Re: [AMRadio] Amplifier to use with my DX-60
In a message dated 3/18/06 8:48:57 PM, [EMAIL PROTECTED] writes: > I would be interested in that Dennis. > TNX. > Mod-U-Lator, > Mike(y) > W3SLK > Mike, Are you good in QRZ? Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Amplifier to use with my DX-60
In a message dated 3/19/06 10:01:34 AM, [EMAIL PROTECTED] writes: > I would appreciate a copy of this info. > > Healthfully yours, > DON W4BWS > Don, Are you good in QRZ? Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Amplifier to use with my DX-60
In a message dated 3/19/06 12:19:58 PM, [EMAIL PROTECTED] writes: > The 1956 QST gives you so much more for 25 cents > extra. You get vintage yellowed pages, a nest of > Silverfish, and Wayne Green's "Never Say Die" soap box > editorial... :-) > > Jim > > --- W5OMR/Geoff <[EMAIL PROTECTED]> wrote: > > > Jim Candela wrote: > > > > >Check out Ebay, a copy of CQ magazine, Article: > > June > > >1956, Mobile Reference-shift Modulator, Item > > number: > > >5834903572, cost $4.00 buy it now > > > > > > > back issues of ER are $3.75 > > > > > Just checked my CQ collection and discovered I have the June 56 issue. The "Mobile Reference Shift" article was written by Dale Hileman, K6DDV, the author of the earlier Radio and TV News piece. Both articles cover essentially the same ground. For those who requested more information on the scheme I will include a copy of the CQ article along with my later discussion as published in ER. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Amplifier to use with my DX-60
Geoff, The 1956 QST gives you so much more for 25 cents extra. You get vintage yellowed pages, a nest of Silverfish, and Wayne Green's "Never Say Die" soap box editorial... :-) Jim --- W5OMR/Geoff <[EMAIL PROTECTED]> wrote: > Jim Candela wrote: > > >Check out Ebay, a copy of CQ magazine, Article: > June > >1956, Mobile Reference-shift Modulator, Item > number: > >5834903572, cost $4.00 buy it now > > > > back issues of ER are $3.75 > > > > __ > AMRadio mailing list > Home: > http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami, Paul > Courson/wa3vjb >
RE: [AMRadio] Amplifier to use with my DX-60
From: Brett gazdzinski <[EMAIL PROTECTED]> I myself cant even think about operating without the mod monitor and pep reading watt meter, its like driving at night without headlights! Actually I find wattmeters pretty useless. I prefer a thermocouple rf ammeter to indicate maximum rf current while tuning up and to monitor for normal rf line current to the antenna. I also find meter type modulation monitors of limited use. But to me operating without a monitor scope is like driving with the headlights off. I use the envelope pattern most of the time. Don ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] Amplifier to use with my DX-60
I would appreciate a copy of this info. Healthfully yours, DON W4BWS - Original Message - From: <[EMAIL PROTECTED]> To: Sent: Saturday, March 18, 2006 10:07 PM Subject: Re: [AMRadio] Amplifier to use with my DX-60 For a simple and very effective modulator for rigs in this power class that doesn't require increasingly hard to find modulation iron, let me recommend a Heising circuit originally described in the April 1955 issue of Radio and Television News and revisited in ER #91, Nov. 1996. The scheme utilizes a clever bias shifting scheme to squeeze 30 - 40 watts of audio out of a single 807 modulator tube. No transformer required, only a 10 H filter choke. Won't modulate 100% in the negative direction (in common with other Heising circuits) but comes so close you can't tell the difference. The original author called it a "Reference Shift Modulator." Can provide more information if anyone's interested. Dennis D. W7QHO Glendale, CA __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
Re: [AMRadio] Amplifier to use with my DX-60
W5OMR/Geoff wrote: Jim Candela wrote: Check out Ebay, a copy of CQ magazine, Article: June 1956, Mobile Reference-shift Modulator, Item number: 5834903572, cost $4.00 buy it now back issues of ER are $3.75 and, that's FROM Electric Radio. -Geoff/W5OMR
Re: [AMRadio] Amplifier to use with my DX-60
Jim Candela wrote: Check out Ebay, a copy of CQ magazine, Article: June 1956, Mobile Reference-shift Modulator, Item number: 5834903572, cost $4.00 buy it now back issues of ER are $3.75
Re: [AMRadio] Amplifier to use with my DX-60
Check out Ebay, a copy of CQ magazine, Article: June 1956, Mobile Reference-shift Modulator, Item number: 5834903572, cost $4.00 buy it now --- W5OMR/Geoff <[EMAIL PROTECTED]> wrote: > Mike Sawyer wrote: > > >I would be interested in that Dennis. > > > > > >The original author called it a "Reference Shift > Modulator." Can provide > >more information if anyone's interested. > > > > ER had an article on it... > > Author: DuVall > Issue: 91 > Date: Nov-96 > Page: 8 > > If someone has this available in paste-able text, or > a website, I'd be > interested as well. > > > -- > 73 = Best Regards, > -Geoff/W5OMR > > > __ > AMRadio mailing list > Home: > http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami, Paul > Courson/wa3vjb >
Re: [AMRadio] Amplifier to use with my DX-60
Mike Sawyer wrote: I would be interested in that Dennis. The original author called it a "Reference Shift Modulator." Can provide more information if anyone's interested. ER had an article on it... Author: DuVall Issue: 91 Date: Nov-96 Page: 8 If someone has this available in paste-able text, or a website, I'd be interested as well. -- 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] Amplifier to use with my DX-60
I would be interested in that Dennis. TNX. Mod-U-Lator, Mike(y) W3SLK - Original Message - From: <[EMAIL PROTECTED]> To: Sent: Saturday, March 18, 2006 11:07 PM Subject: Re: [AMRadio] Amplifier to use with my DX-60 For a simple and very effective modulator for rigs in this power class that doesn't require increasingly hard to find modulation iron, let me recommend a Heising circuit originally described in the April 1955 issue of Radio and Television News and revisited in ER #91, Nov. 1996. The scheme utilizes a clever bias shifting scheme to squeeze 30 - 40 watts of audio out of a single 807 modulator tube. No transformer required, only a 10 H filter choke. Won't modulate 100% in the negative direction (in common with other Heising circuits) but comes so close you can't tell the difference. The original author called it a "Reference Shift Modulator." Can provide more information if anyone's interested. Dennis D. W7QHO Glendale, CA __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
Re: [AMRadio] Amplifier to use with my DX-60
For a simple and very effective modulator for rigs in this power class that doesn't require increasingly hard to find modulation iron, let me recommend a Heising circuit originally described in the April 1955 issue of Radio and Television News and revisited in ER #91, Nov. 1996. The scheme utilizes a clever bias shifting scheme to squeeze 30 - 40 watts of audio out of a single 807 modulator tube. No transformer required, only a 10 H filter choke. Won't modulate 100% in the negative direction (in common with other Heising circuits) but comes so close you can't tell the difference. The original author called it a "Reference Shift Modulator." Can provide more information if anyone's interested. Dennis D. W7QHO Glendale, CA
Fwd: [AMRadio] Amplifier to use with my DX-60
Re: [AMRadio] Amplifier to use with my DX-60
In a message dated 3/18/06 9:41:29 AM, [EMAIL PROTECTED] writes: > Actually, I'm a subscriber and have that issue. How did I miss > remembering that when I got the DX-60? > > Thanks, > > Harry, KT4AE > Maryville, Tennessee > > [EMAIL PROTECTED] wrote: > > Harry, > > In the January, 2004 issue of Electric Radio, there is an article on > > the DX-60... > Also, see ER# 133 (May 2000) and 140 (Jan. 2001) Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Amplifier to use with my DX-60
Harry, Can you send me a copy of that article. I have 2 DX60's and collect all the mod info I can find. Healthfully yours, DON W4BWS Don Sanders PO Box 10195 Dothan, AL 36304 [EMAIL PROTECTED] - Original Message - From: "Harry Vaught" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Cc: "Discussion of AM Radio" Sent: Saturday, March 18, 2006 11:40 AM Subject: Re: [AMRadio] Amplifier to use with my DX-60 > Actually, I'm a subscriber and have that issue. How did I miss > remembering that when I got the DX-60? > > Thanks, > > Harry, KT4AE > Maryville, Tennessee > > [EMAIL PROTECTED] wrote: > > Harry, > > In the January, 2004 issue of Electric Radio, there is an article on > > the DX-60... > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb >
Re: [AMRadio] Amplifier to use with my DX-60
Thanks Jim and to everyone who provided information. I actually asked more out of curiosity, since the subject had been raised, than as an actual likely project. Thanks again to everyone. Jim candela wrote: Harry, You will need to find a suitable modulation transformer...
