 is that I also use the RX ant input for a HF receive antenna. I suspect that I would need to implement some external relay switching for that.. 73 Stewart G3RXQ ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
Hallo, I can't see any comment made by the BCC re the 6m sensitivity, only Wayne's response. I am working on the translation of a much delayed update of the BCC report. In the mean time we have done MDS measurements for various bands: - Bandw Preampw/o Preamp 160m-129dBm -137dBm 80m -133dBm -138dBm 40m -133dBm -138dBm 20m -134dBm -138dBm 15m -132dBm -137dBm 10m -130dBm -137dBm 6m -129dBm -134dBm Table 2: MDS of the K3 at 400Hz - vy 73 de toby -- DD5FZ (ex 4n6fz, dj7mgq, dg5mgq, dd5fz) K2 #885 K2/100 #3248 K3/100 #67 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
Toby: Is your data reversed? Gregg -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Toby Deinhardt Sent: Monday, March 24, 2008 10:41 AM To: Stewart Baker Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3 6m pre-amp Hallo, I can't see any comment made by the BCC re the 6m sensitivity, only Wayne's response. I am working on the translation of a much delayed update of the BCC report. In the mean time we have done MDS measurements for various bands: - Bandw Preampw/o Preamp 160m-129dBm -137dBm 80m -133dBm -138dBm 40m -133dBm -138dBm 20m -134dBm -138dBm 15m -132dBm -137dBm 10m -130dBm -137dBm 6m -129dBm -134dBm Table 2: MDS of the K3 at 400Hz - vy 73 de toby -- DD5FZ (ex 4n6fz, dj7mgq, dg5mgq, dd5fz) K2 #885 K2/100 #3248 K3/100 #67 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
I would certainly say so. :-) Of course, he could be using the famous Larson E. Rapp Magic Band Preamp, which is so sensitive that its MDS actually reflects off of the Absolute Zero Noise Floor (see previous art on this subject) and becomes inverted. Truly, uh, incredible. :-) Bill W5WVO Gregg W6IZT wrote: Toby: Is your data reversed? Gregg -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Toby Deinhardt Sent: Monday, March 24, 2008 10:41 AM To: Stewart Baker Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3 6m pre-amp Hallo, I can't see any comment made by the BCC re the 6m sensitivity, only Wayne's response. I am working on the translation of a much delayed update of the BCC report. In the mean time we have done MDS measurements for various bands: - Bandw Preampw/o Preamp 160m-129dBm -137dBm 80m -133dBm -138dBm 40m -133dBm -138dBm 20m -134dBm -138dBm 15m -132dBm -137dBm 10m -130dBm -137dBm 6m -129dBm -134dBm Table 2: MDS of the K3 at 400Hz - vy 73 de toby ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
Dave, If I do the conversion to microvolts, it indicates 0.8 microvolts for no preamp and 0.04 microvolts for a preamp (I think the column headings are reversed) I believe MDS is a 3db s/n ratio. For comparison. My IC706IIG has the following 50MHz specs 0.12 microvolts for 10 db s/n ratio. Filter unspecificed, mode SSB/CW, preamp on. My guess it is the stock (2.7KHz?) filter What it really measures, I don't know. I know why they didn't use the narrower available CW filters for the ICOM specs. The 300Hz filter has a lot of uncompensated for loss. So much so I can't use it on 6M CW for any weak signal work. All that aside. Trying to put the two on an equal footing. Say 400Hz, 3db S/N indicates the 706 would come in at about (preamp on, 400Hz lossless filter, 3db S/N) yields -131 dbm (if I did the math right) One thing for sure, one can't compare S-meter readings from rig to rig. It has to be some kind of measurement with attenuators or lab equipment- - like you did with the lab generator. What are the 480 specs on 6M? I do disagree with a CW op not being able to copy a signal with a 3db s/n ratio. In fact, decent operators can copy CW signals several db below the noise. 73 de Brian/K3KO -- Hallo, I can't see any comment made by the BCC re the 6m sensitivity, only Wayne's response. I am working on the translation of a much delayed update of the BCC report. In the mean time we have done MDS measurements for various bands: - Bandw Preampw/o Preamp 160m-129dBm -137dBm 80m -133dBm -138dBm 40m -133dBm -138dBm 20m -134dBm -138dBm 15m -132dBm -137dBm 10m -130dBm -137dBm 6m -129dBm -134dBm Table 2: MDS of the K3 at 400Hz - vy 73 de toby -- DD5FZ (ex 4n6fz, dj7mgq, dg5mgq, dd5fz) Dave G4AON wrote: I've just done an A/B comparison between my K3 and my Kenwood TS-480SAT. I had the pre-amp switched on in both transceivers. On the 480 I was able to comfortably hear a signal from my signal generator some 10 dB lower in level on the 480 than I could on the K3, which is quite a difference. I think the often quoted MDS (minimum discernible signal) makes the specification appear better than it really is and is not realistic. MDS is a measure of the signal that increases the output of