Re: [AMRadio] Modulator question.
Greetings from a lurker -- Dick has an interesting idea here and I enjoy pretending that I know how to play the numbers so here goes... Let's use the 200w figure with a car amp with a bridge amplifier powered by the car's 12v battery, and for the moment we will neglect the losses. The amp's output transistors will produce a maximum output voltage swing of 6v peak (12 v peak to peak.) With a sine wave, the rms voltage will be about 0.707 x 6vpk = 4.24vrms. The AC rms current at the 200w output level will be about 200w/4.24v = 47.2 amps to drive an impedance of 4.24v/47.2a = 0.0898 ohms. So now all we need is a couple or three big honkin' car batteries, several feet of car battery/starter-motor cable,a 200w rms car amp that is actually capable of 200w (which will be much larger than what most manufacturers CALL a "200w" amp), and a 200w modulation transformer with a primary impedance of 0.0898 ohms. Oh, and don't forget what Larry said about DC current through the secondary of the transformer... and we still haven't figured-in the losses. So, is it doable? How much money do you have Dick? The guys have presented some good options, that are most definately doable. But if your heart is set on ss high-level modulation, there might be a better way to go... Here is an amp that uses +65v/-65v for power instead of +12v/0v: http://www.apexjr.com/Cerwinfullrange.htm With this amp, the max sinewave output voltage is 65v peak, or .707*65vpk = 46vrms. For 200w output the rms current will be 200w/46v = 4.35arms to drive a load of 46v/4.35a = 10.6 ohms. When you figure in the losses, the load will probably need to be closer to 8 ohms -- just perfect for that off-the-shelf 200w audio output transformer. In reality, I suspect the transformer will be a problem -- but not an impossibility. I think it's worth a shot Dick! Al disclaimer: I have no connection with apexjr.com other than being a satisfied customer. Dick wrote: >I have over the years built several low power AM transmitters. I would like >to build something a little bigger say in the 400-500 watt plate modulated. >I have been kicking around the idea of using one of the solid state >amplifiers made for car audio driving a reverse connected audio >transformer. I have seen these audio output transformers available in the >200 watt range. I understand that the RF output stage would have to be >designed to fit the impedence of the output transformer. Does this sound >like it could be done? > > K6KWQ Dick > Amps by "MORE POWER" __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [AMRadio] Modulator question.
RICHARD GEORGE wrote: > I have over the years built several low power AM transmitters. I would like > to build something a little bigger say in the 400-500 watt plate modulated. > I have been kicking around the idea of using one of the solid state > amplifiers made for car audio driving a reverse connected audio transformer. > I have seen these audio output transformers available in the 200 watt range. > I understand that the RF output stage would have to be designed to fit the > impedence of the output transformer. Does this sound like it could be done? > Well, sort of... The problem will be if you run the RF PA plate supply current through the modulation transformer (or modulation transformer wannabe) secondary. The transformer then needs to be designed for an unbalanced DC current flowing through one of the windings, because the core is magnetized by this current, leaving less effective core for the audio signal riding on top of it. Don't know of the output transformers you are talking about are single-ended (unlikely at 200W) or push-pull. If single-ended, you can run a DC current through the winding to the extent it was designed for. If PP, then no, you can't, you can have a modulation choke pass the DC current to the RF PA, and capacitively (AC) couple the transformer secondary to the choke (Heising system). But then, you need to find a suitable modulation choke, which could be as difficult as finding a suitable modulation transformer. Chokes and transformers designed for an unbalanced DC current have all the E and I leaves lined up, and have a precise air gap separating the two stacks. Transformers designed for no DC current, or DC currents that cancel as in a PP winding, have the E and I sections interleaved. 73, -Larry/NE1S __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [AMRadio] Modulator question.
