Re: [AMRadio] RE: negative cycle loading
In a message dated 4/5/04 1:46:46 PM, [EMAIL PROTECTED] writes: > Since the circuit works as far as the mod monitor indicates, > there must be something very fast making it through the circuit. > If I could just find a way to eliminate the short spikes > of over 100% negative making it through, it would work great. > > Brett, If very short spikes are being generated in the NCL circuit somehow, they wouldn't necessarily have to be modulating the PA more than 100% negative to produce splatter. If high amplitude, such could contain enough high frequency components on their own to produce way-out sidebands. Have never run into this, though, in my experience with NCL circuits. Dennis D. W7QHO Glendale, CA --- StripMime Report -- processed MIME parts --- multipart/alternative text/plain (text body -- kept) text/html The reason this message is shown is because the post was in HTML or had an attachment. Attachments are not allowed. To learn how to post in Plain-Text go to: http://www.expita.com/nomime.html ---
Re: [AMRadio] RE: negative cycle loading
Brett, Sounds to me like you're hard clipping the negative peaks, either in your negative loading setup and/or by driving the PA down below zero.Hard to be definitive here, though, not knowing exactly what circuit you're using. The "three diode" circuit I'm familiar with doesn't use an additional power supply (see http://www.amwindow.org/tech/htm/3diode.htm). If adjusted properly, this circuit will allow modulation percentages in excess of 100 on positive peaks without overmodulation (i.e., more that 100%) in the negative direction. Does distort the speech waveform to be sure but does not produce spurious products out 30 kHz or more. It's also possible to misadjust this circuit to splatter like hell. Dennis D. W7QHO Glendale, CA > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Brett Gazdzinski > Sent: Sunday, April 04, 2004 10:51 PM > To: amradio@mailman.qth.net > Subject: [AMRadio] RE: negative cycle loading > > > Hello all AM,ers. > I was running the new 4d32 rf deck on the air over the weekend, and > it works very well. > I 'stole' the 811a modulator from the 812a rig to modulate > the 4d32 rig till I get the kt90 mod deck built. > After many and various tests of different voltage and currents on the > plates > and screens, etc, it seems to like running at 1100 volts and 300ma, for > about > 220 watts out, although I can get 300 watts out. > It modulates well, up to 900 watts pep. > But my negative cycle loading setup seems to introduce spurs out the > sides > when it comes into play. > I looked at it on the spectrum analyzer. > I use the 3 diode, resistor, and separate power supply that sets the > negative > percentage (using a variac). > > I once talked with someone on the air about this circuit, and they told > me > it had a design flaw, and needed something, another diode, resistor, or > something, but I cant remember what they said, or who said it. > > I use the 1 amp 14,000 volt diode bricks in the circuit, and maybe > something to do with switching speeds, bias, or something, but when I > invoke > the circuit, I get big spurs out the sides, out to 30kc each side 40 > db down. > The mod monitor says the modulation is getting limited to 90% > or whatever I set it to, but running it is even worse than over > modulating. > I use this circuit in a number of rigs with the same results. > > The audio is clean, and I even added some resistors to the plates of the > 811a > mod tubes, grids are swamped, adjusting the various voltages and > drives on the 4d32 rig has zero effect on the spurs. > > Sure would like to get the circuit to work well, as I can run the audio > up much more and load the negative spikes. > I don't want to run into it heavy, just trim some peaks off the negative > side. > > Thanks for any info, > Brett > N2DTS > > > --- StripMime Report -- processed MIME parts --- multipart/alternative text/plain (text body -- kept) text/html The reason this message is shown is because the post was in HTML or had an attachment. Attachments are not allowed. To learn how to post in Plain-Text go to: http://www.expita.com/nomime.html ---
[AMRadio] Collins Collectors Association First Wednesday AM Night April 7th