the receiver by 3 dB when the signal generators output is turned on. You couldn't copy by ear a signal of that level except for the slowest of Morse keying and then it would be very hard going. The old fashioned signal level that gives a signal to noise ratio of 10 dB is more meaningful, as a 10 dB above the noise signal is a comfortable listening level that we can all equate to. I had done earlier A/B comparisons between the K3 and 480 where I didn't think there was a difference, I must have mistakenly not use the 480 pre-amp... 73 Dave, G4AON K3/100 #80 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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 -- View this message in context: http://www.nabble.com/K3-6m-pre-amp-tp16252928p16254955.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
If I interpret you correctly, Stewart, perhaps the external switching wouldn't be necessary of the Elecraft preamp had remotely selected bypass implemented. Bruce, NM5B QSL Lyle, I think what it all goes to prove is what a good front end the XV50 (not KXV50 as in my previous) has. The only problem I see here with having a pre-amp connected to the KXV3 is that I also use the RX ant input for a HF receive antenna. I suspect that I would need to implement some external relay switching for that.. 73 Stewart G3RXQ ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
yes, thanks, I'd forgot it had 5 connectors as per your other post. I think this is just another example of Elecraft being future proof. now for the flames saying the 6m performance should have been better in the first place :-) -- 73 de M0XDF / K3 #174 On 24 Mar 2008, at 14:09, Lyle Johnson wrote: Yes, wondering how that will affect connection of a XV144? No impact. The XV144 attaches to different BNC connectors on the KXV3. YOU can have an XV144, XV22 and XV432 attached to the K3 and still connect (or not connect) the 6m preamp as you desire. 73, Lyle KK7P ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
Upps - Thanks for catching that! Yes they are swapped! vy 73 de toby Stewart Baker wrote: Thanks Toby, It shows that the K3 has a worse (not even equal) MDS at 50MHz than on the lower bands. Are the column headings swapped ? 73 Stewart G3RXQ On Mon, 24 Mar 2008 15:41:24 +0100, Toby Deinhardt wrote: Hallo, I can't see any comment made by the BCC re the 6m sensitivity, only Wayne's response. I am working on the translation of a much delayed update of the BCC report. In the mean time we have done MDS measurements for various bands: - Bandw Preampw/o Preamp 160m-129dBm -137dBm 80m -133dBm -138dBm 40m -133dBm -138dBm 20m -134dBm -138dBm 15m -132dBm -137dBm 10m -130dBm -137dBm 6m -129dBm -134dBm Table 2: MDS of the K3 at 400Hz - vy 73 de toby ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
Not 0.8 it is 0.08 microvolts for no preamp K3KO K3KO wrote: Dave, If I do the conversion to microvolts, it indicates 0.8 microvolts for no preamp and 0.04 microvolts for a preamp (I think the column headings are reversed) I believe MDS is a 3db s/n ratio. For comparison. My IC706IIG has the following 50MHz specs 0.12 microvolts for 10 db s/n ratio. Filter unspecificed, mode SSB/CW, preamp on. My guess it is the stock (2.7KHz?) filter What it really measures, I don't know. I know why they didn't use the narrower available CW filters for the ICOM specs. The 300Hz filter has a lot of uncompensated for loss. So much so I can't use it on 6M CW for any weak signal work. All that aside. Trying to put the two on an equal footing. Say 400Hz, 3db S/N indicates the 706 would come in at about (preamp on, 400Hz lossless filter, 3db S/N) yields -131 dbm (if I did the math right) One thing for sure, one can't compare S-meter readings from rig to rig. It has to be some kind of measurement with attenuators or lab equipment- - like you did with the lab generator. What are the 480 specs on 6M? I do disagree with a CW op not being able to copy a signal with a 3db s/n ratio. In fact, decent operators can copy CW signals several db below the noise. 73 de Brian/K3KO -- Hallo, I can't see any comment made by the BCC re the 6m sensitivity, only Wayne's response. I am working on the translation of a much delayed update of the BCC report. In the mean time we have done MDS measurements for various bands: - Bandw Preampw/o Preamp 160m-129dBm -137dBm 80m -133dBm -138dBm 40m -133dBm -138dBm 20m -134dBm -138dBm 15m -132dBm -137dBm 10m -130dBm -137dBm 6m -129dBm -134dBm Table 2: MDS of the K3 at 400Hz - vy 73 de toby -- DD5FZ (ex 4n6fz, dj7mgq, dg5mgq, dd5fz) Dave G4AON wrote: I've just done an A/B comparison between my K3 and my Kenwood TS-480SAT. I had the pre-amp switched on in both transceivers. On the 480 I was able to comfortably hear a signal from my signal generator some 10 dB lower in level on the 480 than I could