Re: [AMRadio] Smoothing Choke
Don and others... Thanks for all the information on chokes, capacitors and power supply schemes. They have all helped me tremendously in deciding which way to go and what to use to get the best bang for the buck out of the supply for the ART-13 transmitter. Just about the time I had my mind made up someone else would drop by with another great suggestion or real world advice. This is a great list with a bunch of well read participants. 73, Rick/K5IZ This is called the dynamic regulation. When keying a transmitter on cw, or running a class-B modulator or SSB linear, the plate (kilo)voltmeter may show little variation, indicating good regulation. But if you set up an oscilloscope to display the instantaseous power supply voltage, you may be surprised how much the voltage kicks around with the transients. The voltage not only dips down after the load is applied; when the load is removed the voltage will kick back upwards, and the momentum may swing it well above the nominal output voltage. I have seen power supplies where the voltage dropped below 70% nominal volatge and back up to 140% nominal or higher - a 2 to 1 voltage variation while the sluggish mechanical movement in the analogue voltmeter just barely wiggled with keying or modulation. Monitoring the cw output from a transmitter using a modulation monitor scope may show a horrible keyed waveform. The solution that has worked for me is to use as much capacitance in the output side of the filter as possible, without kicking the overload relay when the power supply is first turned on. I prefer to kill the HV during receive. Don't like having the full HV turned on while the transmitter is in standby - a death trap plus rf noise generator, and it hastens breakdown of HV components. You can use step-start if you want to further increase the capacitance, but I prefer to avoid that complication. Of course, increasing the inductance of the choke will reduce the inrush current to the capacitor by slowing down its charging rate. I converted my Gates BC1-T to CW capability, and was able to get a reasonable looking waveform by increasing the capacitance in the one-section choke input filter from 8 mfd to 25 mfd. It is still not perfect, but is satisfactory. My homebrew transmitter uses about the same capacitance each in the rf final plate supply and modulator plate supply. I have found that with a 2-2.5 kv power supply with a load not exceeding 700-800 mills total, a 25 mfd 4 kv output capacitor is about the best compromise between dynamic regulation and inrush current. With AM, the best solution is to use a common power supply for the modulator and final. The rf final acts like a heavy bleeder resistor, and maintains good dynamic regulation for the class-B modulator plates. Poor dynamic regulation can result in poor sounding audio, even though every component in the modulator is of the highest quality and the circuit is of the best design. If you are having an inexplicable audio quality problem, take a look at your HV power supply output voltage on an oscilloscope, to see what the dynamic regulation looks like. Connect up a series string of resistors, so that the total resistance is several times the normal bleeder resistance, and connect the vertical plates of the scope across the bottom resistor. Make sure the wattage and voltage rating of the resistors is not exceeded. Another way would be to temporarily disconnect the bottom end of the normal bleeder resistor, and insert a resistor of approximately 5% of the bleeder resistance in series with the bottom side. Place the scope probes between the connection between this resistor and the bleeder, and ground, to read the voltage across this resistor. If the resistor is 5% of the total resistance, 5% of the total voltage will appear across it. Thus, with a 2kv power supply, 100 volts will appear across the resistor, which is much easier to measure with a scope than the full 2000. Don k4kyv
RE: [AMRadio] Smoothing Choke
Sorry but I am going to throw a wrench into this discussion. Those swinging choke power supplies, although useful, have been out of favor for years, especially when the loading is transient such as for a CW rig. Sure if the critical inductance versus minimum load current are correct, the output voltage will not soar under a light or no load. But what happens when the load is applied suddenly such as with CW? The answer is arguable of course, but I think the answer is a sudden significant and momentary dip in B+ which all depends on the L-C-L-C values chosen. This is called the dynamic regulation. When keying a transmitter on cw, or running a class-B modulator or SSB linear, the plate (kilo)voltmeter may show little variation, indicating good regulation. But if you set up an oscilloscope to display the instantaseous power supply voltage, you may be surprised how much the voltage kicks around with the transients. The voltage not only dips