RE: [AMRadio] Amplifier to use with my DX-60
Harry, You will need to find a suitable modulation transformer for the impedances, and power levels used. If the amp uses metal 6L6's, consider pathways towards a little higher power, as 25 watts is a little light for this job. I might be wrong but my recollection is that a 6146 is good for 65 watts DC input on AM. Backing that down to 50 watts DC input to better match your PA amp power is another option. You might be able to use another audio output transformer to raise the voice coil impedance back up, but if you do this look at a single ended transformer designed to handle DC current flow (these have gapped cores). There are some in the 25 watt category that audiophiles use, but don't expect a cheap price. Alternatively you could use another push pull output transformer, a choke, and an AC capacitor to shunt the 6146 plate current away from the non-gapped 2nd transformer. The use of back to back transformers is not usually the best choice, but with the limited availability of modulation transformers, the back to back transformer idea has a certain appeal to it. Once these details are worked out, you need to make a mod to disable the modulator when you are not transmitting. You might add a relay and hook that into the transmit PTT circuit. The details on how this goes will depend on the circuitry in your own equipment, and whatever choice you prefer. If you could post the schematic somewhere of that PA amp, maybe the group could offer suggestions on how to adapt it to modulator usage. Regards, Jim WD5JKO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Harry Vaught Sent: Friday, March 17, 2006 7:13 AM To: Discussion of AM Radio Subject: Re: [AMRadio] Amplifier to use with my DX-60 Ok, tell me this: I have a DX-60A and a 25 watt P-P 6L6 Webster Electric PA amp with a large selection of output impedances. What would I have to do to plate modulate my DX-60? There are obviously greatly varying levels of knowledge out there, and mine is probably below median. Harry, KT4AE Maryville, Tennessee __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 3/17/2006
Re: [AMRadio] Amplifier to use with my DX-60
Actually, I'm a subscriber and have that issue. How did I miss remembering that when I got the DX-60? Thanks, Harry, KT4AE Maryville, Tennessee [EMAIL PROTECTED] wrote: Harry, In the January, 2004 issue of Electric Radio, there is an article on the DX-60...
Re: [AMRadio] Amplifier to use with my DX-60
Harry, In the January, 2004 issue of Electric Radio, there is an article on the DX-60. There is a ckt for adding Heising modulation w/ a 6146 and a few parts. It looks easy and simple. Single issues of ER are available. Ya can order on line. The issue also has a brief history of AM modulation methods along with circuits. klc - Original Message - From: Harry Vaught <[EMAIL PROTECTED]> Date: Friday, March 17, 2006 2:56 pm Subject: Re: [AMRadio] Amplifier to use with my DX-60 Cc: 'Discussion of AM Radio' > Thanks to those who replied to my question about plate modulating > my > DX-60. Amazingly, the conversions sound practical. > > I was expecting posts which started, "First, obtain some > unobtainium...". > Thanks, guys. > > Harry, KT4AE > Maryville, Tennessee > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb >
Re: [AMRadio] Amplifier to use with my DX-60
Don K4KYV said: "I hear a lot of guys on the air with AM linears, and most of the time they claim to be running way too much carrier for the tubes they are using. I often hear stuff like 200 watts out with a pair of 811A's or 250 watts out with a pair of 813's in g-g. If so, they are cooking the tubes, or else the efficiency is running too high, and they are flat-topping all over the place." I agree with your comments and yes, there is no doubt that those rigs are flat-topping. I've been running linear amps on AM for years and I find that the cleanest, best sounding signal comes from a linear with LOTS OF PLATE DISSIPATION and HEADROOM. In addition, an audio signal generator and an oscilloscope are mandatory to get clean results. Not everyone has this equipment and it is a hobby after all so folks do the best they can. As a rule of thumb I consider the plate dissipation divided by 3 to be a general yardstick for AM linears, some tubes giving a little more and some a little less. In the case of a pair of 3-500Z's I rate them in the 333-350 watt carrier class. So while a pair of 813's can be a wonderful plate modulated rig, as an AM linear they are not worth all the trouble of building them. It seems to me to be a waste of time to build an AM linear with much less than 1000 watts of plate dissipation. Of course if you have a low power rice box and already own some kind of linear, well go ahead, but if one is building an AM linear, more dissipation is better. 73, Ken W2DTC
RE: [AMRadio] Amplifier to use with my DX-60
I agree with that, it seems to me, lately, MANY people on the air are generating a lot of splatter. Often, the received signal looks ok (sometimes not), the audio sounds very good, but tune off frequency and they are generating artifacts way out. I see other people overmodulating, others with under 50% mod, people 2 kc off frequency, etc. On 40 meters, we often ran 5 Kc spacing, groups on 7295, 7290, 7285, and I did not hear the other guys with a 5.5Kc filter. Now, I often hear the people on 7285 on 7295. A lot of the people have been around a long time, so I am not sure what is up, extreme hifi not doing well through the transmitter? I myself cant even think about operating without the mod monitor and pep reading watt meter, its like driving at night without headlights! Brett N2DTS > Unfortunately, very few hams use scopes as modulation > monitors anymore. > They have become so unpopular that the major transceiver > manufacturers no > longer include monitor scopes in their equipment line, and > haven't done so > for years. I suppose the new breed of ham finds oscilloscope > patterns too > complicated to understand. No wonder there are so many > trashy signals on > the air. > > Don K4KYV > >
Re: [AMRadio] Amplifier to use with my DX-60
My main concern Don is that giving out a calculated carrier level for a set of tubes to a guy who does not have a scope and audio generator is not going to give the amateur band another clean signal. As I mentioned in a previous email, I have been unable to obtain the efficiencies you mention and would like to hear from someone who can measure everything with test equipment and tell me about it. I have never worked much with AM linears or low level modulation in my own station, but I have helped others set up their amplifiers. I do recall getting a SB-220 working with a FT-301, running a KW DC input and about 350 watts carrier out, with good modulation on the scope and little downward carrier shift in modulation. I also recall a Continental Electronics 250 watt broadcast transmitter used as a stand-by at a station where I once worked, which used a pair of 4-250's in the final, running a combination of screen and control grid modulation. It ran 250 watts output, with full 100% modulation, and the DC input was exactly 750 watts input. I recall back in the 60's, Walt WB4AOE running a pair of 833A's in class B linear service and getting 350 watts carrier output, until he acquired a modulation transformer to run plate modulation with another pair. I hear a lot of guys on the air with AM linears, and most of the time they claim to be running way too much carrier for the tubes they are using. I often hear stuff like 200 watts out with a pair of 811A's or 250 watts out with a pair of 813's in g-g. If so, they are cooking the tubes, or else the efficiency is running too high, and they are flat-topping all over the place. To me, that's the disadvantage of low level AM. You have to fiddle with it and get everything just exactly right: not too much grid drive, make sure you have heavy enough antenna loading, and keep the audio level at the right place. With plate modulation, the antenna loading and rf drive are not critical. Just tune everything to resonance, and make sure you are not overmodulating (and that the modulator is putting out clean audio), and as long as the tube is running reasonably close to recommended parameters, everything will be ok. Unfortunately, very few hams use scopes as modulation monitors anymore. They have become so unpopular that the major transceiver manufacturers no longer include monitor scopes in their equipment line, and haven't done so for years. I suppose the new breed of ham finds oscilloscope patterns too complicated to understand. No wonder there are so many trashy signals on the air. Don K4KYV ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] Amplifier to use with my DX-60
If I use a modulator to do plate modulation with the DX-60 what considerations are there regarding connection the plate circuit in respects to RF shielding, etc from the modulator circuit? Tom K3TVC - Original Message - From: "Harry Vaught" <[EMAIL PROTECTED]> Cc: "'Discussion of AM Radio'" Sent: Friday, March 17, 2006 2:56 PM Subject: Re: [AMRadio] Amplifier to use with my DX-60 > Thanks to those who replied to my question about plate modulating my > DX-60. Amazingly, the conversions sound practical. > > I was expecting posts which started, "First, obtain some unobtainium...". > > Thanks, guys. > > Harry, KT4AE > Maryville, Tennessee > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb >
Re: [AMRadio] Amplifier to use with my DX-60
