Re: [Elecraft] Hum Coupling
Thank you! Yes, this is commercial Mu Metal shielding, but no the same brand. The magnetic permeability is 1,000,000 and it can be bent. See the link to lessemf.com in the original message for purchase info. I got $5 worth. It is fun stuff. Leigh. On Tue, 4 Jan 2005 3:23 pm, Stuart Rohre wrote: Aluminum foil has very slight magnetic shielding, but there is commercial mu metal foil that is very expensive but very good. Thin sheet metal is cheaper and more readily found. Check it with a magnet to see if it will work as magnetic shield. If magnet sticks it is steel or ferrous (shield ability) material. -Stuart K5KVH ___ 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] Hum Coupling
Aluminum foil has very slight magnetic shielding, but there is commercial mu metal foil that is very expensive but very good. Thin sheet metal is cheaper and more readily found. Check it with a magnet to see if it will work as magnetic shield. If magnet sticks it is steel or ferrous (shield ability) material. -Stuart K5KVH
Re: [Elecraft] Hum Coupling
I remembered this thread and when I was looking at the slashdot article on RF shielding paint the other day, remembered that I had problems with my K2 and a flourescent Ott light, presumably from its transformer. I ordered some Metglas tape from these folks, and tried a few layers of it around the transformer, and near the K2, but there was no effect. I opened up the bottom of the K2 and noticed the greatest disturbance from the lamp transformer was around L31. That area also seemed to be the most sensitive to detuning when I put on and took off the cover (and my hand). So I put a few layers of the tape (insulated inside a poly) on top of L31 and there seemed to be a slight effect, but not enough to make me want to try to put it there. I may open the top and try L30. In better news, though, I found that moving the light from the left of the K2 to the right eliminated the modulation, at least on RX. Leigh. A Walker wrote: Hi Michael, Thanks for your comments. I think you are on to something. The only hope for lower magnetic field susceptibility for the K2 would be if either the VFO circuit were changed so as not to use an inductor for adjusting the quiescent resonance point of the VFO, or good magnetic shielding were used. One possibility would be to use a gapped pot core with slug tuning for L30, but it might be difficult to get sufficient adjustment range. Or, perhaps one could use some kind of shield for L30 alone. The standard sort of thing for low-level or precise RF circuits is to enclose them all in steel shielding, with steel partitions between circuit sections or stages (it's called egg crating). It's something Elecraft could keep in mind for a K3. If I had a K2 in front of me, I think I would try to put some kind of shielding around L30. Here is the web site of one vendor of shielding materials: http://www.lessemf.com/mag-shld.html By the way, I would guess that the Q of that Toko T1005 coil is determined by not only DC resistive loss in the wire, but also skin effect loss and core loss (and circulating currents from distributed capacitance, etc., etc.). I suppose we will never know for sure, as RF work at some point gets very empirical -- we just have to try it out, and if it works we're on to solving the next problem. Best of luck, 73, Allen Walker From: Masleid, Michael A. [EMAIL PROTECTED] To: A Walker [EMAIL PROTECTED] CC: Elecraft@mailman.qth.net Subject: RE: [Elecraft] Hum Coupling Date: Wed, 03 Nov 2004 13:01:47 -0600 Hello Allen, My guess is that magnetic fields from power transformers are either 1) being picked up by L30, or 2) that the magnetic fields are going through the cores of L30 and/or T5, and modulating the effective permeabilities of these cores. This will cause a modulation of inductance, and thus a modulation of the VFO frequency. The magnetic field is picked up by L30. To work best, the magnetic shield should completely surround the susceptible parts. Putting the shield on only one side seems to make things worse. Here's a possibility for experimenting with K2 susceptibility: Try using one of those bulk tape erasers near it. They put out huge 60Hz fields. [Just don't get it near your credit/bank cards!] Of course, keep it away from the latching relays. I used a tape head demagnetizer. Placing the probe near the base of L30 causes a vast huge amount of FM. Don't try this unless you cut the current way down. Looking on the scope, FM modulation is at 60 Hz, not 120 Hz, so we're not modulating the permeability, we seem to be inducing a 60 Hz voltage onto L30/T5 which is modulating the varacters. What I don't understand is this: I figure L30 has perhaps 14 turns, and 2.3 ohms winding resistance. I figure that the effective aperture is 1 cm squared. I figure that the winding resistance of T5 is 0.05 ohms, so a 1 gauss vertical 60 Hz field will induce 37 micro volts on T5. That should cause 0.3 Hz FM modulation on 80 meters. No one should notice that? BTW, I calculated 2.3 ohms from the Q, sensitivity at T5 goes way up if L30 has less resistance. I know that the cup and core used in L30 will focus any external field through the winding, but I don't know how to calculate how much. It would be nice if someone could put an L30 (TOKO T1005Z 4.7 uH) into a Helholtz coil and get the numbers on it (uV/gauss at 60Hz, winding resistance). 73, Michael __ ___ 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] Hum Coupling