Talk with Jim (WD5JKO), I think he has used a Crown P.A. amplifier as a cathode modulator, maybe an SB-200 as the final? Unless you're stuck with 13.8 VDC, I would look for something in the commercial P.A. type amps.(Guitar Center,Musician's Friend, pawn shops,etc.) I have a 45 year old Fender PA-100 with 4 6L6's in Push-Pull, that is being converted into a modulator for a pair of 807's, the RF deck and power supply are done. Have Fun AD5HR, Jon --- On Fri, 5/7/10, Ron.K3PID wrote: > From: Ron.K3PID > Subject: Re: [AMRadio] Modulator question. > To: "Discussion of AM Radio in the Amateur Service" > Date: Friday, May 7, 2010, 6:53 PM > Don't you just hate it when someone > replies to your post with a different > question and a dozen people try to answer his question but > nobody answers > yours? I'm sorry I can't help you out Dick, but I > thought I would > acknowledge your initial question. > > 73 > K3PID - Ron H. > > > __ > Our Main Website: http://www.amfone.net > AMRadio mailing list > Searchable Archives: http://www.mail-archive.com/[email protected]/ > List Rules (must read!): http://w5ami.net/amradiofaq.html > List Home: http://mailman.qth.net/mailman/listinfo/amradio > Post: [email protected] > To unsubscribe, send an email to [email protected] > with > the word unsubscribe in the message body. > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [AMRadio] Modulator question.
Don't you just hate it when someone replies to your post with a different question and a dozen people try to answer his question but nobody answers yours? I'm sorry I can't help you out Dick, but I thought I would acknowledge your initial question. 73 K3PID - Ron H. __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [AMRadio] Modulator question.
Several members of the Gulf Coast Mullet Society Net on 3885 kcs use the combination of a DX-60 driving a Heath SB-200 and their audio sounds great, along with some RF punch to boot. 73 Robert W4RL Trustee of W4GCM - Original Message - From: "Bob Macklin" To: "Discussion of AM Radio in the Amateur Service" Sent: Friday, May 07, 2010 5:33 PM Subject: Re: [AMRadio] Modulator question. >A transmitter like the DX-60 puts out about 12W of carrier in AM mode. It > uses Controlled Carrier modulation and does not require a modulation > transformer. > > Bob Macklin > K5MYJ > Seattle, Wa. > "Real Radios Glow In The Dark" > - Original Message - > From: "MUCHSTUFF" > To: "Discussion of AM Radio in the Amateur Service" > > Sent: Friday, May 07, 2010 3:05 PM > Subject: Re: [AMRadio] Modulator question. > > >> Have you considered using a car audio amplifier in a cathode modulation? >> If possible it could avoid finding another transformer that would stand >> the >> higher voltage and current in a plate arrangement. >> I give this some thought every time I'm in my friends car audio store. >> But, being one who always starts too much new stuff, I stop thinking >> about >> it. >> >> Gene, WB6SZS >> >> >> >> - Original Message - >> From: "RICHARD GEORGE" >> To: "amlist" >> Sent: Friday, May 07, 2010 12:34 PM >> Subject: [AMRadio] Modulator question. >> >> >>>I have over the years built several low power AM transmitters. I would >>>like >>>to build something a little bigger say in the 400-500 watt plate >>>modulated. >>>I have been kicking around the idea of using one of the solid state >>>amplifiers made for car audio driving a reverse connected audio >>>transformer. I have seen these audio output transformers available in the >>>200 watt range. I understand that the RF output stage would have to be >>>designed to fit the impedence of the output transformer. Does this sound >>>like it could be done? >>> >>> K6KWQ Dick >>> Amps by "MORE POWER" >>> __ >>> Our Main Website: http://www.amfone.net >>> AMRadio mailing list >>> Searchable Archives: >>> http://www.mail-archive.com/[email protected]/ >>> List Rules (must read!): http://w5ami.net/amradiofaq.html >>> List Home: http://mailman.qth.net/mailman/listinfo/amradio >>> Post: [email protected] >>> To unsubscribe, send an email to [email protected] with >>> the word unsubscribe in the message body. >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >> >> __ >> Our Main Website: http://www.amfone.net >> AMRadio mailing list >> Searchable Archives: http://www.mail-archive.com/[email protected]/ >> List Rules (must read!): http://w5ami.net/amradiofaq.html >> List Home: http://mailman.qth.net/mailman/listinfo/amradio >> Post: [email protected] >> To unsubscribe, send an email to [email protected] with >> the word unsubscribe in the message body. >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> > > __ > Our Main Website: http://www.amfone.net > AMRadio mailing list > Searchable Archives: http://www.mail-archive.com/[email protected]/ > List Rules (must read!): http://w5ami.net/amradiofaq.html > List Home: http://mailman.qth.net/mailman/listinfo/amradio > Post: [email protected] > To unsubscribe, send an email to [email protected] with > the word unsubscribe in the message body. > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [AMRadio] Modulator question.