down after the load is applied; when the load is removed the voltage will kick back upwards, and the momentum may swing it well above the nominal output voltage. I have seen power supplies where the voltage dropped below 70% nominal volatge and back up to 140% nominal or higher - a 2 to 1 voltage variation while the sluggish mechanical movement in the analogue voltmeter just barely wiggled with keying or modulation. Monitoring the cw output from a transmitter using a modulation monitor scope may show a horrible keyed waveform. The solution that has worked for me is to use as much capacitance in the output side of the filter as possible, without kicking the overload relay when the power supply is first turned on. I prefer to kill the HV during receive. Don't like having the full HV turned on while the transmitter is in standby - a death trap plus rf noise generator, and it hastens breakdown of HV components. You can use step-start if you want to further increase the capacitance, but I prefer to avoid that complication. Of course, increasing the inductance of the choke will reduce the inrush current to the capacitor by slowing down its charging rate. I converted my Gates BC1-T to CW capability, and was able to get a reasonable looking waveform by increasing the capacitance in the one-section choke input filter from 8 mfd to 25 mfd. It is still not perfect, but is satisfactory. My homebrew transmitter uses about the same capacitance each in the rf final plate supply and modulator plate supply. I have found that with a 2-2.5 kv power supply with a load not exceeding 700-800 mills total, a 25 mfd 4 kv output capacitor is about the best compromise between dynamic regulation and inrush current. With AM, the best solution is to use a common power supply for the modulator and final. The rf final acts like a heavy bleeder resistor, and maintains good dynamic regulation for the class-B modulator plates. Poor dynamic regulation can result in poor sounding audio, even though every component in the modulator is of the highest quality and the circuit is of the best design. If you are having an inexplicable audio quality problem, take a look at your HV power supply output voltage on an oscilloscope, to see what the dynamic regulation looks like. Connect up a series string of resistors, so that the total resistance is several times the normal bleeder resistance, and connect the vertical plates of the scope across the bottom resistor. Make sure the wattage and voltage rating of the resistors is not exceeded. Another way would be to temporarily disconnect the bottom end of the normal bleeder resistor, and insert a resistor of approximately 5% of the bleeder resistance in series with the bottom side. Place the scope probes between the connection between this resistor and the bleeder, and ground, to read the voltage across this resistor. If the resistor is 5% of the total resistance, 5% of the total voltage will appear across it. Thus, with a 2kv power supply, 100 volts will appear across the resistor, which is much easier to measure with a scope than the full 2000. 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] Smoothing Choke & RX filter audio resonance
Jim, You may have just provided me an answer to an issue I have with a BC779 ! de KA4JVY Mark --- Jim candela <[EMAIL PROTECTED]> wrote: > > Rick, > >I understand your feel for the nostalgia, and passion for pursuing it. > All of us more or less on this group have some common ground here. > > I'd like to relate a story however to make a point. I have an RCA AR-88 > receiver. This 'heavy' boat anchor has multiple chokes, and oil capacitors > in the 250 volt power supply. I don't recall the values, or whether the > first choke was swinging or not, but I do recall the problem. I started a > project to beef up the audio from the receiver. This included extending the > LF response to 50 HZ, and multiple negative feedback paths around the audio > output tube (6K6?). What happened really surprised me. The power available > below 300 hz steadily dropped off, but much steeper than I anticipated. It > turned out that I had over 50 volts P-P ripple on the B+ whenever I cranked > the audio up when listening to AM broadcast 'male' voices. I looked at the > B+ on a scope, and I'll never forget what I saw. The waveform was going up, > and down with the audio, and sometimes exploding in amplitude when a certain > audio pitch was being sent to my loudspeaker. It was kind of like a > automobile driving over speed bumps, and not having any shock absorbers! > > The problem was filter resonance excited by the audio rate draw by the audio > output tube. In the end, a single 100 uf 450V capacitor across the B+ cured > the problem, and I had nice clean bass down to 50 hz as desired. > > As far as resonating a smoothing choke, this is not new stuff, so you might > keep that option on the table. At the following link I have an example of > where I did this with