FIRST WEDNESDAY AM NIGHT !!! Sponsored by the Collins Collectors Association. Cedar Rapids, Iowa (QRZ) - Wednesday April 7th on 3880 kcs at 7:30PM local East Coast time marks the start of the latest chapter of First Wednesday AM Night, drawing hundreds of vintage stations from across the country. The event is anchored by a "tall ship" AM station in each time zone. The East Coast will run for 90 minutes this month as a test. The remaining time zones will be an hour. Stations check-in using Collins and other transmitters with AM capabilities, new and old. The idea is to revel in this nostalgic mode, enjoy giving vintage equipment a "run," and sharing some storytelling about classic vacuum tube homebrew and commercial designs. In months past, anchor stations have included those running the beautiful Collins 300-G, pictured below, as well as those running the amateur KW-1 and other noted models. http://www.amwindow.org/pix/jpg/300g.jpg LISTEN for these anchors and stop by to say hello, won't you? You don't have to be running Collins or vintage gear to be welcomed into the group. 7:30P-9P East Coast Anchor: Bill K2LNU (upstate NY) 8P-9P Midwest Anchor: Tony W9JXN (Illinois) 8P-9P Rocky Mountain Anchor: Jim WA0LSB (Colorado) 8P-9P West Coast Anchor: Bill, N6PY (California) comments please to [EMAIL PROTECTED]
RE: [AMRadio] negative cycle loading
Sounds like the old Ultramodulation circuit, that first appeared in QST in 1956. I tried it years ago (using 866A's and 200-watt power resistors) but about the only thing it increased on the receiving end was distortion. Listeners told me the audio didn't sound any louder or more intelligible, but had a raspy quality. The DC plate meter kicked upwards on modulation peaks, and the rf ammeter kicked higher than with normal modulation, but much of the kick is due to rectified audio being added to the DC from the power supply. Audio power is too expensive and difficult to generate, to waste in a power resistor, or convert to DC to boost carrier output on modulation peaks. There are other, more economical means of generating "controlled carrier" (which I don't recommend in any case). I would recommend a good broadcast type peak limiter with separately adjustable positive and negative peaks, or a clipper circuit adjusted to shave off only the infrequent, abnormally high amplitude negative peaks. Be sure that everything that follows the clipper or limiter has excellent low frequency response. If you are looking for extended positive peaks, the best way to achieve that is to take advantage of the natural asymmetry of the human voice. Use a good microphone, the best audio transformers you can find, and design the audio chain to have a flat frequency response at least one octave above and below the high and low frequency extremes you actually intend to transmit. Make sure distortion in the audio chain (both phase and intermod) are as low as you can make them. Use a low-level audio filter or equaliser near the mic preamp for any frequency response shaping. Low-value coupling capacitors and other response-shaping gizmos inserted throughout the audio chain will introduce phase shift distortion that will destroy the asymmetrical peaks. Don K4KYV _ Free up your inbox with MSN Hotmail Extra Storage! Multiple plans available. http://join.msn.com/?pgmarket=en-us&page=hotmail/es2&ST=1/go/onm00200362ave/direct/01/
Re: [AMRadio] FS: B&W 5100-B, DX-100, Tubes
I would be interested in the 6146s tell me where to send the postage. W5JAI Merz Donald S wrote: FOR SALE. Headed for eBay unless someone here wants this stuff. B&W 5100B HF AM/CW transmitter. Looks all original and complete. No holes, no rust, original knobs, paint, meter and dial. Dial works. Silk screening is crisp and clear. Has paint chips all around turned edge of front panel. Cabinet has one paint chip on top but is otherwise quite excellent. Clean inside. Good candidate for restoration. Untested. As-is. $259 Heathkit DX-100 HF CW/AM transmitter in the large gray case. This version looks just like all the others, but it has a lift-up lid on top. Could that be original? All original knobs, meter, paint and dial except small red concentric knobs are missing (like they all are--what a bad design those were!). Front panel and case have some marks but both look very good. Needs a cleaning but should restore to excellent condition. Untested. As-is. $165 Another Heathkit DX-100--this one for parts. Heavily modified with unoriginal holes and controls on the front panel. The original large gray cabinet has been painted sloppy black. Missing some knobs including main tuning and missing tubes including 1625s. Inside is incredibly dirty and probably has some corrosion underneath. Untested. As-is. Parts unit. $60 x99 tubes. I have 8 199, 299 and other x99 tubes that are ALL DUDS except one which appears gassy. Also in this group is an RCA 120 dud that looks just like the x99. Most of these are RCA or unlabeled. One has an original Songbird paper label on it. $20 PPD for all. Two 6GE5 compactron tubes as used in Heathkit single bander finals. Used pulls. Untested. $8/both PPD 3 12GE5 Compactron tubes possibly used as finals in some Heathkit gear. Used pulls. Untested. $9/all 3 PPD 6KD6 Compactron sweep final tube. Used pull. Untested. $5 PPD Motorola HEP 2 transistor band new in original retail sales package with documentation. Kind of worn looking. Tomorrow's collectible today. $10 PPD FREE: 4 6146B tubes with top caps that have come off. Repairable with some effort. Untested. Thanks for looking. 73, Don Merz, N3RHT The information contained in this e-mail may be confidential and is intended solely for the use of the named addressee. Access, copying or re-use of the e-mail or any information contained therein by any other person is not authorized. If you are not the intended recipient please notify us immediately by returning the e-mail to the originator.(A) ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