A transmitter like the DX-60 puts out about 12W of carrier in AM mode. It uses Controlled Carrier modulation and does not require a modulation transformer. Bob Macklin K5MYJ Seattle, Wa. "Real Radios Glow In The Dark" - Original Message - From: "MUCHSTUFF" To: "Discussion of AM Radio in the Amateur Service" Sent: Friday, May 07, 2010 3:05 PM Subject: Re: [AMRadio] Modulator question. > Have you considered using a car audio amplifier in a cathode modulation? > If possible it could avoid finding another transformer that would stand > the > higher voltage and current in a plate arrangement. > I give this some thought every time I'm in my friends car audio store. > But, being one who always starts too much new stuff, I stop thinking about > it. > > Gene, WB6SZS > > > > - Original Message - > From: "RICHARD GEORGE" > To: "amlist" > Sent: Friday, May 07, 2010 12:34 PM > Subject: [AMRadio] Modulator question. > > >>I have over the years built several low power AM transmitters. I would >>like >>to build something a little bigger say in the 400-500 watt plate >>modulated. >>I have been kicking around the idea of using one of the solid state >>amplifiers made for car audio driving a reverse connected audio >>transformer. I have seen these audio output transformers available in the >>200 watt range. I understand that the RF output stage would have to be >>designed to fit the impedence of the output transformer. Does this sound >>like it could be done? >> >> K6KWQ Dick >> Amps by "MORE POWER" >> __ >> Our Main Website: http://www.amfone.net >> AMRadio mailing list >> Searchable Archives: http://www.mail-archive.com/[email protected]/ >> List Rules (must read!): http://w5ami.net/amradiofaq.html >> List Home: http://mailman.qth.net/mailman/listinfo/amradio >> Post: [email protected] >> To unsubscribe, send an email to [email protected] with >> the word unsubscribe in the message body. >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html > > __ > Our Main Website: http://www.amfone.net > AMRadio mailing list > Searchable Archives: http://www.mail-archive.com/[email protected]/ > List Rules (must read!): http://w5ami.net/amradiofaq.html > List Home: http://mailman.qth.net/mailman/listinfo/amradio > Post: [email protected] > To unsubscribe, send an email to [email protected] with > the word unsubscribe in the message body. > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [AMRadio] Modulator question.
Have you considered using a car audio amplifier in a cathode modulation? If possible it could avoid finding another transformer that would stand the higher voltage and current in a plate arrangement. I give this some thought every time I'm in my friends car audio store. But, being one who always starts too much new stuff, I stop thinking about it. Gene, WB6SZS - Original Message - From: "RICHARD GEORGE" To: "amlist" Sent: Friday, May 07, 2010 12:34 PM Subject: [AMRadio] Modulator question. >I have over the years built several low power AM transmitters. I would like >to build something a little bigger say in the 400-500 watt plate modulated. >I have been kicking around the idea of using one of the solid state >amplifiers made for car audio driving a reverse connected audio >transformer. I have seen these audio output transformers available in the >200 watt range. I understand that the RF output stage would have to be >designed to fit the impedence of the output transformer. Does this sound >like it could be done? > > K6KWQ Dick > Amps by "MORE POWER" > __ > Our Main Website: http://www.amfone.net > AMRadio mailing list > Searchable Archives: http://www.mail-archive.com/[email protected]/ > List Rules (must read!): http://w5ami.net/amradiofaq.html > List Home: http://mailman.qth.net/mailman/listinfo/amradio > Post: [email protected] > To unsubscribe, send an email to [email protected] with > the word unsubscribe in the message body. > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [AMRadio] Modulator question.