good success. The supply was already choke input, but > the critical inductance was not met, so the regulation was poor, and the > ripple was higher than I wanted. By simply resonating the choke, both > problems were solved. Here is the link: > > http://pages.prodigy.net/jcandela/CE20AQRO/PS.JPG > > Regards, > Jim > JKO > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf Of Rick Brashear > Sent: Thursday, May 04, 2006 9:58 AM > To: Discussion of AM Radio > Subject: Re: [AMRadio] Smoothing Choke > > > Jim, > I appreciate your take on the power supply and agree for the most > part. Even though this particular ART-13 will see little if any CW > operation I would like the supply to be as stable and clean as > reasonably possible. You are absolutely correct about the difference of > availability of capacitors and chokes in today's world versus the days > of W.W.II. I considered using more modern components and at one time > even thought about an all solid state power supply. It would be much > easier and cheaper to construct and less expensive to operate with less > heat. However, the lure of the olden days kept calling me back to > glowing tubes and swinging chokes. So, even though I agree that with > modern technology applied I could have a cleaner, lighter and less > expensive supply, I will likely stay with the old school thinking on > this one. That is IF I can get the ripple to a low enough level so as > not to cause problems on the transmitted signal. > Thanks again for your advice and explanation, you make a very valid > point and one which would serve my project well. > 73, > Rick/K5IZ > > > > Jim candela wrote: > > >Rick, > > > > Sorry but I am going to throw a wrench into this discussion. Those > >swinging choke power supplies, although useful, have been out of favor for > >years... > > > > > > > > > __ > 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: 268.5.2/329 - Release Date: 5/2/2006 > > -- > No virus found in this outgoing message. > Checked by AVG Free Edition. > Version: 7.1.385 / Virus Database: 268.5.2/329 - Release Date: 5/2/2006 > > __ > 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 > __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
Re: [AMRadio] Smoothing Choke & ART-13 supplies
Group, This discussion re the power supply filter has got me thinking. This stuff has been done both ways. I have built a power supply for my TBW using the swinging / smoothing choke arrangements. However, I also have in operation a 115 vac power supply for the ART-13. It was made by the R.L. Drake Company - yup, the same one that is (was) in Miamisburg. Oddly enough, it is not that heavy. Perhaps 40 lbs. When I got the unit the filament supply transformer was dead. I replaced the (4) 866jr with silicon, all the electrolytics have been replaced and I reworked the filament supply. I removed the giant selenium rectifier in lieu of a full bridge rectifier that was now mounted to the chassis. I placed some large computer grade 35 volt cap across the output. The filament transformer was replaced by a 19 volt 30 or so amp transformer ( 19 X 1.41 = 26.79 volts - close enough. ) The filter for both the hv supplies is a choke input followed by the electrolytic. Presumably, it is pure smoothing. The only thing I did to the ART-13 was remove autotune functionality by desoldering a field winding. Apparently, the fields are energized the entire time filament was supplied making for a warm front panel and unnecessary load on the power supply. By the way, I understand there is a mod to get around this "continuous field on" situation besides my approach of desoldering the field connection. If anyone has the dope on that pleas let me know. de KA4JVY Mark --- Rick Brashear <[EMAIL PROTECTED]> wrote: > Jim, > I appreciate your take on the power supply and agree for the most > part. Even though this particular ART-13 will see little if any CW > operation I would like the supply to be as stable and clean as > reasonably possible. You are absolutely correct about the difference of > availability of capacitors and chokes in today's world versus the days > of W.W.II. I considered using more modern components and at one time > even thought about an all solid state power supply. It would be much > easier and cheaper to construct and less expensive to operate with less > heat. However, the lure of the olden days kept calling me back to > glowing tubes and swinging chokes. So, even though I agree that with > modern technology applied I could have a cleaner, lighter and less > expensive supply, I will likely stay with the old school thinking on > this one. That is IF I can get the ripple to a low enough level so as > not to cause problems on the transmitted signal. > Thanks again for your advice and explanation, you make a very valid > point and one which would serve my project well. > 73, > Rick/K5IZ > > > > Jim candela wrote: > > >Rick, > > > > Sorry but I am going to throw a wrench into this discussion. Those > >swinging choke power supplies, although useful, have been out of favor for > >years... > > > > > > > > > __ > 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 > __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