[AMRadio] FS: B&W 5100-B, DX-100, Tubes
FOR SALE. Headed for eBay unless someone here wants this stuff. B&W 5100B HF AM/CW transmitter. Looks all original and complete. No holes, no rust, original knobs, paint, meter and dial. Dial works. Silk screening is crisp and clear. Has paint chips all around turned edge of front panel. Cabinet has one paint chip on top but is otherwise quite excellent. Clean inside. Good candidate for restoration. Untested. As-is. $259 Heathkit DX-100 HF CW/AM transmitter in the large gray case. This version looks just like all the others, but it has a lift-up lid on top. Could that be original? All original knobs, meter, paint and dial except small red concentric knobs are missing (like they all are--what a bad design those were!). Front panel and case have some marks but both look very good. Needs a cleaning but should restore to excellent condition. Untested. As-is. $165 Another Heathkit DX-100--this one for parts. Heavily modified with unoriginal holes and controls on the front panel. The original large gray cabinet has been painted sloppy black. Missing some knobs including main tuning and missing tubes including 1625s. Inside is incredibly dirty and probably has some corrosion underneath. Untested. As-is. Parts unit. $60 x99 tubes. I have 8 199, 299 and other x99 tubes that are ALL DUDS except one which appears gassy. Also in this group is an RCA 120 dud that looks just like the x99. Most of these are RCA or unlabeled. One has an original Songbird paper label on it. $20 PPD for all. Two 6GE5 compactron tubes as used in Heathkit single bander finals. Used pulls. Untested. $8/both PPD 3 12GE5 Compactron tubes possibly used as finals in some Heathkit gear. Used pulls. Untested. $9/all 3 PPD 6KD6 Compactron sweep final tube. Used pull. Untested. $5 PPD Motorola HEP 2 transistor band new in original retail sales package with documentation. Kind of worn looking. Tomorrow's collectible today. $10 PPD FREE: 4 6146B tubes with top caps that have come off. Repairable with some effort. Untested. Thanks for looking. 73, Don Merz, N3RHT The information contained in this e-mail may be confidential and is intended solely for the use of the named addressee. Access, copying or re-use of the e-mail or any information contained therein by any other person is not authorized. If you are not the intended recipient please notify us immediately by returning the e-mail to the originator.(A)
RE: [AMRadio] RE: negative cycle loading
John, Yes, I am well aware of the stuff in the link you posted. The problem is, the NCL circuit SHOULD work well, but does not. Maybe its the voltage drop through the high voltage bricks, or rather the voltage it takes for them to conduct. On the bricks, its volts, maybe as high as 5 volts before they conduct. Or maybe they are just too slow for higher frequency audio stuff. Since the circuit works as far as the mod monitor indicates, there must be something very fast making it through the circuit. If I could just find a way to eliminate the short spikes of over 100% negative making it through, it would work great. My voice does not show a huge difference between positive and negative, maybe 10%? I suppose a low level method would work best, but like the idea of a circuit in the RF deck that prevents negative overmod no matter what I do. Looking at the circuit, maybe I will try some things, like returning the load resistor to ground instead of the power supply, putting a cap across some of the diodes to smooth things, etc. Brett N2DTS > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf Of John Coleman, ARS > WA5BXO > Sent: Monday, April 05, 2004 8:43 AM > To: amradio@mailman.qth.net > Subject: RE: [AMRadio] RE: negative cycle loading > > > Hi Bret: > Many of us have played with neg cycle loading to find the same > thing that you have found. You would need a low pass filter after the > limiting circuit but these things make the audio have > resonate peaks and > limited freq response. (poor sounding) > If you have good freq response in the lows then your audio will > probably be lopsided anyway, especially if you talk close to the mic. > > SEE - http://www.qsl.net/wa5bxo/asyam/aam3.html > > Good luck, > John, WA5BXO > > > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Brett Gazdzinski > Sent: Sunday, April 04, 2004 10:51 PM > To: amradio@mailman.qth.net > Subject: [AMRadio] RE: negative cycle loading > > > Hello all AM,ers. > I was running the new 4d32 rf deck on the air over the weekend, and > it works very well. > I 'stole' the 811a modulator from the 812a rig to modulate > the 4d32 rig till I get the kt90 mod deck built. > After many and various tests of different voltage and currents on the > plates > and screens, etc, it seems to like running at 1100 volts and > 300ma, for > about > 220 watts out, although I can get 300 watts out. > It modulates well, up to 900 watts pep. > But my negative cycle loading setup seems to introduce spurs out the > sides > when it comes into play. > I looked at it on the spectrum analyzer. > I use the 3 diode, resistor, and separate power supply that sets the > negative > percentage (using a variac). > > I once talked with someone on the air about this circuit, and > they told > me > it had a design flaw, and needed something, another diode, > resistor, or > something, but I cant remember what they said, or who said it. > > I use the 1 amp 14,000 volt diode bricks in the circuit, and maybe > something to do with switching speeds, bias, or something, but when I > invoke > the circuit, I get big spurs out the sides, out to 30kc each side 40 > db down. > The mod monitor says the modulation is getting limited to 90% > or whatever I set it to, but running it is even worse than over > modulating. > I use this circuit in a number of rigs with the same results. > > The audio is clean, and I even added some resistors to the > plates of the > 811a > mod tubes, grids are swamped, adjusting the various voltages and > drives on the 4d32 rig has zero effect on the spurs. > > Sure would like to get the circuit to work well, as I can run > the audio > up much more and load the negative spikes. > I don't want to run into it heavy, just trim some peaks off > the negative > side. > > Thanks for any info, > Brett > N2DTS > > > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio > > > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio
[AMRadio] Hamvention
Anyone looking for a ride to Dayton from Johnstown and sharing my flea market spots? Inquire. Thank you. Dave, W3ST Secretary to the Collins Radio Association Publisher of the Collins Journal www.collinsra.com --- StripMime Report -- processed MIME parts --- multipart/alternative text/plain (text body -- kept) text/html The reason this message is shown is because the post was in HTML or had an attachment. Attachments are not allowed. To learn how to post in Plain-Text go to: http://www.expita.com/nomime.html ---
RE: [AMRadio] RE: negative cycle loading
Hi Bret: Many of us have played with neg cycle loading to find the same thing that you have found. You would need a low pass filter after the limiting circuit but these things make the audio have resonate peaks and limited freq response. (poor sounding) If you have good freq response in the lows then your audio will probably be lopsided anyway, especially if you talk close to the mic. SEE - http://www.qsl.net/wa5bxo/asyam/aam3.html Good luck, John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Brett Gazdzinski Sent: Sunday, April 04, 2004 10:51 PM To: amradio@mailman.qth.net Subject: [AMRadio] RE: negative cycle loading Hello all AM,ers. I was running the new 4d32 rf deck on the air over the weekend, and it works very well. I 'stole' the 811a modulator from the 812a rig to modulate the 4d32 rig till I get the kt90 mod deck built. After many and various tests of different voltage and currents on the plates and screens, etc, it seems to like running at 1100 volts and 300ma, for about 220 watts out, although I can get 300 watts out. It modulates well, up to 900 watts pep. But my negative cycle loading setup seems to introduce spurs out the sides when it comes into play. I looked at it on the spectrum analyzer. I use the 3 diode, resistor, and separate power supply that sets the negative percentage (using a variac). I once talked with someone on the air about this circuit, and they told me it had a design flaw, and needed something, another diode, resistor, or something, but I cant remember what they said, or who said it. I use the 1 amp 14,000 volt diode bricks in the circuit, and maybe something to do with switching speeds, bias, or something, but when I invoke the circuit, I get big spurs out the sides, out to 30kc each side 40 db down. The mod monitor says the modulation is getting limited to 90% or whatever I set it to, but running it is even worse than over modulating. I use this circuit in a number of rigs with the same results. The audio is clean, and I even added some resistors to the plates of the 811a mod tubes, grids are swamped, adjusting the various voltages and drives on the 4d32 rig has zero effect on the spurs. Sure would like to get the circuit to work well, as I can run the audio up much more and load the negative spikes. I don't want to run into it heavy, just trim some peaks off the negative side. Thanks for any info, Brett N2DTS ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