on the K3, which is quite a difference. I think the often quoted MDS (minimum discernible signal) makes the specification appear better than it really is and is not realistic. MDS is a measure of the signal that increases the output of the receiver by 3 dB when the signal generators output is turned on. You couldn't copy by ear a signal of that level except for the slowest of Morse keying and then it would be very hard going. The old fashioned signal level that gives a signal to noise ratio of 10 dB is more meaningful, as a 10 dB above the noise signal is a comfortable listening level that we can all equate to. I had done earlier A/B comparisons between the K3 and 480 where I didn't think there was a difference, I must have mistakenly not use the 480 pre-amp... 73 Dave, G4AON K3/100 #80 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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 -- View this message in context: http://www.nabble.com/K3-6m-pre-amp-tp16252928p16263724.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: [Elecraft] K3 6m pre-amp
Hi Bob, It looks like you may have gotten your column headings reveresed :-) Yep - mea culpa... I read the K3 comparison the BCC group did earlier. You mentioned you would be trying out the K3 in the 160m contests. Yes we have and we have also used it in several other contests. Did you ever write up a report on that? I'm very curious to see your experiences on 160m with the K3. Not really, but to give you a feel for the general opinion of the BCC members who have used it: The K3 is a very capable contest rig. During the Russian DX contest, DL8OBD said he was not always happy with the AGC. He was working mainly CW and I did the SSB parts. I have not had a chance to talk with him after the contest yet, to find exactly what he did not like. All others, e.g. DL2MLU, DL6RAI, DK4YJ, DG7RO, DK3YD, etc., have been happy with the default values for and action of the AGC in CW and/or SSB. One wierd comment was that one OM did not like the way some of the knobs, e.g. PWR/CMP, feel. He said they feel wobbly to him. This has never bothered me. I can not remember any other negative comments, apart from the SSB modulation, which is well on its way to being solved in the last couple versions of the firmware. I hope the SSB power level offset will solved soon as well. What else can I say... During CQ 160m CW the K3 was used as a secondary RX. I did not partake in this contest but was told that everything which could be heard with the K3 could also be heard with a TS-850 and vice-versa. And during the 160m SSB contest, the highlight was DL6RAI and DG7RO working Ducie Island about 20 minutes or so after our local sunrise! We could hear them working stations in the south western part of the USA, and that they heard us says a lot about the rigs (K3s), antennas and operators at both ends. Without having a direct A/B comparison, during a 2-meter contest I really had the strong impression I could still read SSB signals, which I would not have been able to read with a TS-850 as the backend. The transverter at our club station is a bit on the old side, but still quite good. The 2m contest was otherwise a bit of a disappointment, because the TX/RX switch of the 144MHz 500W PA malfunctioned. I was also very happy with the K3 in the RTTY WPX. I could get very close to a very strong local station and still dig out weak signals. The 400Hz roofing filter performed well in this role from our local club station, where we have a large contest station less than a mile away. I did not miss having a smaller roofing bandwidth. The dual passband RTTY DSP filter was not as useful as I had expected. It was nice to have, but I don't think I ever really needed it. vy 73 de toby -- DD5FZ (ex 4n6fz, dj7mgq, dg5mgq, dd5fz) K2 #885 K2/100 #3248 K3/100 #67 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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] K3 6m pre-amp
Anyone have any new information on the 6m pre-amp for the K3. I'm aware that it was being tested back in January - just wondering when its likely to become available. Hopefully it will be in kit form. 73 to all Trevor G0KTN ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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] K3 6m pre-amp
Trevor - Until Elecraft gets a 6 meter preamp out, try building one of your own: http://www.ham-radio.com/n6ca/50MHz/50appnotes/U310.html This is about as simple as it gets, inexpensive, and offers as good noise figure performance as you are likely to need. It is a proven design that will offer a noticeable improvement to the K3 noise figure, if your noise environment can support it. That said, how do you like the K3 on 6? - Duffey -- KK6MC James Duffey Cedar Crest NM ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