Re: [AMRadio] Smoothing Choke
Let me clear my perfectly description make! Collins: 10 hy 10 hy Rectifier --choke---choke|HV out |---cap---| | 0.08uf cap 8 uf | /// Larry Taft wrote: Typical values for a Gates BC-1G 1 KW broadcast transmitter 2500 VDC supply are 5-15 hy at 1 amp swinging choke with 8 uf filter cap. The load is 500 ma continuous for the class C final ( 2 833s in parallel) plus another 500 ma variable for the class B modulator ( 2 833s in push-pull). The audio frequency response is speced at 30 to 12,000 cycles per second. The broadcast people used a single supply with the final acting as a fixed minimum load to get around the filter resonance problem at low frequencies. Collins also used a cap across a choke for parallel resonance. For the 20V3 there is a 10 hy choke with a 0.08 uf cap across it in parallel to a second 10 hy choke (no cap) to an 8 uf cap to ground. Again, the final is a fixed load for the single supply. Tubes are 4-400s. Audio speced at 50 to 10,000 cycles per second. Old technology. Still good as long as the limits are understood. Larry K2LT Jim candela wrote: Rick, I understand your feel for the nostalgia, and passion for pursuing it. All of us more or less on this group have some common ground here. __ 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] Smoothing Choke
Typical values for a Gates BC-1G 1 KW broadcast transmitter 2500 VDC supply are 5-15 hy at 1 amp swinging choke with 8 uf filter cap. The load is 500 ma continuous for the class C final ( 2 833s in parallel) plus another 500 ma variable for the class B modulator ( 2 833s in push-pull). The audio frequency response is speced at 30 to 12,000 cycles per second. The broadcast people used a single supply with the final acting as a fixed minimum load to get around the filter resonance problem at low frequencies. Collins also used a cap across a choke for parallel resonance. For the 20V3 there is a 10 hy choke with a 0.08 uf cap across it in parallel to a second 10 hy choke (no cap) to an 8 uf cap to ground. Again, the final is a fixed load for the single supply. Tubes are 4-400s. Audio speced at 50 to 10,000 cycles per second. Old technology. Still good as long as the limits are understood. Larry K2LT Jim candela wrote: Rick, I understand your feel for the nostalgia, and passion for pursuing it. All of us more or less on this group have some common ground here.
Re: [AMRadio] Smoothing Choke
Jim, That is very interesting and I may very well have to incorporate such a scheme to achieve my needs. Needless to say, I want the cleanest and most stable source I can get. These old gals certainly weren't made with fidelity in mind and that is one aspect on which I'd like to improve, so it may be that I'll need to employ your tactics. I appreciate your comments, link and time. Hopefully, using a little of the new in with the old will satisfy my desire to keep it true to the period and have a good sounding signal to boot. 73 , Rick/K5IZ Jim candela wrote: Rick, I understand your feel for the nostalgia, and passion for pursuing it. All of us more or less on this group have some common ground here. I'd like to relate a story however to make a point. I have an RCA AR-88 receiver. This 'heavy' boat anchor has multiple chokes, and oil capacitors in the 250 volt power supply. I don't recall the values, or whether the first choke was swinging or not, but I do recall the problem. I started a project to beef up the audio from the receiver. This included extending the LF response to 50 HZ, and multiple negative feedback paths around the audio output tube (6K6?). What happened really surprised me. The power available below 300 hz steadily dropped off, but much steeper than I anticipated. It turned out that I had over 50 volts P-P ripple on the B+ whenever I cranked the audio up when listening to AM broadcast 'male' voices. I looked at the B+ on a scope, and I'll never forget what I saw. The waveform was going up, and down with the audio, and sometimes exploding in amplitude when a certain audio pitch was being sent to my loudspeaker. It was kind of like a automobile driving over speed bumps, and not having any shock absorbers! The problem was filter resonance excited by the audio rate draw by the audio output tube. In the end, a single 100 uf 450V capacitor across the B+ cured the problem, and I had nice clean bass down to 50 hz as desired. As far as resonating a smoothing choke, this is not new stuff, so you might keep that option on the table. At the following link I have an example of where I did this with good success. The supply was already choke input, but the critical inductance was not met, so the regulation was poor, and the ripple was higher than I wanted. By simply resonating the choke, both problems were solved. Here is the link: http://pages.prodigy.net/jcandela/CE20AQRO/PS.JPG Regards, Jim JKO