Hi Brian, Do you have a modulation scheme in mind? i.e., high-level, plate or controlled carrier or others While "rolling your own" can be done and certainly is rewarding when the whole magilla finally works...there might be other avenues to explore. For example, there are rigs like the Eico 720 when coupled to the Eico 730 modulator gives a pretty nice low-power signal. Back issues of Electric Radio have one or two articles addressing this lashup. The fairly common Heath DX-60 family of AM/CW transmitters provides a good base for some nice AM signals when used with an ordinary linear amplifier. Done up right, they sound might impressive. Again, some nice Electric Radio articles address the finer points. But there are also opportunities for "low-power" AM rigs to be found in older ARRL handbooks and Bill Orr's publications over the years. Pick your tube, design the power supply and the rest is relatively simple. Just thinking out loud with you. Others may have more/better ideas. But accomplishing what you desire is not that difficult. Let us hear back from you. May be able to steer a particular design your way. 73 Chuck W4MIL -Original Message- From: Brian Zwiener To: Discussion of AM Radio in the Amateur Service Sent: Fri, May 7, 2010 4:49 pm Subject: Re: [AMRadio] Modulator question. Speaking of AM Transmitters, does anyone have a source for plans to build an AM ransmitter for 75 meters in the 15-25 watt range?Thanks. Brian/KF5CCN --- On Fri, 5/7/10, RICHARD GEORGE wrote: From: RICHARD GEORGE ubject: [AMRadio] Modulator question. o: "amlist" ate: Friday, May 7, 2010, 2:34 PM I have over the years built several low power AM transmitters. I would like o build something a little bigger say in the 400-500 watt plate modulated. have been kicking around the idea of using one of the solid state mplifiers made for car audio driving a reverse connected audio transformer. have seen these audio output transformers available in the 200 watt range. understand that the RF output stage would have to be designed to fit the mpedence of the output transformer. Does this sound like it could be done? K6KWQ Dick Amps by "MORE POWER" __ ur Main Website: http://www.amfone.net MRadio mailing list earchable Archives: http://www.mail-archive.com/[email protected]/ ist Rules (must read!): http://w5ami.net/amradiofaq.html ist Home: http://mailman.qth.net/mailman/listinfo/amradio ost: [email protected] o unsubscribe, send an email to [email protected] with he word unsubscribe in the message body. This list hosted by: http://www.qsl.net lease help support this email list: http://www.qsl.net/donate.html _ ur Main Website: http://www.amfone.net MRadio mailing list earchable Archives: http://www.mail-archive.com/[email protected]/ ist Rules (must read!): http://w5ami.net/amradiofaq.html ist Home: http://mailman.qth.net/mailman/listinfo/amradio ost: [email protected] o unsubscribe, send an email to [email protected] with he word unsubscribe in the message body. This list hosted by: http://www.qsl.net lease help support this email list: http://www.qsl.net/donate.html __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [AMRadio] Modulator question.
Brian, My friend Steve, GW1XVC, has one of the best QRZ websites for AM radio constructors that I know of, take a look and build yourself a nice radio, all of the parts are available new so nothing impossible there, 73 Max M0GHQ/W8BX - Original Message - From: "Brian Zwiener" To: "Discussion of AM Radio in the Amateur Service" Sent: Friday, May 07, 2010 9:49 PM Subject: Re: [AMRadio] Modulator question. Speaking of AM Transmitters, does anyone have a source for plans to build an AM Transmitter for 75 meters in the 15-25 watt range?Thanks. - Brian/KF5CCN -- I am using the free version of SPAMfighter. We are a community of 7 million users fighting spam. SPAMfighter has removed 2815 of my spam emails to date. Get the free SPAMfighter here: http://www.spamfighter.com/len The Professional version does not have this message __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [AMRadio] Modulator question.
On 5/7/2010 4:49 PM, Brian Zwiener wrote: > Speaking of AM Transmitters, does anyone have a source for plans to build an > AM Transmitter for 75 meters in the 15-25 watt range? Do a search on Radio Animal's "Grenade" Transmitter. He uses them on his Pirate Shortwave Station WKND "K-9 Dog Radio". You can find plans for copy cat transmitters online. While the originals were made for 41 Meters, they are easy to tune to 75 Meters. -- 73, Kevin Raper KJ4HYD CE WCKI WQIZ There is no limitation to the fidelity of AM radio. From a mathematical standpoint, AM does better in frequency response than FM. - Leonard Kahn __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [AMRadio] Modulator question.
Speaking of AM Transmitters, does anyone have a source for plans to build an AM Transmitter for 75 meters in the 15-25 watt range?Thanks. - Brian/KF5CCN --- On Fri, 5/7/10, RICHARD GEORGE wrote: From: RICHARD GEORGE Subject: [AMRadio] Modulator question. To: "amlist" Date: Friday, May 7, 2010, 2:34 PM I have over the years built several low power AM transmitters. I would like to build something a little bigger say in the 400-500 watt plate modulated. I have been kicking around the idea of using one of the solid state amplifiers made for car audio driving a reverse connected audio transformer. I have seen these audio output transformers available in the 200 watt range. I understand that the RF output stage would have to be designed to fit the impedence of the output transformer. Does this sound like it could be done? K6KWQ Dick Amps by "MORE POWER" __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