Thanks! The foil is supposed to have be very good for magnetic shielding and so I thought I would try it, as it is small and light enough that it could be put inaide the rig if it works. I will report when I try it on L30. Leigh. On Mon, 3 Jan 2005 6:53 pm, Stuart Rohre wrote: Leigh, most of your coupling may be magnetic, if shielding did not reduce the RFI. You might want to experiment with steel shim stock or even tinplate from cans. The easiest fix is distance: Moving the rig away from magnetic and electric field sources of transformers as you have found. GL, Stuart K5KVH ___ 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] Hum Coupling
Leigh, most of your coupling may be magnetic, if shielding did not reduce the RFI. You might want to experiment with steel shim stock or even tinplate from cans. The easiest fix is distance: Moving the rig away from magnetic and electric field sources of transformers as you have found. GL, Stuart K5KVH
RE: [Elecraft] Hum Coupling
Hello Allen, My guess is that magnetic fields from power transformers are either 1) being picked up by L30, or 2) that the magnetic fields are going through the cores of L30 and/or T5, and modulating the effective permeabilities of these cores. This will cause a modulation of inductance, and thus a modulation of the VFO frequency. The magnetic field is picked up by L30. To work best, the magnetic shield should completely surround the susceptible parts. Putting the shield on only one side seems to make things worse. Here's a possibility for experimenting with K2 susceptibility: Try using one of those bulk tape erasers near it. They put out huge 60Hz fields. [Just don't get it near your credit/bank cards!] Of course, keep it away from the latching relays. I used a tape head demagnetizer. Placing the probe near the base of L30 causes a vast huge amount of FM. Don't try this unless you cut the current way down. Looking on the scope, FM modulation is at 60 Hz, not 120 Hz, so we're not modulating the permeability, we seem to be inducing a 60 Hz voltage onto L30/T5 which is modulating the varacters. What I don't understand is this: I figure L30 has perhaps 14 turns, and 2.3 ohms winding resistance. I figure that the effective aperture is 1 cm squared. I figure that the winding resistance of T5 is 0.05 ohms, so a 1 gauss vertical 60 Hz field will induce 37 micro volts on T5. That should cause 0.3 Hz FM modulation on 80 meters. No one should notice that? BTW, I calculated 2.3 ohms from the Q, sensitivity at T5 goes way up if L30 has less resistance. I know that the cup and core used in L30 will focus any external field through the winding, but I don't know how to calculate how much. It would be nice if someone could put an L30 (TOKO T1005Z 4.7 uH) into a Helholtz coil and get the numbers on it (uV/gauss at 60Hz, winding resistance). 73, Michael ___ 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] Hum Coupling
Hi Michael, Thanks for your comments. I think you are on to something. The only hope for lower magnetic field susceptibility for the K2 would be if either the VFO circuit were changed so as not to use an inductor for adjusting the quiescent resonance point of the VFO, or good magnetic shielding were used. One possibility would be to use a gapped pot core with slug tuning for L30, but it might be difficult to get sufficient adjustment range. Or, perhaps one could use some kind of shield for L30 alone. The standard sort of thing for low-level or precise RF circuits is to enclose them all in steel shielding, with steel partitions between circuit sections or stages (it's called egg crating). It's something Elecraft could keep in mind for a K3. If I had a K2 in front of me, I think I would try to put some kind of shielding around L30. Here is the web site of one vendor of shielding materials: http://www.lessemf.com/mag-shld.html By the way, I would guess that the Q of that Toko T1005 coil is determined by not only DC resistive loss in the wire, but also skin effect loss and core loss (and circulating currents from distributed capacitance, etc., etc.). I suppose we will never know for sure, as RF work at some point gets very empirical -- we just have to try it out, and if it works we're on to solving the next problem. Best of luck, 73, Allen Walker From: Masleid, Michael A. [EMAIL PROTECTED] To: A Walker [EMAIL PROTECTED] CC: Elecraft@mailman.qth.net Subject: RE: [Elecraft] Hum Coupling Date: Wed, 03 Nov 2004 13:01:47 -0600 Hello Allen, My