RE: [AMRadio] Smoothing Choke
Rick, I understand your feel for the nostalgia, and passion for pursuing it. All of us more or less on this group have some common ground here. I'd like to relate a story however to make a point. I have an RCA AR-88 receiver. This 'heavy' boat anchor has multiple chokes, and oil capacitors in the 250 volt power supply. I don't recall the values, or whether the first choke was swinging or not, but I do recall the problem. I started a project to beef up the audio from the receiver. This included extending the LF response to 50 HZ, and multiple negative feedback paths around the audio output tube (6K6?). What happened really surprised me. The power available below 300 hz steadily dropped off, but much steeper than I anticipated. It turned out that I had over 50 volts P-P ripple on the B+ whenever I cranked the audio up when listening to AM broadcast 'male' voices. I looked at the B+ on a scope, and I'll never forget what I saw. The waveform was going up, and down with the audio, and sometimes exploding in amplitude when a certain audio pitch was being sent to my loudspeaker. It was kind of like a automobile driving over speed bumps, and not having any shock absorbers! The problem was filter resonance excited by the audio rate draw by the audio output tube. In the end, a single 100 uf 450V capacitor across the B+ cured the problem, and I had nice clean bass down to 50 hz as desired. As far as resonating a smoothing choke, this is not new stuff, so you might keep that option on the table. At the following link I have an example of where I did this with good success. The supply was already choke input, but the critical inductance was not met, so the regulation was poor, and the ripple was higher than I wanted. By simply resonating the choke, both problems were solved. Here is the link: http://pages.prodigy.net/jcandela/CE20AQRO/PS.JPG Regards, Jim JKO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Rick Brashear Sent: Thursday, May 04, 2006 9:58 AM To: Discussion of AM Radio Subject: Re: [AMRadio] Smoothing Choke Jim, I appreciate your take on the power supply and agree for the most part. Even though this particular ART-13 will see little if any CW operation I would like the supply to be as stable and clean as reasonably possible. You are absolutely correct about the difference of availability of capacitors and chokes in today's world versus the days of W.W.II. I considered using more modern components and at one time even thought about an all solid state power supply. It would be much easier and cheaper to construct and less expensive to operate with less heat. However, the lure of the olden days kept calling me back to glowing tubes and swinging chokes. So, even though I agree that with modern technology applied I could have a cleaner, lighter and less expensive supply, I will likely stay with the old school thinking on this one. That is IF I can get the ripple to a low enough level so as not to cause problems on the transmitted signal. Thanks again for your advice and explanation, you make a very valid point and one which would serve my project well. 73, Rick/K5IZ Jim candela wrote: >Rick, > > Sorry but I am going to throw a wrench into this discussion. Those >swinging choke power supplies, although useful, have been out of favor for >years... > > > __ 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: 268.5.2/329 - Release Date: 5/2/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.5.2/329 - Release Date: 5/2/2006
Re: [AMRadio] Smoothing Choke
Jim, I appreciate your take on the power supply and agree for the most part. Even though this particular ART-13 will see little if any CW operation I would like the supply to be as stable and clean as reasonably possible. You are absolutely correct about the difference of availability of capacitors and chokes in today's world versus the days of W.W.II. I considered using more modern components and at one time even thought about an all solid state power supply. It would be much easier and cheaper to construct and less expensive to operate with less heat. However, the lure of the olden days kept calling me back to glowing tubes and swinging chokes. So, even though I agree that with modern technology applied I could have a cleaner, lighter and less expensive supply, I will likely stay with the old school thinking on this one. That is IF I can get the ripple to a low enough level so as not to cause problems on the transmitted signal. Thanks again for your advice and explanation, you make a very valid point and one which would serve my project well. 73, Rick/K5IZ Jim candela wrote: Rick, Sorry but I am going to throw a wrench into this discussion. Those swinging choke power supplies, although useful, have been out of favor for years...