About $100 each new I believe My Centurion has 2 of them and they have lasted over 5 years now. 375 watts of carrier is easy on them. - Original Message - From: "John E. Coleman (ARS WA5BXO)" <[EMAIL PROTECTED]> To: "'Discussion of AM Radio'" Sent: Friday, March 17, 2006 10:28 AM Subject: RE: [AMRadio] Amplifier to use with my DX-60 Yep, there is no doubt that the pair of 3-500Zs and getting rid of the control carrier on the DX60 would be better but a lot more expense I think. Aren't 3-500Zs pretty expensive? John -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim candela Sent: Friday, March 17, 2006 10:00 AM To: Discussion of AM Radio Subject: RE: [AMRadio] Amplifier to use with my DX-60 John, Your approach as always is a good one, and can be made to work out quite well. This extra box will allow about a 6DB increase in power from what a screen modulated 6146 can do. The DX-60 with carrier control can arguably better match up to a linear amplifier, but must of us would agree that carrier control as done on this rig is too much, and annoying to those copying a weak signal that goes into and out of the noise with modulation peaks. Now consider these options: 1.) Modify the DX-60 for non carrier control screen modulation. That should provide about 20 watts carrier with room for + 100% modulation. 2.) Modify the DX-60 for plate modulation. This might require a 6146 bias change for proper class C plate modulation bias. You will also have to deal with modulating the screen grid. The plate tuning capacitor might flash over, and other components may need to be beefed up to handle the higher peak power. Once done, you will have a fine 45-50 watt AM rig that you could be proud of. 3.) Combine option 1 with this: Mate up the modified DX-60 to a linear with 1000 watts of dissipation available (like two 3-500Z's). Now you can easily run 250 watts AM or more (maybe 375) of quality AM. 4.) Use the DX-60 as is (stock), or with an amplifier as you wish. The choice is yours, Jim WD5JKO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of John E. Coleman (ARS WA5BXO) Sent: Thursday, March 16, 2006 9:10 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] Amplifier to use with my DX-60 I still say, forget the linear, and use less money to build a plate modulator for the DX60. It will work better, sound better, cost less, and heat the shack up less. As I recall the DX 60 has a 6146 in the final for class C CW and puts out about 40-50 watts of carrier if it were plate modulated it would do at least 200 watts PEP and sound great. There is a number of different ways to do the modulator. A lot of guys just find and old PA and a transformer to match to the final. Some build the modulator output stages only, input XFMR tubes and modulation XFMR. Then they drive it with a small microphone amp. That's more stuff to set around on the desk but it works. There are a lot of self contained 25 and 50 watt modulator circuits around and probably a lot of complete one piece store bought modulators as well. As I recall, EICO had a pretty nice one that was to go with the EICO model 720 but it was used on many different rigs as well as being used as a driver for big modulators. A buddy of mine had an ECIO 720 and built a nice home brewed modulator for it using 1625s in AB1. It sounded real good. I built one similar to it with less power output for my Knight Kit T60. The T60 had the same control carrier AM that the DX60 does. What a difference it made when it was plate modulated. Very little modification is necessary in the DX60 to accommodate the external modulator. John, WA5BXO __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006 __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] Amplifier to use with my DX-60
Jim, I suppose it is also preference. BJ and I modified the Kenwood TS820 to full double sideband and it runs about 10-20 watts carrier output in that mode we drive and SB200 modified with a switch to kick in extra bias when we use in on AM. It puts out about 75-80 watts carrier with good modulation characteristics. So the combo is equivalent to a DX100 with maybe better audio. John -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim candela Sent: Friday, March 17, 2006 1:48 PM To: Discussion of AM Radio Subject: RE: [AMRadio] Amplifier to use with my DX-60 John, Yep 3-500z's are expensive. That said, I've seen "working" Heath SB-220's for sale around $300.00. Also many of us in this group already have a nice linear already as part of their SSB station. If it is already there, use it on AM! Cheers, Jim
Re: [AMRadio] Amplifier to use with my DX-60
On Fri, 17 Mar 2006, Harry Vaught wrote: I was expecting posts which started, "First, obtain some unobtainium...". Then of course it would have been "Oh - that's on eBay right now, Item Number XX. RARE L@@K VINTAGE UNOBTANIUM Never Opened - With Hard-to-Find Original Label" Cheers John KB6SCO
Re: [AMRadio] Amplifier to use with my DX-60
Thanks to those who replied to my question about plate modulating my DX-60. Amazingly, the conversions sound practical. I was expecting posts which started, "First, obtain some unobtainium...". Thanks, guys. Harry, KT4AE Maryville, Tennessee
RE: [AMRadio] Amplifier to use with my DX-60
John, Yep 3-500z's are expensive. That said, I've seen "working" Heath SB-220's for sale around $300.00. Also many of us in this group already have a nice linear already as part of their SSB station. If it is already there, use it on AM! Cheers, Jim -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of John E. Coleman (ARS WA5BXO) Sent: Friday, March 17, 2006 10:29 AM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] Amplifier to use with my DX-60 Yep, there is no doubt that the pair of 3-500Zs and getting rid of the control carrier on the DX60 would be better but a lot more expense I think. Aren't 3-500Zs pretty expensive? John -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim candela Sent: Friday, March 17, 2006 10:00 AM To: Discussion of AM Radio Subject: RE: [AMRadio] Amplifier to use with my DX-60 John, Your approach as always is a good one, and can be made to work out quite well. This extra box will allow about a 6DB increase in power from what a screen modulated 6146 can do. The DX-60 with carrier control can arguably better match up to a linear amplifier, but must of us would agree that carrier control as done on this rig is too much, and annoying to those copying a weak signal that goes into and out of the noise with modulation peaks. Now consider these options: 1.) Modify the DX-60 for non carrier control screen modulation. That should provide about 20 watts carrier with room for + 100% modulation. 2.) Modify the DX-60 for plate modulation. This might require a 6146 bias change for proper class C plate modulation bias. You will also have to deal with modulating the screen grid. The plate tuning capacitor might flash over, and other components may need to be beefed up to handle the higher peak power. Once done, you will have a fine 45-50 watt AM rig that you could be proud of. 3.) Combine option 1 with this: Mate up the modified DX-60 to a linear with 1000 watts of dissipation available (like two 3-500Z's). Now you can easily run 250 watts AM or more (maybe 375) of quality AM. 4.) Use the DX-60 as is (stock), or with an amplifier as you wish. The choice is yours, Jim WD5JKO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of John E. Coleman (ARS WA5BXO) Sent: Thursday, March 16, 2006 9:10 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] Amplifier to use with my DX-60 I still say, forget the linear, and use less money to build a plate modulator for the DX60. It will work better, sound better, cost less, and heat the shack up less. As I recall the DX 60 has a 6146 in the final for class C CW and puts out about 40-50 watts of carrier if it were plate modulated it would do at least 200 watts PEP and sound great. There is a number of different ways to do the modulator. A lot of guys just find and old PA and a transformer to match to the final. Some build the modulator output stages only, input XFMR tubes and modulation XFMR. Then they drive it with a small microphone amp. That's more stuff to set around on the desk but it works. There are a lot of self contained 25 and 50 watt modulator circuits around and probably a lot of complete one piece store bought modulators as well. As I recall, EICO had a pretty nice one that was to go with the EICO model 720 but it was used on many different rigs as well as being used as a driver for big modulators. A buddy of mine had an ECIO 720 and built a nice home brewed modulator for it using 1625s in AB1. It sounded real good. I built one similar to it with less power output for my Knight Kit T60. The T60 had the same control carrier AM that the DX60 does. What a difference it made when it was plate modulated. Very little modification is necessary in the DX60 to accommodate the external modulator. John, WA5BXO __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006 __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb __ AMRadio mailing list Home: http://mailman.qth.net/mailman/l
RE: [AMRadio] Amplifier to use with my DX-60
Ken, The answer to your question is YES, But. The but comes from the fact that linear amplifiers need to be monitored with a scope looking for proper linearity, more so than plate modulation. I use the trapezoid pattern, and I always tune for max as you describe, and then when cutting back the drive to about 25%, I modulate while looking at the trapezoid. Almost always I have to adjust the linear loading control for a linear ramp as I approach 100% modulation. So with a linear you need the scope, and trapezoid pattern selection to get things correct, and then set the audio level. With plate modulation you only set the audio level. So what percentage of this group uses a scope on AM? So what percentage of the scope users utilize the Trapezoid pattern? Remember for the Trapezoid you use scope in X:Y mode where the audio at scope suitable level (about 10 volts peak) goes into the horizontal channel, and the RF into the vertical channel. Regards, Jim I have been called a square before, but never a trapezoid! -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of kenw2dtc Sent: Thursday, March 16, 2006 7:25 PM To: Discussion of AM Radio Subject: Re: [AMRadio] Amplifier to use with my DX-60 Jim, I guess my question is really: Can anyone actually demonstrate a real AM linear that can output 500 watts carrier and show 2000 watts PEP into a dummy load with a nice looking audio sine wave on the scope, from the RF pickup, while running 1500 watts DC input ? If so, please send me an email at [EMAIL PROTECTED] The reason I ask is: A. None of my amps has ever been that good and B. Unfortunately, a number of people running AM linears do not have scopes and if you tell them that a pair of whatever tubes can achieve a certain carrier power, they will put the carrier to that level via dipping and peaking the pi-net until their wattmeter reaches the specified power and talk. In my experience, by the time you heavily load the output to achieve the perfect audio sine wave, your tuning controls are quite different than what is was when you peaked everything and the efficiency is no longer as good as what the calculations show. On top of that most male voices have peaks that should have an additional de-rating of output power. So when someone asks about what kind of carrier power a certain pair of tubes can put out in AM linear service, I really like to give a conservative number, not the math numbers. 