Re: [Elecraft] K3 AM TX - Questions and Observations
Yes I'm also hoping/waiting for AM TX to be allowed on an FM filter. I've yet to try it but I'm sure if I lie to the K3 it'll work... As to how clean and w/in spec it'll be that would take some looking... ~BTH On Tue, 2010-05-11 at 07:19 -0600, Duncan Carter wrote: > Using the FM filter for AM transmit has been requested but may or may > not happen. According to Wayne, this depends on whether it can meet > transmit specs and development priorities. I'd like to have AM mainly > to work one friend who is running 1950s Harvey Wells gear but all the > filter slots in my K3 are filled already. The FM filter does work fine > for receiving AM, at least for KCFR, one of my wife's favorite public > radio stations. > > Dunc, W5DC > __ > 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] K3 AM TX - Questions and Observations
Gee, that is a nice "toy" Mark. I wonder how many K3's you could buy for the price of one of those units Andy VK4KY -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-AM-TX-Questions-and-Observations-tp5033894p5039455.html Sent from the [K3] mailing list archive at Nabble.com. __ 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] K3 AM TX - Questions and Observations
In AM analog broadcast, asymmetrical modulation is standard fare. http://www.vorsis.com/pdfnfoto/Vorsis%20AM10%20InkJet%20090722.pdf Output specs on page 7. 73 de na6m On 5/11/2010 10:08 PM, Andy Wood wrote: > > Hi Joe, > > Yes, you are correct and I understand what you are saying. > > However, reduced carrier power from the K3 TX is not an issue if driving an > external amplifier to, say, 100 watts carrier. In this case, output from the > K3 may be only 10 watts carrier (40w peak), leaving plenty of overhead to > accommodate an increase in positive modulation well beyond 100%. > > Andy VK4KY __ 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] K3 AM TX - Questions and Observations
Hi Joe, Yes, you are correct and I understand what you are saying. However, reduced carrier power from the K3 TX is not an issue if driving an external amplifier to, say, 100 watts carrier. In this case, output from the K3 may be only 10 watts carrier (40w peak), leaving plenty of overhead to accommodate an increase in positive modulation well beyond 100%. Andy VK4KY -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-AM-TX-Questions-and-Observations-tp5033894p5039377.html Sent from the [K3] mailing list archive at Nabble.com. __ 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] K3 AM TX - Questions and Observations
Andy, > This is probably the reason it currently cannot be modulated > in excess of 100% positive. Maybe there will be an update in > the future? You do not want more than 100% positive modulation with the K3. If one assumes 25W of carrier, 100% positive modulation represents 100W peak power ... modulation greater than 100% positive would result in limiting/compression in the final amplifier with its attendant distortion. To obtain greater than 100% positive modulation (particularly in a low level modulation with linear amplifier situation), the final amplifier must be capable of PEP greater than four times the carrier power. The only way the K3 could support more than 100% positive modulation is if the carrier power were reduced and that would be rather self defeating. 73, ... Joe, W4TV On 5/11/2010 9:27 PM, Andy Wood wrote: > > Thanks for the reply Tom - your information is appreciated. I have been to > your website a few times but I hadn't visited the AM page before. Lots of > good information there. I had to read it a few times to take it all in. > > I have done some more research and it appears the K3 TX has a quite > sophisticated, multiple loop ALC system. This is probably the reason it > currently cannot be modulated in excess of 100% positive. Maybe there will > be an update in the future? > > Andy VK4KY > __ 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] K3 AM TX - Questions and Observations
Thanks for the reply Tom - your information is appreciated. I have been to your website a few times but I hadn't visited the AM page before. Lots of good information there. I had to read it a few times to take it all in. I have done some more research and it appears the K3 TX has a quite sophisticated, multiple loop ALC system. This is probably the reason it currently cannot be modulated in excess of 100% positive. Maybe there will be an update in the future? Andy VK4KY -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-AM-TX-Questions-and-Observations-tp5033894p5039154.html Sent from the [K3] mailing list archive at Nabble.com. __ 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] K3 AM TX - Questions and Observations
Using the FM filter for AM transmit has been requested but may or may not happen. According to Wayne, this depends on whether it can meet transmit specs and development priorities. I'd like to have AM mainly to work one friend who is running 1950s Harvey Wells gear but all the filter slots in my K3 are filled already. The FM filter does work fine for receiving AM, at least for KCFR, one of my wife's favorite public radio stations. Dunc, W5DC __ 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] K3 AM TX - Questions and Observations
I can't speak for details on the K3. Only generally. > I also have a question regarding asymetric AM modulation > and the K3 - is it > possible for the TX to exceed 100% positive modulation > whilst maintaining > less than 100% negative? Being only new to the AM mode, I > am not sure if it > is possible with any TX that uses low level modulation. > Any info greatly > appreciated. It is actually easier to have clean asymmetrical modulation with low-level AM than it is with a tetrode in a plate modulated circuit. It is also easier to have better linearity with low level modulation. http://www.w8ji.com/amplitude_modulation.htm Someday I'll have to get an AM filter and try my K3. I guess there is no way to use the transmitter without an AM filter 73 Tom __ 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
