k2 audio power
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All,
I am just returning from a mountaintop weekend running the June QSO party in a multi-op environment. The k2 I supplied for the 222 station worked great, but there were several complaints, and I will be attempting to fix these before it's next excursion into this environment. The main complaint from all operators was audio power. There are 2 stations in the truck, and it is noisy with all of the amplifier fans and other local qrm. The volume knob on the k2 was never set below 3/4 to full for the entire weekend. When we used a second op for logging and "Y'ed" the headphones it was definitely at full throttle. I will at least add an external audio amp, but an internal mod would be good because I think it would be usefull even at home. There were other complaints too, but minor in nature. Manual PTT for cw being one of the other problems. With all of the external sequencing required for transverters and preamps and power amps, it would really be nice if the k2 would switch to tx when I pounce on the footswitch in cw. Other than that we pulled out the weak ones! Also, the agc off function was used well to make a couple of meteor contacts on 222. Lots of nice pings overnight. Ed wa3drc _______________________________________________ Elecraft mailing list Post to: [hidden email] http://mailman.qth.net/mailman/listinfo/elecraft You must subscribe to post. Subscriber Info (Addr. Change, Unsub etc): http://mailman.qth.net/subscribers.htm Elecraft page: http://www.elecraft.com |
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Ed and all,
Audio - I do use an external audio amplifier with the K2. CW PTT input - I am in the final stages of testing a mod to provide PTT in CW mode. It involves removing RF Board R1 and R2 and inserting a logic AND at that point. The only inconvience (which is not likely to be resolved soon) is that the same PTT input input used for CW will not function on SSB without manually changing an added switch. The normal mic jack PTT still work as it does now, and SSB VOX is not changed. If you would like to experiment with me, send me a note and I will scan the sheet with the schematic and instructions and send it to you. It will find its way to my website in due time. 73, Don W3FPR Life is what happens when you are making other plans ----- Original Message ----- > > I will at least add an external audio amp, but an internal mod would be good because I think it would be usefull even at home. > > There were other complaints too, but minor in nature. Manual PTT for cw being one of the other problems. With all of the external sequencing required for transverters and preamps and power amps, it would really be nice if the k2 would switch to tx when I pounce on the footswitch in cw. > > Other than that we pulled out the weak ones! Also, the agc off function was used well to make a couple of meteor contacts on 222. Lots of nice pings overnight. > > Ed wa3drc > _______________________________________________ Elecraft mailing list Post to: [hidden email] http://mailman.qth.net/mailman/listinfo/elecraft You must subscribe to post. Subscriber Info (Addr. Change, Unsub etc): http://mailman.qth.net/subscribers.htm Elecraft page: http://www.elecraft.com |
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In reply to this post by Ed Finn
Ed:
I used two K2's at W3CCX over the weekend. I found one of them to be usable under the multimulti conditions. That was not mine, but one built by John Sortor, KB3XG. He had mounted an auxiliary audio amplifier in the lid and it made a world of difference. We did over a million points for the first time in Packrats history. I will be adding external amplifiers to the ones I will be using for FD (2 transmitter, K2 QRP with AB2KT, W2GD, N2NT, N2NC, W2RQ, and other FRC'ers that show up) because it is simply a requirement for this kind of noisy environment. Bob N4HY > Ed and all, > > Audio - I do use an external audio amplifier with the K2. > > CW PTT input - I am in the final stages of testing a mod to provide PTT in > CW mode. It involves removing RF Board R1 and R2 and inserting a logic AND > at that point. > > The only inconvience (which is not likely to be resolved soon) is that the > same PTT input input used for CW will not function on SSB without manually > changing an added switch. The normal mic jack PTT still work as it does > now, and SSB VOX is not changed. > > If you would like to experiment with me, send me a note and I will scan the > sheet with the schematic and instructions and send it to you. It will find > its way to my website in due time. > > 73, > Don W3FPR > > Life is what happens when you are making other plans > ----- Original Message ----- > > > > > I will at least add an external audio amp, but an internal mod would be > good because I think it would be usefull even at home. > > > > There were other complaints too, but minor in nature. Manual PTT for cw > being one of the other problems. With all of the external sequencing > required for transverters and preamps and power amps, it would really be > nice if the k2 would switch to tx when I pounce on the footswitch in cw. > > > > Other than that we pulled out the weak ones! Also, the agc off function > was used well to make a couple of meteor contacts on 222. Lots of nice > pings overnight. > > > > Ed wa3drc > > > > > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > http://mailman.qth.net/mailman/listinfo/elecraft > You must subscribe to post. > Subscriber Info (Addr. Change, Unsub etc): > http://mailman.qth.net/subscribers.htm > Elecraft page: http://www.elecraft.com Elecraft mailing list Post to: [hidden email] http://mailman.qth.net/mailman/listinfo/elecraft You must subscribe to post. Subscriber Info (Addr. Change, Unsub etc): http://mailman.qth.net/subscribers.htm Elecraft page: http://www.elecraft.com |
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In reply to this post by Ed Finn
On Mon, 2004-06-14 at 14:20, [hidden email] wrote:
> The main complaint from all operators was audio power. There are 2 > stations in the truck, and it is noisy with all of the amplifier fans > and other local qrm. The volume knob on the k2 was never set below 3/4 > to full for the entire weekend. When we used a second op for logging > and "Y'ed" the headphones it was definitely at full throttle. I have seen this a few times now and I wonder what serial number your rig is? There is a mod to increase the audio power in the archives. Personally, #4044 has more than enough audio and I have never had it more than about half way up, even when operating outside! If it gets noisy I use a headset (Heil) and I am fine. Is it just my rig then or does the audio vary so much? Ian -- Ian Maude G0VGS Morecambe Lancs UK | [hidden email] Sysop of GB7MBC, the Morecambe Bay Cluster Running Linux and DXSpider : K2 #4044 Find out about Summits on the Air! Visit the SOTA web site at http://www.sota.org.uk _______________________________________________ Elecraft mailing list Post to: [hidden email] http://mailman.qth.net/mailman/listinfo/elecraft You must subscribe to post. Subscriber Info (Addr. Change, Unsub etc): http://mailman.qth.net/subscribers.htm Elecraft page: http://www.elecraft.com |
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In reply to this post by Ed Finn
On Mon, 14 Jun 2004 9:20:37 -0400, [hidden email] wrote:
>When we used a second op for logging and "Y'ed" the headphones it was definitely at full throttle. The audio system in a K2 is entirely adequate for serious contesting. I suspect you have made a poor choice of headphones. I own several good pairs of headphones, and all produce plenty of level when used with the K2. What you are looking for is a good combination of relatively high voltage sensitivity and moderate load impedance (100-250 ohms). It also helps if both sets of headphones are similar in this regard. The K2 headphone output has resistors in series to limit the output level. If you hang a low impedance load on it, you lose a lot of level. Many cheap consumer headphones are on the order of 8-20 ohms, and that is most likely your problem. The headphones I own and have used with the K2 are: Etymotic Research ER4S and ER4P -- these are tiny in-ear earphones, super for lightweight portable operation, and have the additional advantage of excellent isolation from outside noise. The ER4S's are 100 ohms, 108 dBSPL for 1 volt input; the ER4P's are 27 ohms, 108 dBSPL for 0.25 volts. These are precision professional units and aren't cheap, but the company makes a lower cost version (about $100 list) that should be fine for ham radio. Shure also makes a product like this for the in-ear monitors that they sell to musicians. Sony MDR-7506 and MDR-V6 -- these are standard, large, closed headphones with nice soft cushions, work for for long operating sessions. These sell in the $100 range. Sony, being Sony, doesn't put impedance and sensitivity specs on the data sheets that I have, but I suspect they are in the same range as the ER4S's. Technics RP-HT220 -- similar to the Sony units, not as nice, no longer made. All combinations of two pairs of these headphones are plenty loud enough when both are plugged into the K2 at the same time. AKG and Sennheiser also make good headphones of this type. When translating sensitivity specs, remember that dB is 20 log (V2/V1) and 10 log (P2/P1). So the ER4S and ER4P have the same power sensitivity. Jim Brown K9YC Audio Systems Group, Inc. Chicago http://audiosystemsgroup.com _______________________________________________ Elecraft mailing list Post to: [hidden email] http://mailman.qth.net/mailman/listinfo/elecraft You must subscribe to post. Subscriber Info (Addr. Change, Unsub etc): http://mailman.qth.net/subscribers.htm Elecraft page: http://www.elecraft.com |
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My Sony MDR 7506's have a DC resistance of 72 ohms per side. Since the
phones are in parallel, the rig will see about 36 ohms. I am not sure how that relates to impedance but it seems in the ballpark. Heating and reactance would increase it some but I don't know by how much. They are comfortable and very sensitive. I bought them because of good reviews on eham. 73 - Rick - K7MW > > Sony MDR-7506 and MDR-V6 -- these are standard, large, closed headphones with > nice soft cushions, work for for long operating sessions. These sell in the > $100 range. Sony, being Sony, doesn't put impedance and sensitivity specs on > the data sheets that I have, but I suspect they are in the same range as the > ER4S's. > _______________________________________________ Elecraft mailing list Post to: [hidden email] http://mailman.qth.net/mailman/listinfo/elecraft You must subscribe to post. Subscriber Info (Addr. Change, Unsub etc): http://mailman.qth.net/subscribers.htm Elecraft page: http://www.elecraft.com |
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You are confusing DC resistance with impedance. The impedance of a transducer
(loudspeaker, microphone, headphones) is a combination of the dc resistance of the voice coil, the motional impedances, and a resistance that corresponds to the power converted to sound. Thus, those headphones that look like 72 ohms to you DC ohm meter look more like 150-250 ohms to an audio frequency source. An antenna acts the same. If you were to measure the DC resistance of the wire that makes up your antenna, you might see an ohm or two, yet the impedance of the antenna may be anywhere from 10-20 ohms for a short mobile antenna to 40 ohms for a quarter wave vertical to 70 ohms for a dipole to hundreds of ohms for a longer antenna. Much of the difference is the radiation resistance, which is a circuit element that accounts for the power that is radiated. And, in both the antenna and the loudspeaker/headphones, there are reactances (L and C) that account for the resonances. In the loudspeaker/headphones they are mechanical resonances, where in the antenna they are electrical ones. Jim K9YC On Tue, 15 Jun 2004 21:32:40 -0700, Rick Dettinger wrote: >My Sony MDR 7506's have a DC resistance of 72 ohms per side. Since the >phones are in parallel, the rig will see about 36 ohms. _______________________________________________ Elecraft mailing list Post to: [hidden email] http://mailman.qth.net/mailman/listinfo/elecraft You must subscribe to post. Subscriber Info (Addr. Change, Unsub etc): http://mailman.qth.net/subscribers.htm Elecraft page: http://www.elecraft.com |
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