73, Ken W2DTC __ Ken Barber Middletown, NJ Radio Website: http://w2dtc.com Family Photos: http://kenw2dtc.home.comcast.net __ - Original Message - From: "Jim candela" <[EMAIL PROTECTED]> To: "Discussion of AM Radio" Sent: Thursday, March 16, 2006 7:22 PM Subject: RE: [AMRadio] Amplifier to use with my DX-60 > > Don, > > You said: "So you could run maximum 1500 watts DC input to those tubes, > with 500 watts > carrier output, and 1000 watts dissipated by the tubes". > > Reply from Jim WD5JKO: > > What is stated above is correct if the tubes can dissipate 1000 watts of > heat (like two 3-500Z's flat out blushing), and the drive is adjusted to > about 1/4th that for maximum PEP output. In this case the efficiency is > assummed to be about 33%, so 1500 X .333 = 500 watts. The efficiency may > vary some, and is usually lower then that, so the 33% assumption is only a > first guess. It could be 25%, and that really upsets the situation making > the linear more of a heater, and less of a transmitter. > > One good thing about the 1500 watt PEP output power rule we all complain > about is that efficiency doesn't matter as much now. You can legally run a > 15 KW PEP input amplifier with 10% efficiency to provide 1500 watts PEP > output. It wouldn't make a lot of sense, or be practical, but it's now > legal. Back in the 1000 watts DC input days things were a lot different, > and > the SB-220's input would likely exceed 1000 watts DC before the AM carrier > got to 375 like we often do today with these amps. The point here is that > for low efficiency linears, or grid modulated amplifiers, we can > sometimes > run more power today on AM then before the rules changed from 1000 watts > DC > input to 1500 watts PEP output. Of course this isn't the case with plate > modulation where an output PEP at or maybe more than 3KW PEP WAS possible, > and completely legal. > > Regards, > Jim > WD5JKO > > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf Of kenw2dtc > Sent: Thursday, March 16, 2006 4:21 PM > To: Discussion of AM Radio > Subject: Re: [AMRadio] Amplifier to use with my DX-60 > > > Don says: > > "So you could run maximum 1500 watts DC i
RE: [AMRadio] Amplifier to use with my DX-60
Well first of all Harry I am not familiar with the Webster Electric PA amp but 25 watts output is a little on the light side but is usable if you don't load the DX60 to more than 40-50 watts plate input power. You could probably use a 25 watt audio output XFMR rated of single ended use, so it would handle the DC from the final. I have used a 200 watt power XFMR from old television sets as a modulation XFMR. Use the HV Secondary as the final side (experiment as to whether using all of the secondary or one half) and input from the PA (16 ohm to 12V) or (500 ohm to 110V). Experimentation might be necessary. Basically, if the 6146 rig is 500V and 100ma it would require 25 watts at 353 V RMS (0.707 X 500) to modulate it. Find the transformation windings that give you the closest match to get this voltage output. Your 25 watt amp is capable of putting out 20 volts RMS into 16 ohms or about 14 volts into 8 ohms or 112 volts for 500 ohm line. If you had more audio power available then your options would be more. If the power XFMR is about 360 volts either side of CT then use CT to one one side (half of the secondary) for the plate circuit and input 500 ohms to the 115 Volt AC of the primary. You will use the DX 60 in the CW mode and connect the HV secondary of the outboard matching XFMR so that the B+ for the final and the screen resistor connection point are together and their current has to pass thru the XFMR to work. Check with other diagrams of 6146 plate modulated rigs in the older handbooks and you will get the idea. Good Luck John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Harry Vaught Sent: Friday, March 17, 2006 7:13 AM To: Discussion of AM Radio Subject: Re: [AMRadio] Amplifier to use with my DX-60 Ok, tell me this: I have a DX-60A and a 25 watt P-P 6L6 Webster Electric PA amp with a large selection of output impedances. What would I have to do to plate modulate my DX-60? There are obviously greatly varying levels of knowledge out there, and mine is probably below median. Harry, KT4AE Maryville, Tennessee __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
Re: [AMRadio] Amplifier to use with my DX-60
Get a large old TV power transformer. Use the high voltage to feed the 6146 and the 115 volt winding or filament windings to match to the amplifier output. You can use a 4500 ohm resistor of 20 watts across the highvoltage winding and look at it with a scope. Select the winding on the TV xfmr and the amp output tap that gives the best waveform with a 2 tone or 1000kc signal thru the amp. Other wise find an old tube amp with 30 watts or better output and remove the output transformer. Hook it reversed from the amp output to the 6146. I've used both systems will good results. Healthfully yours, DON W4BWS - Original Message - From: "Harry Vaught" <[EMAIL PROTECTED]> To: "Discussion of AM Radio" Sent: Friday, March 17, 2006 7:13 AM Subject: Re: [AMRadio] Amplifier to use with my DX-60 > Ok, tell me this: > > I have a DX-60A and a 25 watt P-P 6L6 Webster Electric PA amp with a > large selection of output impedances. What would I have to do to plate > modulate my DX-60? > > There are obviously greatly varying levels of knowledge out there, and > mine is probably below median. > > Harry, KT4AE > Maryville, Tennessee > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb >
RE: [AMRadio] Amplifier to use with my DX-60
Yep, there is no doubt that the pair of 3-500Zs and getting rid of the control carrier on the DX60 would be better but a lot more expense I think. Aren't 3-500Zs pretty expensive? John -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim candela Sent: Friday, March 17, 2006 10:00 AM To: Discussion of AM Radio Subject: RE: [AMRadio] Amplifier to use with my DX-60 John, Your approach as always is a good one, and can be made to work out quite well. This extra box will allow about a 6DB increase in power from what a screen modulated 6146 can do. The DX-60 with carrier control can arguably better match up to a linear amplifier, but must of us would agree that carrier control as done on this rig is too much, and annoying to those copying a weak signal that goes into and out of the noise with modulation peaks. Now consider these options: 1.) Modify the DX-60 for non carrier control screen modulation. That should provide about 20 watts carrier with room for + 100% modulation. 2.) Modify the DX-60 for plate modulation. This might require a 6146 bias change for proper class C plate modulation bias. You will also have to deal with modulating the screen grid. The plate tuning capacitor might flash over, and other components may need to be beefed up to handle the higher peak power. Once done, you will have a fine 45-50 watt AM rig that you could be proud of. 3.) Combine option 1 with this: Mate up the modified DX-60 to a linear with 1000 watts of dissipation available (like two 3-500Z's). Now you can easily run 250 watts AM or more (maybe 375) of quality AM. 4.) Use the DX-60 as is (stock), or with an amplifier as you wish. The choice is yours, Jim WD5JKO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of John E. Coleman (ARS WA5BXO) Sent: Thursday, March 16, 2006 9:10 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] Amplifier to use with my DX-60 I still say, forget the linear, and use less money to build a plate modulator for the DX60. It will work better, sound better, cost less, and heat the shack up less. As I recall the DX 60 has a 6146 in the final for class C CW and puts out about 40-50 watts of carrier if it were plate modulated it would do at least 200 watts PEP and sound great. There is a number of different ways to do the modulator. A lot of guys just find and old PA and a transformer to match to the final. Some build the modulator output stages only, input XFMR tubes and modulation XFMR. Then they drive it with a small microphone amp. That's more stuff to set around on the desk but it works. There are a lot of self contained 25 and 50 watt modulator circuits around and probably a lot of complete one piece store bought modulators as well. As I recall, EICO had a pretty nice one that was to go with the EICO model 720 but it was used on many different rigs as well as being used as a driver for big modulators. A buddy of mine had an ECIO 720 and built a nice home brewed modulator for it using 1625s in AB1. It sounded real good. I built one similar to it with less power output for my Knight Kit T60. The T60 had the same control carrier AM that the DX60 does. What a difference it made when it was plate modulated. Very little modification is necessary in the DX60 to accommodate the external modulator. John, WA5BXO __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006 __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] Amplifier to use with my DX-60