guess is that magnetic fields from power transformers are either 1) being picked up by L30, or 2) that the magnetic fields are going through the cores of L30 and/or T5, and modulating the effective permeabilities of these cores. This will cause a modulation of inductance, and thus a modulation of the VFO frequency. The magnetic field is picked up by L30. To work best, the magnetic shield should completely surround the susceptible parts. Putting the shield on only one side seems to make things worse. Here's a possibility for experimenting with K2 susceptibility: Try using one of those bulk tape erasers near it. They put out huge 60Hz fields. [Just don't get it near your credit/bank cards!] Of course, keep it away from the latching relays. I used a tape head demagnetizer. Placing the probe near the base of L30 causes a vast huge amount of FM. Don't try this unless you cut the current way down. Looking on the scope, FM modulation is at 60 Hz, not 120 Hz, so we're not modulating the permeability, we seem to be inducing a 60 Hz voltage onto L30/T5 which is modulating the varacters. What I don't understand is this: I figure L30 has perhaps 14 turns, and 2.3 ohms winding resistance. I figure that the effective aperture is 1 cm squared. I figure that the winding resistance of T5 is 0.05 ohms, so a 1 gauss vertical 60 Hz field will induce 37 micro volts on T5. That should cause 0.3 Hz FM modulation on 80 meters. No one should notice that? BTW, I calculated 2.3 ohms from the Q, sensitivity at T5 goes way up if L30 has less resistance. I know that the cup and core used in L30 will focus any external field through the winding, but I don't know how to calculate how much. It would be nice if someone could put an L30 (TOKO T1005Z 4.7 uH) into a Helholtz coil and get the numbers on it (uV/gauss at 60Hz, winding resistance). 73, Michael _ Check out Election 2004 for up-to-date election news, plus voter tools and more! http://special.msn.com/msn/election2004.armx ___ 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] Hum Coupling
In a message dated 11/1/04 8:36:41 PM Eastern Standard Time, [EMAIL PROTECTED] writes: I cannot help but note that the venerable Kenwood TS-930S and TS-940S rigs had their big hunk of a power transformer mounted right next to the PLL section - and no hum problems were apparent, and it was NOT a toroidal type transformer, just a standard E+I section type, with no outer cover - you could see the laminations and windings. Yes, the PLL assemblies were inside shielded compartments, but there did not appear to be anything special about them - specifically, they were not Mu Metal, although they were steel. There's the answer. Steel is ferromagnetic, aluminum isn't. Steel isn't as good a shield as MuMetal, but it does the job. I suspect that a K2 built with a steel cabinet would be much more magnetic-field immune than the stock aluminum case. It would also weigh a lot more, but that may not be a problem for home use. However, the radio would operate just fine when the shield covers were open - as during testing and alignment, so the shielding or lack thereof (in the Kenwoods) was not germane to that sort of problem. Was the entire shield removed, or just the covers? I suspect a lot of the shield wss still in place. What was different about their design that made it hum proof - at least from fields induced by the mains transformer? The steel shield is a big factor. Another is that they may not have used iron-core coils in the PLL, or used a different type of iron. Yet another is the frequency range of the PLL. The prime suspect, IMHO, in the K2 hum pickup is the PLL coils with their iron cores. 73 de Jim, N2EY ___ 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] Hum Coupling
Fraser Robertson wrote: Interesting - I had complaint on air recently of having a wide CW carrier when using a tube linear about two feet from the K2/100. I do NOT have the problem (and I've had people listen carefully for it) with an Alpha 86 at full power located 4 feet from the K2. For what it's worth the front panel of the Alpha is perpendicular to the front panel of the K2. The Alpha has an enormous Hypersil transformer, as Earl mentions. I did have the problem with my HAM/2 antenna rotor control box closer than about two feet from the K2. -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco ___ 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] Hum Coupling
Fraser, G4BJM wrote: Interesting - I had complaint on air recently of having a wide CW carrier when using a tube linear about two feet from the K2/100. == Exactly the problem. Rather than hum, it sounds like noise on the sidebands of the signal -- becoming less broad as the distance between the K2 and the amp increases. This is easily heard when you monitor your transmitted signal on another receiver. The K2/100 is absolutely clean barefoot. Perhaps the field from a hypersil xfmr is greater than a normal xfmr. Both Alphas I have tested my K2 on, at home and at a friend's QTH) have hypersil HV xfmrs. I even removed the KPA100 and ran my 10-watt K2 into the amp with the same noisy sidebands occurring on its CW and SSB output. There IS a problem! 73, de Earl, K6SE ___ 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] Hum Coupling