RE: [AMRadio] Smoothing Choke
Rick, Sorry but I am going to throw a wrench into this discussion. Those swinging choke power supplies, although useful, have been out of favor for years, especially when the loading is transient such as for a CW rig. Sure if the critical inductance versus minimum load current are correct, the output voltage will not soar under a light or no load. But what happens when the load is applied suddenly such as with CW? The answer is arguable of course, but I think the answer is a sudden significant and momentary dip in B+ which all depends on the L-C-L-C values chosen. My choice in situations like this is to use choke input with a smoothing choke (not swinging), and resonate the choke at the ripple frequency (say 100 or 120 hz) with a suitable oil filled parallel capacitor, and then use a large value capacitor from output B+ to ground. With today's inexpensive "snap-in" electrolytics, we can easily have significant energy storage in the output filter capacitor. Back when those old handbooks were written, chokes were easy to make, and capacitor technology was difficult to get high 'C' in a small area for low cost. Today capacitors are dirt cheap, and the prices of chokes are sky high. Aiming for no more than 1% full load ripple is doable with today's components, and without high cost. If the turn on transients are too high for your rectifiers, maybe consider a two step start circuit to limit peak current surge, and then apply full voltage to the primary. This can often be done with a relay and a few other parts. For audio use, whether for low level audio, modulator B+, or unmodulated B+ to the final PA, the supplies must be bypassed well (low reactance) at the lowest audio frequency used. If not the power supplies themselves will get modulated progressively worse as the audio frequency drops. This leads to all kinds of instabilities such as unwanted feedback, or maybe "motor-boating". Vintage supplies were often notorious for being modulated unless the audio frequency was limited to something no lower than the power line ripple frequency that the filter was designed for. Can those in this group with ex-broadcast transmitters such as the 20V2 describe what types of filters these transmitters use? Regards, Jim JKO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Rick Brashear Sent: Wednesday, May 03, 2006 8:06 PM To: [EMAIL PROTECTED]; Discussion of AM Radio Subject: Re: [AMRadio] Smoothing Choke Let me be sure I am correct in my calculations. Choke input (5 - 25 H) with 4 mfd filter will allow about 5% ripple. Now, when I add the second choke (5.5 H) and the second filter (2 mfd) is this now calculated as a capacitor input for this last stage? If so, then it would result in another .15% reduction or about 3.3% total ripple. Is this correct? Rick Brian Carling wrote: >Yipes - 5% ripple on a 400V supply - won't that give you about >20V of AC buzz on your carrier? > > > __ 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: 268.5.2/329 - Release Date: 5/2/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.5.2/329 - Release Date: 5/2/2006
Re: [AMRadio] Smoothing Choke
I've heard others telling similar stories, so I hope I am going heavy enough. I have an old ferroresonant transformer for the low voltage supply that runs hot anyway, but is capable of at least 50 amps, so it should do fine. My problem with this supply is I ain't no spring chicken anymore and this dude is getting heavy! Rick Brian Carling wrote: Thoise autotune motors draw a LOT of current. I built a power supply with an 8 Amp transformer from FAIR RADIO for mine back in the 1980s. MAN that transformer ran HOT,... even with no load!