John, Your approach as always is a good one, and can be made to work out quite well. This extra box will allow about a 6DB increase in power from what a screen modulated 6146 can do. The DX-60 with carrier control can arguably better match up to a linear amplifier, but must of us would agree that carrier control as done on this rig is too much, and annoying to those copying a weak signal that goes into and out of the noise with modulation peaks. Now consider these options: 1.) Modify the DX-60 for non carrier control screen modulation. That should provide about 20 watts carrier with room for + 100% modulation. 2.) Modify the DX-60 for plate modulation. This might require a 6146 bias change for proper class C plate modulation bias. You will also have to deal with modulating the screen grid. The plate tuning capacitor might flash over, and other components may need to be beefed up to handle the higher peak power. Once done, you will have a fine 45-50 watt AM rig that you could be proud of. 3.) Combine option 1 with this: Mate up the modified DX-60 to a linear with 1000 watts of dissipation available (like two 3-500Z's). Now you can easily run 250 watts AM or more (maybe 375) of quality AM. 4.) Use the DX-60 as is (stock), or with an amplifier as you wish. The choice is yours, Jim WD5JKO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of John E. Coleman (ARS WA5BXO) Sent: Thursday, March 16, 2006 9:10 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] Amplifier to use with my DX-60 I still say, forget the linear, and use less money to build a plate modulator for the DX60. It will work better, sound better, cost less, and heat the shack up less. As I recall the DX 60 has a 6146 in the final for class C CW and puts out about 40-50 watts of carrier if it were plate modulated it would do at least 200 watts PEP and sound great. There is a number of different ways to do the modulator. A lot of guys just find and old PA and a transformer to match to the final. Some build the modulator output stages only, input XFMR tubes and modulation XFMR. Then they drive it with a small microphone amp. That's more stuff to set around on the desk but it works. There are a lot of self contained 25 and 50 watt modulator circuits around and probably a lot of complete one piece store bought modulators as well. As I recall, EICO had a pretty nice one that was to go with the EICO model 720 but it was used on many different rigs as well as being used as a driver for big modulators. A buddy of mine had an ECIO 720 and built a nice home brewed modulator for it using 1625s in AB1. It sounded real good. I built one similar to it with less power output for my Knight Kit T60. The T60 had the same control carrier AM that the DX60 does. What a difference it made when it was plate modulated. Very little modification is necessary in the DX60 to accommodate the external modulator. John, WA5BXO __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006
Re: [AMRadio] Amplifier to use with my DX-60
You have an interesting point here John. I don't know if I have access to enough "STUFF" to do a job like that, I am fairly isolated here on PEI. It is almost better to find a Johnson Transmitter or something. I AM going to try a 160 meter end fed Zepp to get some height and gain off my antenna. Cheers, Alan John E. Coleman (ARS WA5BXO) wrote: I still say, forget the linear, and use less money to build a plate modulator for the DX60. It will work better, sound better, cost less, and heat the shack up less. As I recall the DX 60 has a 6146 in the final for class C CW and puts out about 40-50 watts of carrier if it were plate modulated it would do at least 200 watts PEP and sound great. There is a number of different ways to do the modulator. A lot of guys just find and old PA and a transformer to match to the final. Some build the modulator output stages only, input XFMR tubes and modulation XFMR. Then they drive it with a small microphone amp. That's more stuff to set around on the desk but it works. There are a lot of self contained 25 and 50 watt modulator circuits around and probably a lot of complete one piece store bought modulators as well. As I recall, EICO had a pretty nice one that was to go with the EICO model 720 but it was used on many different rigs as well as being used as a driver for big modulators. A buddy of mine had an ECIO 720 and built a nice home brewed modulator for it using 1625s in AB1. It sounded real good. I built one similar to it with less power output for my Knight Kit T60. The T60 had the same control carrier AM that the DX60 does. What a difference it made when it was plate modulated. Very little modification is necessary in the DX60 to accommodate the external modulator. John, WA5BXO __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
Re: [AMRadio] Amplifier to use with my DX-60
Thank you Tom. ;-) I love been a thread seed. You guys have all been great in helping me decide which linear to seek out in the Heathkit cheapo line. so, is the 220/230 the best choice to get the job done. I think from what I am seeing here that the 200 just would not cut it. 73, Alan [EMAIL PROTECTED] wrote: If I understand these responses this all boils down to answer Alan's original question and that is that a SB-200 would be ok with the DX-60 at the DX-60's max output . Correct? Tom K3TVC - Original Message - From: "Mike Dorworth, K4XM" <[EMAIL PROTECTED]> To: "Discussion of AM Radio" Sent: Thursday, March 16, 2006 5:45 PM Subject: Re: [AMRadio] Amplifier to use with my DX-60 YUP. The two things are the tubes and the power supply.. One half dissipation is MAX.. you are using 800 watt tubes so 400Watt carrier is max. The Thunderbolt has a real power supply, so, sure 300 watts is fine.Since SSB is 25 to 30 percent average of peaks the manufactures can squeeze in small supplies for voice or CW service. Ever make you wonder that they might allow 2500 watts input SSB but only 400 for RTTY. AM and RTTY separates the Men from the boys.. Mike - Original Message - From: "Dale Smith" <[EMAIL PROTECTED]> To: "Mike Dorworth, K4XM" <[EMAIL PROTECTED]>; "Discussion of AM Radio" Sent: Thursday, March 16, 2006 5:43 PM Subject: Re: [AMRadio] Amplifier to use with my DX-60 How about a Johnson thunder bolt is 300 watt carrier ok ? I hope so cause that is what I have been doing The transformer in there is twice as big as my swan mark 1. thanks ..de/dale/ka5who __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
Re: [AMRadio] Amplifier to use with my DX-60
Ok, tell me this: I have a DX-60A and a 25 watt P-P 6L6 Webster Electric PA amp with a large selection of output impedances. What would I have to do to plate modulate my DX-60? There are obviously greatly varying levels of knowledge out there, and mine is probably below median. Harry, KT4AE Maryville, Tennessee
Re: [AMRadio] Amplifier to use with my DX-60
My main concern Don is that giving out a calculated carrier level for a set of tubes to a guy who does not have a scope and audio generator is not going to give the amateur band another clean signal. As I mentioned in a previous email, I have been unable to obtain the efficiencies you mention and would like to hear from someone who can measure everything with test equipment and tell me about it. Thanks, Ken W2DTC From: "kenw2dtc" <[EMAIL PROTECTED]> Don says: "So you could run maximum 1500 watts DC input to those tubes, with 500 watts carrier output, and 1000 watts dissipated by the tubes" ***I need a little help with the math here Don. You are suggesting that with a class B linear in AM mode, one can get 2000 watts PEP with 1500 watts input ? Assuming 100% positive peak modulation, yes. ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/ __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] Amplifier to use with my DX-60
I still say, forget the linear, and use less money to build a plate modulator for the DX60. It will work better, sound better, cost less, and heat the shack up less. As I recall the DX 60 has a 6146 in the final for class C CW and puts out about 40-50 watts of carrier if it were plate modulated it would do at least 200 watts PEP and sound great. There is a number of different ways to do the modulator. A lot of guys just find and old PA and a transformer to match to the final. Some build the modulator output stages only, input XFMR tubes and modulation XFMR. Then they drive it with a small microphone amp. That's more stuff to set around on the desk but it works. There are a lot of self contained 25 and 50 watt modulator circuits around and probably a lot of complete one piece store bought modulators as well. As I recall, EICO had a pretty nice one that was to go with the EICO model 720 but it was used on many different rigs as well as being used as a driver for big modulators. A buddy of mine had an ECIO 720 and built a nice home brewed modulator for it using 1625s in AB1. It sounded real good. I built one similar to it with less power output for my Knight Kit T60. The T60 had the same control carrier AM that the DX60 does. What a difference it made when it was plate modulated. Very little modification is necessary in the DX60 to accommodate the external modulator. John, WA5BXO
Re: [AMRadio] Amplifier to use with my DX-60
From: "kenw2dtc" <[EMAIL PROTECTED]> Don says: "So you could run maximum 1500 watts DC input to those tubes, with 500 watts carrier output, and 1000 watts dissipated by the tubes" ***I need a little help with the math here Don. You are suggesting that with a class B linear in AM mode, one can get 2000 watts PEP with 1500 watts input ? Assuming 100% positive peak modulation, yes. ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] Amplifier to use with my DX-60
