I recall reversing the phase of one head phone, with respect to the other, in a high-impedance head-set of 1960s' vintage. I incorporated a switch into the wiring to achieve apparent CW signal separation under some conditions.
It worked surprisingly well. I have tried the same thing with more modern phones but with less effect. If I find another pair of S G Brown type F phones or similar, I will do it again. 73 George, G4TPV -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: 28 May 2010 17:00 To: [email protected] Subject: Elecraft Digest, Vol 73, Issue 37 Send Elecraft mailing list submissions to [email protected] To subscribe or unsubscribe via the World Wide Web, visit http://mailman.qth.net/mailman/listinfo/elecraft or, via email, send a message with subject or body 'help' to [email protected] You can reach the person managing the list at [email protected] When replying, please edit your Subject line so it is more specific than "Re: Contents of Elecraft digest..." Today's Topics: 1. K3 Headphones (Doug Turnbull) 2. Re: ELECRAFT TO TOKYO HY-POWER 2.5 (Phil & Debbie Salas) 3. Re: K3 Was - Which headphones for stereo cw work? Now - Audio Spread Spectrum (Jim Campbell) ---------------------------------------------------------------------- Message: 1 Date: Fri, 28 May 2010 16:32:40 +0100 From: "Doug Turnbull" <[email protected]> Subject: [Elecraft] K3 Headphones To: <[email protected]> Message-ID: <6f2aa728e5e14cb797e91389a0f63...@doug1> Content-Type: text/plain; charset="us-ascii" Sam, When this topic was previously discussed I saw mention of Extreme Isolation EX 29 headphones which provide: 1) Good noise suppression (29 dB or nearly a factor of 1000 at 1000 Hz) so you can keep the volume down and not hear your station's fans or the TV in the next room. 2) Comfort and an adjustable padded headband. 3) Exact impedance match for the K3 at 32 Ohms and hence plenty of volume from the K3. 4) They are California made and cost $99. 5) Stereo headphones with built in adapter for the larger phone plug jack used on the K3 front panel. The adapter plugs in and then screws home over the smaller stereo plug attached permanently to the phones. The plugs appear to have gold plating, which is a complete waste. 6) They come with a nine foot line cord which I just wrapped around a toroidal core even though I was not experiencing problems with noise. They are also available with a 40 inch long cord. I purchased a set and am most pleased with them. You can look the Extreme Isolation EX-29 Headphones up on Google or go to http://www.quietheadphones.com/product/ex-29 and order by post for $99. These headphones are made for musicians to use in groups but I think they are missing another market. I also have the Heil Proset Plus but prefer these cans for CW work. Both sets of phones have their advantages but for CW the Extreme Isolation phones are more to my liking. The EX 29 will be clamped to my ears this weekend for CQ WPX. 73 Doug EI2CN PS EI5DI wrote an article for the NCJ some time back on the subject of headphones. He prefers Sony MDR EX71SL ear buds because cans bother his ears when he is wearing glasses. I also wear spectacles but mine have a thin wire frames and are comfortable with headphones. ------------------------------ Message: 2 Date: Fri, 28 May 2010 10:55:54 -0500 From: "Phil & Debbie Salas" <[email protected]> Subject: Re: [Elecraft] ELECRAFT TO TOKYO HY-POWER 2.5 To: <[email protected]> Message-ID: <8c53b5b469444ec6b441d24d018cc...@ownerpc> Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original The THP2.5 uses a regular 15-pin D-connector, whereas the K3 uses the 15-pin HD D-connector. Nothing special needs to be done, other than finding the pin outs from the manuals. The THP 2.5 even has pull-up resistors so early K3 radios will drive the band data input just fine (NOT the case with the THP 1.5, where you need the K3 pull-up mod). If you plan on using ALC, you do need the K3 negative-going ALC mod if you have an early K3. Phil - AD5X ------------------------------ Message: 3 Date: Fri, 28 May 2010 11:50:03 -0400 From: Jim Campbell <[email protected]> Subject: Re: [Elecraft] K3 Was - Which headphones for stereo cw work? Now - Audio Spread Spectrum To: "elecr...@elecraft List" <[email protected]> Message-ID: <[email protected]> Content-Type: text/plain; charset=ISO-8859-1; format=flowed This thread reminded me of something that I read back in I believe the '80s. There was a circuit in which the CW audio was spread spatially, i.e., the lower frequencies were heard toward your left side while the higher frequencies were heard toward the right. The idea was that the brain could do a good job of separating closely-spaced CW signals if they apparently came from different directions. This would require stereo headphones to implement. With the advent of DSP this might be a mode that Lyle could implement in the K3 if there was enough interest and if there was really an advantage in this mode. 72, Jim Campbell - W4BQP ------------------------------ _______________________________________________ Elecraft mailing list Post to: [email protected] http://mailman.qth.net/mailman/listinfo/elecraft You must be a subscriber to post. Elecraft web page: http://www.elecraft.com End of Elecraft Digest, Vol 73, Issue 37 **************************************** This mail has originated outside your organization, either from an external partner or the Global Internet. Keep this in mind if you answer this message. This e-mail and any attachment may contain confidential and/or privileged information. If you have received this e-mail and/or attachment in error, please notify the sender immediately and delete the e-mail and any attachment from your system. 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