[Elecraft] K2 - Isolation box construction for digital modes
I'm building an isolation box (between K2 and computer with external soundcard) for digital operations, containing two 1:1 transformers and voltage divider resistors. The box is metal. All input and output sockets are 3.5mm mono and are grounded to the box, hence all input and output braids are connected together via the box. Is this likely to create a ground loop problem? Advice would be appreciated before I solder it all together. 73, Euan M0GBZ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K2 - Isolation box construction for digital modes
If you do that, you can leave out the isolation transformers - and the whole box for that matter. You're un-isolating them by connecting the grounds together. Bob W5OV -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Euan McPherson Sent: Monday, February 22, 2010 5:32 AM To: elecraft@mailman.qth.net Subject: [Elecraft] K2 - Isolation box construction for digital modes I'm building an isolation box (between K2 and computer with external soundcard) for digital operations, containing two 1:1 transformers and voltage divider resistors. The box is metal. All input and output sockets are 3.5mm mono and are grounded to the box, hence all input and output braids are connected together via the box. Is this likely to create a ground loop problem? Advice would be appreciated before I solder it all together. 73, Euan M0GBZ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K2 - Isolation box construction for digital modes
Euan, Your grounds should not be connected between the K2 and the computer - that will un-isolate your isolation box. At the isolation box, use stereo plugs and jacks at your interface box and connect the transformers to the tip and ring. Similar if you are using an opto-isolator on the PTT circuit - use a stereo jack and plug there too. If you wish to use shielded cables between the box and the K2, ground the shield only at the K2 end (use 2 conductor plus shield cable). Actually twisted pair conductors will be as good or better than shielded cable - CAT-5 wires are good for self shielding. 73, Don W3FPR Euan McPherson wrote: I'm building an isolation box (between K2 and computer with external soundcard) for digital operations, containing two 1:1 transformers and voltage divider resistors. The box is metal. All input and output sockets are 3.5mm mono and are grounded to the box, hence all input and output braids are connected together via the box. Is this likely to create a ground loop problem? Advice would be appreciated before I solder it all together. 73, Euan M0GBZ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K2 - Isolation box construction for digital
My instincts would agree with Bob on this question. You might consider using stereo jacks with (Ring Tip) only wired and use the GND as sheilding. Or you could omit the connector and wire direct out with a rubber grommet in the box wholes. N1BBR --- If you do that, you can leave out the isolation transformers - and the whole box for that matter. You're un-isolating them by connecting the grounds together. Bob W5OV -- bw...@fastmail.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K2 - Isolation box construction for digital
I would buy a) isolated jacks, b) mount regular jacks in plastic to isolate them, or c) use an all plastic box to isolate them. That was you don't have to remember to use a specially wired cable to preserve the isolation. Tim, N9PUZ On Monday, February 22, 2010 11:04 AM [GMT+1=CET], dw wrote: My instincts would agree with Bob on this question. You might consider using stereo jacks with (Ring Tip) only wired and use the GND as sheilding. Or you could omit the connector and wire direct out with a rubber grommet in the box wholes. N1BBR --- If you do that, you can leave out the isolation transformers - and the whole box for that matter. You're un-isolating them by connecting the grounds together. Bob W5OV __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K2 - Isolation box construction for digital modes
Hello Euan, When I built my interface box here (years before K3's were available - HI), I did have ground loop problems. I floated all the grounds in all the cables and did NOT connect them all together at the box. The only place they were grounded was at the mic connector on the radio. The way I did this was to use 1/8 stereo connectors in and out of the box, but to use the right and left terminals to transfer the lines into and out of the box, while leaving the ground unused. GL and VY 73, Lance On 2/22/2010 11:31 AM, Euan McPherson wrote: I'm building an isolation box (between K2 and computer with external soundcard) for digital operations, containing two 1:1 transformers and voltage divider resistors. The box is metal. All input and output sockets are 3.5mm mono and are grounded to the box, hence all input and output braids are connected together via the box. Is this likely to create a ground loop problem? Advice would be appreciated before I solder it all together. 73, Euan M0GBZ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html -- Lance Collister, W7GJ (ex: WN3GPL, WA3GPL, WA1JXN, WA1JXN/C6A, ZF2OC/ZF8, E51SIX) P.O. Box 73 Frenchtown, MT 59834 USA QTH: DN27UB TEL: (406) 626-5728 URL: http://www.bigskyspaces.com/w7gj LIVE MESSENGER CHAT: w...@hotmail.com 2m DXCC #11, 6m DXCC #815 Interested in 6m EME? Ask me about subscribing to the Magic Band EME email! __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K2 - Isolation box construction for digital
My metal isolation box shares ground with the computer. That way I can use normal audio jacks and cables. On the other side, I use a DB9 connector to isolate the box from any wires going to the radio. My PTT connection is isolated via an optoisolator (4N33), requiring another DB9 to the computer serial port for control. If you isolate the audio signals but not PTT, then you've again un-isolated everything. If you use VOX for PTT, this isn't an issue. 73's, John AA0VE Tim N9PUZ wrote: I would buy a) isolated jacks, b) mount regular jacks in plastic to isolate them, or c) use an all plastic box to isolate them. That was you don't have to remember to use a specially wired cable to preserve the isolation. Tim, N9PUZ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K2 - Isolation box construction for digital modes
You would be well advised to read Computer to Radio Interfacing - You Don't Need An Expensive Interface! http://www.audiosystemsgroup.com/HamInterfacing.pdf, by Jim Brown, a frequent contributor to this list and an expert on interference to audio systems. Basically, throw away the transformers and provide very good functional earth bonding between all the components. Euan McPherson wrote: I'm building an isolation box (between K2 and computer with external soundcard) for digital operations, containing two 1:1 transformers and voltage divider resistors. The box is metal. All input and output sockets are 3.5mm mono and are grounded to the box, hence all input and output braids are connected together via the box. Is this likely to create a ground loop problem? Advice would be appreciated before I solder it all together. -- David Woolley we do not overly restrict the subject matter on the list, and we encourage postings on a wide range of amateur radio related topics List Guidelines http://www.elecraft.com/elecraft_list_guidelines.htm __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