Re: [AMRadio] Smoothing Choke
Thoise autotune motors draw a LOT of current. I built a power supply with an 8 Amp transformer from FAIR RADIO for mine back in the 1980s. MAN that transformer ran HOT,... even with no load! > From what I understand the filaments and auto tune on the ART-13 > transmitter require about 10 amps. It's gonna be a big supply when I'm > through, no doubt. > > Rick > > W5OMR/Geoff wrote: > > > > > > > 27v * 10amps = 270w. You got something that's gonna be pulling that > > much current? > > > > -- > > 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] Smoothing Choke
W5OMR/Geoff wrote: 27v * 10amps = 270w. You got something that's gonna be pulling that much current? Rick Brashear wrote: From what I understand the filaments and auto tune on the ART-13 transmitter require about 10 amps. It's gonna be a big supply when I'm through, no doubt. Silly me - ART-13. Never mind :-) -- 73 = Best Regards, -Geoff/W5OMR A: Yes. > Q: Are you sure? >> A: Because it reverses the logical flow of conversation. >>> Q: Why is top posting annoying in email?
Re: [AMRadio] Smoothing Choke
From what I understand the filaments and auto tune on the ART-13 transmitter require about 10 amps. It's gonna be a big supply when I'm through, no doubt. Rick W5OMR/Geoff wrote: 27v * 10amps = 270w. You got something that's gonna be pulling that much current? -- Geoff/W5OMR
Re: [AMRadio] Smoothing Choke
W5OMR/Geoff wrote: 10 *Amps*? You mean 10 Henry, at about a half an amp, right? Rick Brashear wrote: I think I need about a 10 mH @ 10 amp choke for the 27 volt supply. Of course, I could be calculating wrong. 27v * 10amps = 270w. You got something that's gonna be pulling that much current? -- Geoff/W5OMR
Re: [AMRadio] Smoothing Choke
I think I need about a 10 mH @ 10 amp choke for the 27 volt supply. Of course, I could be calculating wrong. Rick W5OMR/Geoff wrote: 10 *Amps*? You mean 10 Henry, at about a half an amp, right? -- 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] Smoothing Choke
Let me be sure I am correct in my calculations. Choke input (5 - 25 H) with 4 mfd filter will allow about 5% ripple. Now, when I add the second choke (5.5 H) and the second filter (2 mfd) is this now calculated as a capacitor input for this last stage? If so, then it would result in another .15% reduction or about 3.3% total ripple. Is this correct? Rick Brian Carling wrote: Yipes - 5% ripple on a 400V supply - won't that give you about 20V of AC buzz on your carrier?
Re: [AMRadio] Smoothing Choke
Rick Brashear wrote: Thanks Jim and all who replied. I'll check one of my older Handbooks and see if I can match up the choke with suitable capacitors to get the ripple as low as possible. I'm also going to need a 10 amp choke for the low voltage supply. 10 *Amps*? You mean 10 Henry, at about a half an amp, right? -- 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] Smoothing Choke
> If you use 4 uf. and 5 H with choke input, it says the ripple percent will > approximate 4%. Usually 5% is where most people go since it takes such > large values to exceed that. Yipes - 5% ripple on a 400V supply - won't that give you about 20V of AC buzz on your carrier?