Thanks so much for taking the time to remind me about all this stuff!!! When I was 25 I worked on a Gates 50B that was as old as I was. I mostly just monitored voltages and looked for trouble. I was facsinated back then as I find myself being now while I foray into the world of AM again. I spent too much time in Broadcast as a studio tech. Cheers, Alan VY2WU Quoting Donald Chester <[EMAIL PROTECTED]>: > > > > >From: Alan Beck <[EMAIL PROTECTED]> > > >I would like to use a cheap am with my DX-60. > > > >An SB-200-230 seems to be a Class B amp. There for it only conducts on the > >positive going cycle. I don't mean to sound silly, but someone told me I > >could run this in SSB Mode using AM input from my DX-60, I run 100 Watts > >carrier for 400 Watts peak, now that makes sense. > > > >What does not make sense is how do I get the other side of the wave > >form The Tank??? I guess the tank. > > > > The linear will work on AM as long as you don't exceed the peak power output > > rating. Exceeding the peak output rating will cause the signal to flat-top, > > distort and splatter. > > Another thing to watch for is the plate dissipation of the tubes. If I > recall correctly, the SB-200 series uses a pair of 3-500Z tubes in the > final. That means you have 1000 watts of plate dissipation available. > Running AM linear @ 100% modulation will give carrier output efficiency of > about 30%. So you could run maximum 1500 watts DC input to those tubes, > with 500 watts carrier output, and 1000 watts dissipated by the tubes. With > > modulation, the tubes will actually cool down slightly, since the DC input > will not vary, but the amplifier will deliver sideband power in addition to > carrier power output. So some of the input power will be converted to rf in > > the sidebands instead of heat in the tube plates. > > But you also have to be careful with the power supply. AM runs at 100% duty > > cycle, so the power supply in the amplifier may not be rated to run 1500 > watts continuous duty. After a few minutes, the power transformer may > overheat. In that case you will have to run it at reduced power. But be > careful that the plate efficiency does not exceed about 33%. If you run it > at too high plate efficiency, it will not leave you enough headroom to > accomodate the positive peaks, and flat-topping/distortion/splatter will > result. > > Don't worry about the missing half of the rf cycle. It works with AM > exactly the same way as it does with SSB. Since the amplifier is single > ended and not pushpull, the missing half of the rf cycle is filled in by the > > "flywheel effect" of the rf tank circuit. > > In summary, with class-B linear AM operation, the final will run about 33% > carrier efficiency. The peak efficiency on modulation peaks will be about > double that, 67%. Two-thirds of the DC input to the final will be > dissipated as heat in the plates of the tubes under carrier-only, no > modulation conditions. That means the carrier output will be one half the > plate dissipation of the tubes. The peak power output should be about 4 > times the resting carrier output at 100% modulation, if flat-topping is to > be avoided. > > Linear amplifier AM operation dates back to the very earliest days of radio. > > The earliest high power broadcast stations used it. It was used for years > > before anyone figured out how to run audio amplifiers in class-B. Before > then, the only kind of high level plate modulation that was used employed > class A audio amplifiers, usually the "Heising" circuit but sometimes series > > modulation was used. Both those systems ran at lower ovarall efficiency > than linear rf amplification. Therefore, AM linears were used long before > high level plate modulation for high powered AM transmitters. > _ > > This message was typed using the DVORAK keyboard layout. Try it - you'll > like it. > http://www.mwbrooks.com/dvorak/ > http://gigliwood.com/abcd/ > > > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb >
Re: [AMRadio] Amplifier to use with my DX-60
The SB-200 uses two 572B's. The SB-220 is the amp that uses two 3-500Z's. Joe W4AAB - Original Message - From: "Donald Chester" <[EMAIL PROTECTED]> To: Sent: Thursday, March 16, 2006 3:48 PM Subject: RE: [AMRadio] Amplifier to use with my DX-60 > > > > >From: Alan Beck <[EMAIL PROTECTED]> > > >I would like to use a cheap am with my DX-60. > > > >An SB-200-230 seems to be a Class B amp. There for it only conducts on the > >positive going cycle. I don't mean to sound silly, but someone told me I > >could run this in SSB Mode using AM input from my DX-60, I run 100 Watts > >carrier for 400 Watts peak, now that makes sense. > > > >What does not make sense is how do I get the other side of the wave > >form The Tank??? I guess the tank. > > > > The linear will work on AM as long as you don't exceed the peak power output > rating. Exceeding the peak output rating will cause the signal to flat-top, > distort and splatter. > > Another thing to watch for is the plate dissipation of the tubes. If I > recall correctly, the SB-200 series uses a pair of 3-500Z tubes in the > final. That means you have 1000 watts of plate dissipation available. > Running AM linear @ 100% modulation will give carrier output efficiency of > about 30%. So you could run maximum 1500 watts DC input to those tubes, > with 500 watts carrier output, and 1000 watts dissipated by the tubes. With > modulation, the tubes will actually cool down slightly, since the DC input > will not vary, but the amplifier will deliver sideband power in addition to > carrier power output. So some of the input power will be converted to rf in > the sidebands instead of heat in the tube plates. > > But you also have to be careful with the power supply. AM runs at 100% duty > cycle, so the power supply in the amplifier may not be rated to run 1500 > watts continuous duty. After a few minutes, the power transformer may > overheat. In that case you will have to run it at reduced power. But be > careful that the plate efficiency does not exceed about 33%. If you run it > at too high plate efficiency, it will not leave you enough headroom to > accomodate the positive peaks, and flat-topping/distortion/splatter will > result. > > Don't worry about the missing half of the rf cycle. It works with AM > exactly the same way as it does with SSB. Since the amplifier is single > ended and not pushpull, the missing half of the rf cycle is filled in by the > "flywheel effect" of the rf tank circuit. > > In summary, with class-B linear AM operation, the final will run about 33% > carrier efficiency. The peak efficiency on modulation peaks will be about > double that, 67%. Two-thirds of the DC input to the final will be > dissipated as heat in the plates of the tubes under carrier-only, no > modulation conditions. That means the carrier output will be one half the > plate dissipation of the tubes. The peak power output should be about 4 > times the resting carrier output at 100% modulation, if flat-topping is to > be avoided. > > Linear amplifier AM operation dates back to the very earliest days of radio. > The earliest high power broadcast stations used it. It was used for years > before anyone figured out how to run audio amplifiers in class-B. Before > then, the only kind of high level plate modulation that was used employed > class A audio amplifiers, usually the "Heising" circuit but sometimes series > modulation was used. Both those systems ran at lower ovarall efficiency > than linear rf amplification. Therefore, AM linears were used long before > high level plate modulation for high powered AM transmitters. > _ > > This message was typed using the DVORAK keyboard layout. Try it - you'll > like it. > http://www.mwbrooks.com/dvorak/ > http://gigliwood.com/abcd/ > > > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb >
Re: [AMRadio] Amplifier to use with my DX-60
Jim, I guess my question is really: Can anyone actually demonstrate a real AM linear that can output 500 watts carrier and show 2000 watts PEP into a dummy load with a nice looking audio sine wave on the scope, from the RF pickup, while running 1500 watts DC input ? If so, please send me an email at [EMAIL PROTECTED] The reason I ask is: A. None of my amps has ever been that good and B. Unfortunately, a number of people running AM linears do not have scopes and if you tell them that a pair of whatever tubes can achieve a certain carrier power, they will put the carrier to that level via dipping and peaking the pi-net until their wattmeter reaches the specified power and talk. In my experience, by the time you heavily load the output to achieve the perfect audio sine wave, your tuning controls are quite different than what is was when you peaked everything and the efficiency is no longer as good as what the calculations show. On top of that most male voices have peaks that should have an additional de-rating of output power. So when someone asks about what kind of carrier power a certain pair of tubes can put out in AM linear service, I really like to give a conservative number, not the math numbers. 73, Ken W2DTC __ Ken Barber Middletown, NJ Radio Website: http://w2dtc.com Family Photos: http://kenw2dtc.home.comcast.net __ - Original Message - From: "Jim candela" <[EMAIL PROTECTED]> To: "Discussion of AM Radio" Sent: Thursday, March 16, 2006 7:22 PM Subject: RE: [AMRadio] Amplifier to use with my DX-60 Don, You said: "So you could run maximum 1500 watts DC input to those tubes, with 500 watts carrier output, and 1000 watts dissipated by the tubes". Reply from Jim WD5JKO: What is stated above is correct if the tubes can dissipate 1000 watts of heat (like two 3-500Z's flat out blushing), and the drive is adjusted to about 1/4th that for maximum PEP output. In this case the efficiency is assummed to be about 33%, so 1500 X .333 = 500 watts. The efficiency may vary some, and is usually lower then that, so the 33% assumption is only a first guess. It could be 25%, and that really upsets the situation making the linear more of a heater, and less of a transmitter. One good thing about the 1500 watt PEP output power rule we all complain about is that efficiency doesn't matter as much now. You can legally run a 15 KW PEP input amplifier with 10% efficiency to provide 1500 watts PEP output. It wouldn't make a lot of sense, or be practical, but it's now legal. Back in the 1000 watts DC input days things were a lot different, and the SB-220's input would likely exceed 1000 watts DC before the AM carrier got to 375 like we often do today with these amps. The point here is that for low efficiency linears, or grid modulated amplifiers, we can sometimes run more power today on AM then before the rules changed from 1000 watts DC input to 1500 watts PEP output. Of course this isn't the case with plate modulation where an output PEP at or maybe more than 3KW PEP WAS possible, and completely legal. Regards, Jim WD5JKO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of kenw2dtc Sent: Thursday, March 16, 2006 4:21 PM To: Discussion of AM Radio Subject: Re: [AMRadio] Amplifier to use with my DX-60 Don says: "So you could run maximum 1500 watts DC input to those tubes, with 500 watts carrier output, and 1000 watts dissipated by the tubes" ***I need a little help with the math here Don. You are suggesting that with a class B linear in AM mode, one can get 2000 watts PEP with 1500 watts input ? 73, Ken W2DTC __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006 __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