Thanks for the mu metal info, Stuart. If Eric and Wayne don't come out with a mod for it, I'll try that. 73, de Earl, K6SE ___ 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] Hum Coupling
This belongs in the For What Its Worth file: I cannot help but note that the venerable Kenwood TS-930S and TS-940S rigs had their big hunk of a power transformer mounted right next to the PLL section - and no hum problems were apparent, and it was NOT a toroidal type transformer, just a standard E+I section type, with no outer cover - you could see the laminations and windings. Yes, the PLL assemblies were inside shielded compartments, but there did not appear to be anything special about them - specifically, they were not Mu Metal, although they were steel. However, the radio would operate just fine when the shield covers were open - as during testing and alignment, so the shielding or lack thereof (in the Kenwoods) was not germane to that sort of problem. What was different about their design that made it hum proof - at least from fields induced by the mains transformer? So, maybe the problem could be worth another look, as in maybe there is another way to solve it? Could something be done to the K2 itself to make it immune to this problem? This needs someone who is a better engineer than me to come up with an answer- I am just a lowly self-taught fumbler. 73, - Jim, KL7CC Michael Harris wrote: G'day, By coincidence I opened up our stereo amp to have a go at lubricating a noisy volume pot. I noticed that the torroidal mains transformer was of shielded construction. Maybe this is the answer to the PSU hum coupling problem. A 20A psu in a double height EC, speaker etc as has already been suggested. Regards, Mike VP8NO ___ 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] Hum Coupling
Jim, KL7CC wrote: So, maybe the problem [hum getting into the K2's PLL] could be worth another look, as in maybe there is another way to solve it? Could something be done to the K2 itself to make it immune to this problem? == Hum coupling from the K2's power supply xfmr is not much of a problem because separation of a couple of feet eliminates it. Hum coupling from a linear amp's hypersil HV xfmr is another story, however. Six feet is not sufficient distance from my Alpha 76CA. Ditto when my K2 was tried more than six feet from my friend's Alpha 99. Thirty feet separation does clear up the problem, but that is unacceptable. I am a QRO operator who chases DX and works the contests, so I cannot use my K2 for this purpose because of the trashy signal it puts out when used with an amplifier. Elecraft is aware of the problem and was going to investigate further into it, but that was perhaps a year ago. They were going to look into the possibility of fabricating a mu metal shield, but I have heard nothing back from them since. If no fix becomes evident soon, I'm afraid my K2/100 will be up for sale. 73, de Earl, K6SE ___ 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] Hum coupling?
Hi The K2 is susceptible to hum pick up. You must keep all sources of AC magnetic fields at least 3 feet away from the K2 or the VFO will be modulated by the hum. This has been noted many times here on the reflector. Even a high intensity lamp too close to the K2 was a problem. Do not stack the K2 on top of a power supply or amplifier or anything with a large power transformer Don Brown KD5NDB - Original Message - From: Tom Althoffmailto:[EMAIL PROTECTED] To: Elecraft@mailman.qth.netmailto:Elecraft@mailman.qth.net Sent: Thursday, October 28, 2004 4:13 PM Subject: [Elecraft] Hum coupling? Ten-Tec recommended putting the matching speaker/power supply of my old Omni-V on the RIGHT hand side of the radio. The audio lines ran on the left side and the transformer in the supply caused hum on receive. I'm experiencing similar AC hum on the K2 audio. The K2 sits on top of my Titan II and when the HV is set to operate (kicking in the big HV xfmr directly under the K2) I get the hum. If I pick the K2 up and move it about 3 away from the Titan then all is well. Has anyone else experienced hum from nearby power transformers? I plan on using a 10Amp analog supply (not here yet) and anticipate I might have to keep it away from the K2. I suspect switching supplies do not cause the same effect. Tom K2TA Greenwood Lake, NY K2 #1117 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.netmailto: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/elecrafthttp://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htmhttp://mailman.qth.net/subscribershtm Elecraft web page: http://www.elecraft.comhttp://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] Hum coupling? - A real fix!