Re: [AMRadio] Smoothing Choke
Thanks Jim and all who replied. I'll check one of my older Handbooks and see if I can match up the choke with suitable capacitors to get the ripple as low as possible. If anyone has a 5 - 25 swinging choke they'd be interested in dealing I am in need of another one. I'm also going to need a 10 amp choke for the low voltage supply. Thanks to all Rick/K5IZ Jim Wilhite wrote: Rick pick up and old ARRL handbook. I have a 56 year version and it has charts that will help you determine the percent of ripple with various combinations of L and C. If you use 4 uf. and 5 H with choke input, it says the ripple percent will approximate 4%. Usually 5% is where most people go since it takes such large values to exceed that. 73 Jim W5JO Hi: I am finally building the power supply for my ART-13 transmitter and would like your opinion on a thing or two. Thanks to Ronnie Hull, I have a 5 - 25 henry swinging choke for the HV supply. I also have, thanks to an old TX-1, a 400 ma smoothing choke, 5.5 henry @ 400 ma. I wanted to use something a little larger, maybe 10 or 12 henry. I'm using 866 or maybe 3B28 rectifiers and 4 mfd and 8 mfd filters. Do you think the 5.5 henry choke will be sufficient? I also need another 5 - 25 swinging choke in the 250 ma range for the 400 volt supply. It too will use another 5.5 henry choke if it is determined that is sufficient. Any and all advice, opinions, criticism or comments are welcome. Thanks, Rick/K5IZ __ 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] Smoothing Choke
Rick pick up and old ARRL handbook. I have a 56 year version and it has charts that will help you determine the percent of ripple with various combinations of L and C. If you use 4 uf. and 5 H with choke input, it says the ripple percent will approximate 4%. Usually 5% is where most people go since it takes such large values to exceed that. 73 Jim W5JO Hi: I am finally building the power supply for my ART-13 transmitter and would like your opinion on a thing or two. Thanks to Ronnie Hull, I have a 5 - 25 henry swinging choke for the HV supply. I also have, thanks to an old TX-1, a 400 ma smoothing choke, 5.5 henry @ 400 ma. I wanted to use something a little larger, maybe 10 or 12 henry. I'm using 866 or maybe 3B28 rectifiers and 4 mfd and 8 mfd filters. Do you think the 5.5 henry choke will be sufficient? I also need another 5 - 25 swinging choke in the 250 ma range for the 400 volt supply. It too will use another 5.5 henry choke if it is determined that is sufficient. Any and all advice, opinions, criticism or comments are welcome. Thanks, Rick/K5IZ
Re: [AMRadio] Smoothing Choke
Rick, IN my AN/ART-13, I'm using a 4H .25 amp choke in my B+.. no problem. It consists of (2) 10uF 2kv oil cans with the choke in the negative lead (upside down pie, along with 100K bleaders). No problems so far .. any questions, feel free klc - Original Message - From: Rick Brashear <[EMAIL PROTECTED]> Date: Wednesday, May 3, 2006 4:22 pm Subject: [AMRadio] Smoothing Choke To: Discussion of AM Radio > Hi: > I am finally building the power supply for my ART-13 transmitter > and > would like your opinion on a thing or two. Thanks to Ronnie Hull, > I > have a 5 - 25 henry swinging choke for the HV supply. I also > have, > thanks to an old TX-1, a 400 ma smoothing choke, 5.5 henry @ 400 > ma. I > wanted to use something a little larger, maybe 10 or 12 henry. > I'm > using 866 or maybe 3B28 rectifiers and 4 mfd and 8 mfd filters. > Do you > think the 5.5 henry choke will be sufficient? > > I also need another 5 - 25 swinging choke in the 250 ma range for > the > 400 volt supply. It too will use another 5.5 henry choke if it is > determined that is sufficient. > > Any and all advice, opinions, criticism or comments are welcome. > > Thanks, > Rick/K5IZ > > > __ > 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] Smoothing Choke
Hi: I am finally building the power supply for my ART-13 transmitter and would like your opinion on a thing or two. Thanks to Ronnie Hull, I have a 5 - 25 henry swinging choke for the HV supply. I also have, thanks to an old TX-1, a 400 ma smoothing choke, 5.5 henry @ 400 ma. I wanted to use something a little larger, maybe 10 or 12 henry. I'm using 866 or maybe 3B28 rectifiers and 4 mfd and 8 mfd filters. Do you think the 5.5 henry choke will be sufficient? I also need another 5 - 25 swinging choke in the 250 ma range for the 400 volt supply. It too will use another 5.5 henry choke if it is determined that is sufficient. Any and all advice, opinions, criticism or comments are welcome. Thanks, Rick/K5IZ