Re: [AMRadio] Amplifier to use with my DX-60
Yes, those numbers are possible in amateur service. When I ran a pair of 3-400s linear, I ran about 800 watts carrier input, I got about 160 watts carrier output, disspipation about 640 watts, 200 % mod, and about 1500 PEP out. (Efficiency gets bad when you set them up that way.) If I turned the audio down to about 100%, I could raise the carrier level and get 350 watts carrier output, carrier input about 1100 watts, PEP about 1500 watts, dissipation about 750 watts. The tubes did get hot that way, though. Bacon, WA3WDR - Original Message - From: "Jim candela" <[EMAIL PROTECTED]> To: "Discussion of AM Radio" Sent: Thursday, March 16, 2006 7:22 PM Subject: RE: [AMRadio] Amplifier to use with my DX-60 > > Don, > >You said: "So you could run maximum 1500 watts DC input to those tubes, > with 500 watts > carrier output, and 1000 watts dissipated by the tubes". > > Reply from Jim WD5JKO: > >What is stated above is correct if the tubes can dissipate 1000 watts of > heat (like two 3-500Z's flat out blushing), and the drive is adjusted to > about 1/4th that for maximum PEP output. In this case the efficiency is > assummed to be about 33%, so 1500 X .333 = 500 watts. The efficiency may > vary some, and is usually lower then that, so the 33% assumption is only a > first guess. It could be 25%, and that really upsets the situation making > the linear more of a heater, and less of a transmitter. > >One good thing about the 1500 watt PEP output power rule we all complain > about is that efficiency doesn't matter as much now. You can legally run a > 15 KW PEP input amplifier with 10% efficiency to provide 1500 watts PEP > output. It wouldn't make a lot of sense, or be practical, but it's now > legal. Back in the 1000 watts DC input days things were a lot different, and > the SB-220's input would likely exceed 1000 watts DC before the AM carrier > got to 375 like we often do today with these amps. The point here is that > for low efficiency linears, or grid modulated amplifiers, we can sometimes > run more power today on AM then before the rules changed from 1000 watts DC > input to 1500 watts PEP output. Of course this isn't the case with plate > modulation where an output PEP at or maybe more than 3KW PEP WAS possible, > and completely legal. > > Regards, > Jim > WD5JKO > > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf Of kenw2dtc > Sent: Thursday, March 16, 2006 4:21 PM > To: Discussion of AM Radio > Subject: Re: [AMRadio] Amplifier to use with my DX-60 > > > Don says: > > "So you could run maximum 1500 watts DC input to those tubes, with 500 watts > carrier output, and 1000 watts dissipated by the tubes" > > ***I need a little help with the math here Don. You are suggesting that > with a class B linear in AM mode, one can get 2000 watts PEP with 1500 watts > input ? > > 73, > Ken W2DTC > > ___ ___ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006 > > -- > No virus found in this outgoing message. > Checked by AVG Free Edition. > Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006 > > ___ ___ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb >
RE: [AMRadio] Amplifier to use with my DX-60
Don, You said: "So you could run maximum 1500 watts DC input to those tubes, with 500 watts carrier output, and 1000 watts dissipated by the tubes". Reply from Jim WD5JKO: What is stated above is correct if the tubes can dissipate 1000 watts of heat (like two 3-500Z's flat out blushing), and the drive is adjusted to about 1/4th that for maximum PEP output. In this case the efficiency is assummed to be about 33%, so 1500 X .333 = 500 watts. The efficiency may vary some, and is usually lower then that, so the 33% assumption is only a first guess. It could be 25%, and that really upsets the situation making the linear more of a heater, and less of a transmitter. One good thing about the 1500 watt PEP output power rule we all complain about is that efficiency doesn't matter as much now. You can legally run a 15 KW PEP input amplifier with 10% efficiency to provide 1500 watts PEP output. It wouldn't make a lot of sense, or be practical, but it's now legal. Back in the 1000 watts DC input days things were a lot different, and the SB-220's input would likely exceed 1000 watts DC before the AM carrier got to 375 like we often do today with these amps. The point here is that for low efficiency linears, or grid modulated amplifiers, we can sometimes run more power today on AM then before the rules changed from 1000 watts DC input to 1500 watts PEP output. Of course this isn't the case with plate modulation where an output PEP at or maybe more than 3KW PEP WAS possible, and completely legal. Regards, Jim WD5JKO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of kenw2dtc Sent: Thursday, March 16, 2006 4:21 PM To: Discussion of AM Radio Subject: Re: [AMRadio] Amplifier to use with my DX-60 Don says: "So you could run maximum 1500 watts DC input to those tubes, with 500 watts carrier output, and 1000 watts dissipated by the tubes" ***I need a little help with the math here Don. You are suggesting that with a class B linear in AM mode, one can get 2000 watts PEP with 1500 watts input ? 73, Ken W2DTC __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006
Re: [AMRadio] Amplifier to use with my DX-60
YES,in fact he could. 100 watts carrier or 80 watts carrier. The power supply is the limiting factor here. The SB200 with a big fan and an external power supply could actually run 160 watts carrier. The word Max is actually maximum. The wimpy supply holds it to about 80 watts. You might like the smell of hot tar and burned kraft paper! I would stick to 80 watts or there abouts and check the transformer with the " can I hold a finger full on it for 3 full seconds" test.. Mike > If I understand these responses this all boils down to answer Alan's > original question and that is that a SB-200 would be ok with the DX-60 at > the DX-60's max output . Correct? > > Tom K3TVC >An SB-200-230 seems to be a Class B amp. There for it only conducts on the > >positive going cycle. I don't mean to sound silly, but someone told me I > >could run this in SSB Mode using AM input from my DX-60, I run 100 Watts > >carrier for 400 Watts peak, now that makes sense. > >
Re: [AMRadio] Amplifier to use with my DX-60
If I understand these responses this all boils down to answer Alan's original question and that is that a SB-200 would be ok with the DX-60 at the DX-60's max output . Correct? Tom K3TVC - Original Message - From: "Mike Dorworth, K4XM" <[EMAIL PROTECTED]> To: "Discussion of AM Radio" Sent: Thursday, March 16, 2006 5:45 PM Subject: Re: [AMRadio] Amplifier to use with my DX-60 > YUP. The two things are the tubes and the power supply.. One half > dissipation is MAX.. you are using 800 watt tubes so 400Watt carrier is max. > The Thunderbolt has a real power supply, so, sure 300 watts is fine.Since > SSB is 25 to 30 percent average of peaks the manufactures can squeeze in > small supplies for voice or CW service. Ever make you wonder that they might > allow 2500 watts input SSB but only 400 for RTTY. AM and RTTY separates the > Men from the boys.. Mike > - Original Message - > From: "Dale Smith" <[EMAIL PROTECTED]> > To: "Mike Dorworth, K4XM" <[EMAIL PROTECTED]>; "Discussion of AM Radio" > > Sent: Thursday, March 16, 2006 5:43 PM > Subject: Re: [AMRadio] Amplifier to use with my DX-60 > > > > How about a Johnson thunder bolt is 300 watt carrier ok ? I hope so > > cause that is what I have been doing > > The transformer in there is twice as big as my swan mark 1. > > thanks ..de/dale/ka5who > > > > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb >
Re: [AMRadio] Amplifier to use with my DX-60
YUP. The two things are the tubes and the power supply.. One half dissipation is MAX.. you are using 800 watt tubes so 400Watt carrier is max. The Thunderbolt has a real power supply, so, sure 300 watts is fine.Since SSB is 25 to 30 percent average of peaks the manufactures can squeeze in small supplies for voice or CW service. Ever make you wonder that they might allow 2500 watts input SSB but only 400 for RTTY. AM and RTTY separates the Men from the boys.. Mike - Original Message - From: "Dale Smith" <[EMAIL PROTECTED]> To: "Mike Dorworth, K4XM" <[EMAIL PROTECTED]>; "Discussion of AM Radio" Sent: Thursday, March 16, 2006 5:43 PM Subject: Re: [AMRadio] Amplifier to use with my DX-60 > How about a Johnson thunder bolt is 300 watt carrier ok ? I hope so > cause that is what I have been doing > The transformer in there is twice as big as my swan mark 1. > thanks ..de/dale/ka5who >
Re: [AMRadio] Amplifier to use with my DX-60
How about a Johnson thunder bolt is 300 watt carrier ok ? I hope so cause that is what I have been doing The transformer in there is twice as big as my swan mark 1. thanks ..de/dale/ka5who
Re: [AMRadio] Amplifier to use with my DX-60
Don says: "So you could run maximum 1500 watts DC input to those tubes, with 500 watts carrier output, and 1000 watts dissipated by the tubes" ***I need a little help with the math here Don. You are suggesting that with a class B linear in AM mode, one can get 2000 watts PEP with 1500 watts input ? 73, Ken W2DTC
Re: [AMRadio] Amplifier to use with my DX-60
