Re: [Elecraft] RF Ammeter
Thanks to all who responded. Several circuits to try, so I am sure one of them will work for what I have in mind. Again, thank you. -- Jim, KL7CC __ 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] RF Ammeter
Rick Bates wrote: >A short Google search found: > >http://www.ifwtech.co.uk/g3sek/clamp-on/clamp-on.htm > >Merry/Happy Christmas, > >Rick WA6NHC > >-Original Message- >From: elecraft-boun...@mailman.qth.net >[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Doug Faunt N6TQS >+1-510-655-8604 >Sent: Sunday, December 18, 2011 12:54 PM >To: elecraft@mailman.qth.net >Subject: Re: [Elecraft] RF Ammeter > >I couldn't locate the GM3SEK article (is it still there?), but this is >also useful: >http://www.w8ji.com/building_a_current_meter.htm > >And I believe that QST and/or the ARRL Handbook has information on this, >also. > >73, doug You're there ahead of me. The typical clamp-on RF current meter with a 10-turn secondary and a 50-ohm terminating resistance has a theoretical insertion resistance of 0.5 ohms, so it doesn't disturb the antenna very much. In practice the resistance is increased by the gaps in the core, so if possible I'd suggest threading the antenna wire through a ferrite toroid instead (probably #43 material for general HF use - NOT iron dust). The article by G0SNO on the page referenced above shows how the RF current meter can be quite accurately calibrated using a transmitter, wattmeter and dummy load. -- 73 from Ian GM3SEK http://www.ifwtech.co.uk/g3sek __ 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] RF Ammeter
Jim, I sent you direct the construction info on my 0-100 mA and 0-1.5A RF ammeter that includes photos and schematic. I hope your e-mail system allows the attachments. If not, let me know. This is an in-line ammeter, not a clamp on type. Ron AC7AC -Original Message- 7 As everyone knows, "real" RF ammeters are becoming scarce, or very expensive. Does anyone out there have info on where to find a circuit that is relatively inexpensive that I could use as a substitute? Something using a toroid core plus diode, or something like that, would be what I am looking for. Not too complicated in any case, and absolute accuracy is not needed - a relative indication would be fine. The application is measuring RF current for a trailing wire antenna from an airplane.Transmitter power is in the 100 watt range. Thank in advance - Jim, KL7CC __ 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] RF Ammeter
A short Google search found: http://www.ifwtech.co.uk/g3sek/clamp-on/clamp-on.htm Merry/Happy Christmas, Rick WA6NHC -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Doug Faunt N6TQS +1-510-655-8604 Sent: Sunday, December 18, 2011 12:54 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] RF Ammeter I couldn't locate the GM3SEK article (is it still there?), but this is also useful: http://www.w8ji.com/building_a_current_meter.htm And I believe that QST and/or the ARRL Handbook has information on this, also. 73, doug __ 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] RF Ammeter
I couldn't locate the GM3SEK article (is it still there?), but this is also useful: http://www.w8ji.com/building_a_current_meter.htm And I believe that QST and/or the ARRL Handbook has information on this, also. 73, doug On 18-Dec-11 19:17, Jim Wiley wrote: > > As everyone knows, "real" RF ammeters are becoming scarce, or very > expensive. Does anyone out there have info on where to find a circuit > that is relatively inexpensive that I could use as a substitute? > Something using a toroid core plus diode, or something like that, would > be what I am looking for. Not too complicated in any case, and > absolute accuracy is not needed - a relative indication would be fine. > The application is measuring RF current for a trailing wire antenna > from an airplane.Transmitter power is in the 100 watt range. > > > Thank in advance > > > - Jim, KL7CC > > > __ > 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] RF Ammeter
On 12/18/2011 11:17 AM, Jim Wiley wrote: > Does anyone out there have info on where to find a circuit > that is relatively inexpensive that I could use as a substitute? > Something using a toroid core plus diode, or something like that, would > be what I am looking for. Yep. Google to find GM3SEK's excellent website. 73, JimK9YC __ 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] RF Ammeter
On 12/18/2011 11:17 AM, Jim Wiley wrote: > As everyone knows, "real" RF ammeters are becoming scarce, or > very expensive. Does anyone out there have info on where to find > a circuit that is relatively inexpensive that I could use as a > substitute? Something using a toroid core plus diode, or > something like that, would be what I am looking for. RF ammeters - direct reading or remote reading - are used extensively in AM broadcast antenna arrays. In most cases they are available off-the-shelf but cheap they are not. I'm sorry that I don't have a convenient URL to point you to but check the sites of AM BC transmission equipment suppliers. -- 73 de K2ASP - Phil Kane Elecraft K2/100 s/n 5402 __ 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] RF Ammeter
As everyone knows, "real" RF ammeters are becoming scarce, or very expensive. Does anyone out there have info on where to find a circuit that is relatively inexpensive that I could use as a substitute? Something using a toroid core plus diode, or something like that, would be what I am looking for. Not too complicated in any case, and absolute accuracy is not needed - a relative indication would be fine. The application is measuring RF current for a trailing wire antenna from an airplane.Transmitter power is in the 100 watt range. Thank in advance - Jim, KL7CC __ 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