At 10/29/2004 10:16 AM, Tom Hammond wrote: Supplies with big trnasformers, or even small ones carrying high current, can/will often cause hum on the K2. Best to space them a distance away. Switchers probably won't induce hum, but might cause in-band birdies by virtue of their switching frequency and (for some) lack of adequate filtering. 73, Tom HammondN0SS OK here's the new program! Supplies with real transformers can cause hum in the K2 Supplies with switching can cause birdies in the K2 What's the option? No power supply? No power supply, No hum, No birdies, No problem? Well, the sensitivity goes to Hell in a handbasket. The solution? The new K2-PSQ and K2-PSH K2-PSQ is a 4 amp power supply to power your K2 with a bit of current to spare. K2-PSH is a 25 amp power supply to power your K2/100 with a bit of current to spare. Both power supplies fit in an enclosure that fits right under your K2 or K2/100. How do they do it? SMT - the new technology. Brought to you by the Godzilla PoWer company, Surface Mount Transformers that can deliver up to 1 watts of live of power. In conjunction with Elecraft LLC, and QRP-L, Godzilla has miniaturized their line of very high power supplies to fit into the Elecraft KAT-100 1.5 enclosure with 99.89776% regulation (mandated by qrp-l, and several 6's). Just send the name of your financial institution and a letter from them with a line of unlimited credit to . well, you get the picture! Ok . wife brought the little white pills to calm me down and said she will let me go back to the shack for some 40M cw in a short while. They tell me I haven't been the same since Godzilla came out with the 3 db per hundred feet gain special coax. Guess I never should have ordered that 1000 feet spool! 73Hank dam, it's great to be retired and have time to sit back over a coffee and think . and think .. and think! */ INCLUDE DISCLAIMER Please hold off with your orders until you see the major announcement on these new products in approximately 150 days or 21 weeks. ___ 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] Hum coupling? - A real fix!
Actually - after toasting my internal KBT2 by overcharging with an uncontrolled solar panel (hint hint... words for the wise) - I bought a $50 MityMite 12Ah battery/charger from Autozone. I plug it in to charge when I'm not on the air, and then I unplug the charging cord, and turn on the radio and have RFI free operation (well - at least free of Power Supply related RFI). I think Elecraft might do well do design a matching UPS/PS for the K2 K2/100. It could utilize a smaller - well designed power supply that acts primarily as a charger for an internal 25+ Ah battery that is used to power the K2. It could go into an EC2 enclosure - and possibly have a forward facing speaker and digital readout of battery voltage readout and/or charger battery status LEDs (rapid charge, float charge, low-voltage disconnect). Another option might be a connection in the back for a solar panel or other 'high voltage DC' input (high voltage being 15-24V). - Daniel AA0NI --- Hank Kohl K8DD [EMAIL PROTECTED] wrote: OK here's the new program! Supplies with real transformers can cause hum in the K2 Supplies with switching can cause birdies in the K2 What's the option? No power supply? No power supply, No hum, No birdies, No problem? Well, the sensitivity goes to Hell in a handbasket. The solution? The new K2-PSQ and K2-PSH ___ 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] Hum coupling?
The bottom line on placement of rigs to avoid hum for Elecraft, or any other brand, is to place the transformers and switchers as far from the rigs as possible within reason. Use twisted pair leads from DC supplies external to the rigs, and shield them if possible. Alternatively (and at great cost) one could buy MuMetal to line a power supply cabinet on the side toward the rig, but then you have a massive metal piece blocking venting and cooling of the power supply. As BPL trials have shown us, Power sources are sources of noise. Rigs need low noise to have best sensitivity on receivers to work the DX. DX means distance so keep those supplies at DX. 73 Stuart K5KVH ___ 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] Hum coupling?
Actually, Tom switching supplies may have a worse coupling effect since they have an oscillator going at higher frequency than the power line, in addition to power line 60 Hz. And, even coupling of RF between Tuner and Radio can happen. At a Field Day one time, a tuner was placed on a Yaesu transceiver, and did not tune a dipole well at all. After some frustration, we discovered there was magnetic coupling right thru the aluminum case of the tuner from its coil to the radio's tuned circuits causing an RF feedback. Moving the tuner from the top of the radio cured all problems. -Stuart K5KVH ___ 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] Hum coupling?
I have an Astron 20 amp for my K2/100 and it sits on a stool UNDER the operating table. That keeps the table clear for other things and keeps the AC magnetic field out of the K2. I've also got an Astron 20 amp supply that lives under the desk. You forgot to mention that it also makes a nice foot warmer on cold days! ;-) -- 73, Brian VE7NGR ___ 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