Short answer. The SB200 uses a pair of 572B/T160L rated at 160 watts each. AM Linear output can not be more than one half of total dissipation. The power supplies are usually rated for continous service (AM) at 25 percent of the peak. For SB220 a 400 watt transformer is used for 2000 watts pep input. The SB200 is rated at 1200 watts pep input and would have about a 300 watt transformer. If the supply were strong enough the SB200 could run 160 watts carrier. Best to stick with one half of that..80 watts. For the SB220, L4B, TL922A best to stick with 250 watts carrier, or less. The answer below is exactly correct except for the tubes in the SB200.. The SB230 uses a conduction cooled 8873 with about 300 watts dissipation, 80 watts carrier would probably cook it in short order because of the non-cooling system heat load. 73 Mike - Original Message - From: "Donald Chester" <[EMAIL PROTECTED]> To: Sent: Thursday, March 16, 2006 4:48 PM Subject: RE: [AMRadio] Amplifier to use with my DX-60 > > > > >From: Alan Beck <[EMAIL PROTECTED]> > > >I would like to use a cheap am with my DX-60. > > > >An SB-200-230 seems to be a Class B amp. There for it only conducts on the > >positive going cycle. I don't mean to sound silly, but someone told me I > >could run this in SSB Mode using AM input from my DX-60, I run 100 Watts > >carrier for 400 Watts peak, now that makes sense. > > > >What does not make sense is how do I get the other side of the wave > >form The Tank??? I guess the tank. > > > > The linear will work on AM as long as you don't exceed the peak power output > rating. Exceeding the peak output rating will cause the signal to flat-top, > distort and splatter. > > Another thing to watch for is the plate dissipation of the tubes. If I > recall correctly, the SB-200 series uses a pair of 3-500Z tubes in the > final. That means you have 1000 watts of plate dissipation available. > Running AM linear @ 100% modulation will give carrier output efficiency of > about 30%. So you could run maximum 1500 watts DC input to those tubes, > with 500 watts carrier output, and 1000 watts dissipated by the tubes. With > modulation, the tubes will actually cool down slightly, since the DC input > will not vary, but the amplifier will deliver sideband power in addition to > carrier power output. So some of the input power will be converted to rf in > the sidebands instead of heat in the tube plates. > > But you also have to be careful with the power supply. AM runs at 100% duty > cycle, so the power supply in the amplifier may not be rated to run 1500 > watts continuous duty. After a few minutes, the power transformer may > overheat. In that case you will have to run it at reduced power. But be > careful that the plate efficiency does not exceed about 33%. If you run it > at too high plate efficiency, it will not leave you enough headroom to > accomodate the positive peaks, and flat-topping/distortion/splatter will > result. > > Don't worry about the missing half of the rf cycle. It works with AM > exactly the same way as it does with SSB. Since the amplifier is single > ended and not pushpull, the missing half of the rf cycle is filled in by the > "flywheel effect" of the rf tank circuit. > > In summary, with class-B linear AM operation, the final will run about 33% > carrier efficiency. The peak efficiency on modulation peaks will be about > double that, 67%. Two-thirds of the DC input to the final will be > dissipated as heat in the plates of the tubes under carrier-only, no > modulation conditions. That means the carrier output will be one half the > plate dissipation of the tubes. The peak power output should be about 4 > times the resting carrier output at 100% modulation, if flat-topping is to > be avoided. > > Linear amplifier AM operation dates back to the very earliest days of radio. > The earliest high power broadcast stations used it. It was used for years > before anyone figured out how to run audio amplifiers in class-B. Before > then, the only kind of high level plate modulation that was used employed > class A audio amplifiers, usually the "Heising" circuit but sometimes series > modulation was used. Both those systems ran at lower ovarall efficiency > than linear rf amplification. Therefore, AM linears were used long before > high level plate modulation for high powered AM transmitters. > _ > > This message was typed using the DVORAK keyboard layout. Try it - you'll > like it. > http://www.mwbrooks.com/dvorak/ > http://gigliwood.com/abcd/ > > > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb > >
RE: [AMRadio] Amplifier to use with my DX-60
From: Alan Beck <[EMAIL PROTECTED]> I would like to use a cheap am with my DX-60. An SB-200-230 seems to be a Class B amp. There for it only conducts on the positive going cycle. I don't mean to sound silly, but someone told me I could run this in SSB Mode using AM input from my DX-60, I run 100 Watts carrier for 400 Watts peak, now that makes sense. What does not make sense is how do I get the other side of the wave form The Tank??? I guess the tank. The linear will work on AM as long as you don't exceed the peak power output rating. Exceeding the peak output rating will cause the signal to flat-top, distort and splatter. Another thing to watch for is the plate dissipation of the tubes. If I recall correctly, the SB-200 series uses a pair of 3-500Z tubes in the final. That means you have 1000 watts of plate dissipation available. Running AM linear @ 100% modulation will give carrier output efficiency of about 30%. So you could run maximum 1500 watts DC input to those tubes, with 500 watts carrier output, and 1000 watts dissipated by the tubes. With modulation, the tubes will actually cool down slightly, since the DC input will not vary, but the amplifier will deliver sideband power in addition to carrier power output. So some of the input power will be converted to rf in the sidebands instead of heat in the tube plates. But you also have to be careful with the power supply. AM runs at 100% duty cycle, so the power supply in the amplifier may not be rated to run 1500 watts continuous duty. After a few minutes, the power transformer may overheat. In that case you will have to run it at reduced power. But be careful that the plate efficiency does not exceed about 33%. If you run it at too high plate efficiency, it will not leave you enough headroom to accomodate the positive peaks, and flat-topping/distortion/splatter will result. Don't worry about the missing half of the rf cycle. It works with AM exactly the same way as it does with SSB. Since the amplifier is single ended and not pushpull, the missing half of the rf cycle is filled in by the "flywheel effect" of the rf tank circuit. In summary, with class-B linear AM operation, the final will run about 33% carrier efficiency. The peak efficiency on modulation peaks will be about double that, 67%. Two-thirds of the DC input to the final will be dissipated as heat in the plates of the tubes under carrier-only, no modulation conditions. That means the carrier output will be one half the plate dissipation of the tubes. The peak power output should be about 4 times the resting carrier output at 100% modulation, if flat-topping is to be avoided. Linear amplifier AM operation dates back to the very earliest days of radio. The earliest high power broadcast stations used it. It was used for years before anyone figured out how to run audio amplifiers in class-B. Before then, the only kind of high level plate modulation that was used employed class A audio amplifiers, usually the "Heising" circuit but sometimes series modulation was used. Both those systems ran at lower ovarall efficiency than linear rf amplification. Therefore, AM linears were used long before high level plate modulation for high powered AM transmitters. _ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] Amplifier to use with my DX-60
Alan, most all tube type linear amps are class B, or AB and can be single ended or push-pull. In RF service the tank tuning takes care of the output wave distortion making nice pretty sine waves. Linear amps are not class C because class C is really more like a switch than an amplifier. In most class C finals you can vary the input some and it will not make any difference in the output. For this reason they or good for CW and plate modulated AM. Class C finals have a characteristic of the output following the plate supply voltage up and down linearly. If the plate supply is dropped to half the RF output voltage will drop to half, and so on. For this reason the audio is inserted in the plate power supply line, hence plate modulated. As for power levels, an SB200 is only about 3DBs better than getting rid of the control carrier modulator in the DX 60 (put it in the CW position) and building an external plate modulator for it. And it will sound a lot better. It is a really cheap project too. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Alan Beck Sent: Thursday, March 16, 2006 8:34 AM To: Discussion of AM Radio Subject: [AMRadio] Amplifier to use with my DX-60 I would like to use a cheap am with my DX-60. An SB-200-230 seems to be a Class B amp. There for it only conducts on the positive going cycle. I don't mean to sound silly, but someone told me I could run this in SSB Mode using AM input from my DX-60, I run 100 Watts carrier for 400 Watts peak, now that makes sense. What does not make sense is how do I get the other side of the wave form The Tank??? I guess the tank. I really need to go cheap on this project. I know, you guys will probably say "go big or go home". Best 73 Alan
[AMRadio] Amplifier to use with my DX-60
I would like to use a cheap am with my DX-60. An SB-200-230 seems to be a Class B amp. There for it only conducts on the positive going cycle. I don't mean to sound silly, but someone told me I could run this in SSB Mode using AM input from my DX-60, I run 100 Watts carrier for 400 Watts peak, now that makes sense. What does not make sense is how do I get the other side of the wave form The Tank??? I guess the tank. I really need to go cheap on this project. I know, you guys will probably say "go big or go home". Best 73 Alan
