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Tank eff......WAS 3 - phase HV supply
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pentalab
--- In ham_amplifiers@..., "PA3DUV" <pa3duv@...> wrote:
minus loss in the pi-network. Some of the output in a GG amp is coming from the driver, soefficiency is NOT= output*100%/input power... ### How come all the tetrode fellows always say that ?? We carefully measured the eff on this latest 6000A7 linear... and got 67%. Now granted... the wattmeter slug could be a little high... the plate current + HV meter's could be a little low... skewing the results. ### Figure maybe 1% loss in the tank circuit... from the coil. And more like almost 2% on 10m.[ 1-2% of the power output] The kicker is.... on 10m...all that tank coil heat is being dumped into just 2 x turns..... vs less heat being dumped into the ENTIRE coil (or a portion of it)... on the lower bands. ### In various tests I have done... one would think that on say a 20-10m coil.... that when on say 15m.... that the adjacent unused portion of the coil would heatsink the used portion...... it sorta does... poorly. It ends up the used portion will get hot... the unused portion [next turn over] runs barely warm... go figure. ### BTW.... most Vac caps have an unloaded Q of around 5000.... compared to a typ tank coil of 100-300. IMO... most of the tank losses are going to be in the tank coil... interconnecting straps.... bandswitch contacts, etc. ### You need very very few watts to heat up a tank coil....esp hollow tubing. With solid material... like say 8 ga wire [used on the L4B 2 x 3-500Z] used on 80/40m.. or say solid 6 ga wire used on some 20m coils.... it just takes longer to heat up..... the flipside is... with any solid material.... it takes a helluva lot longer to cool down.... cuz of the the stored up heat inside a bigger thermal mass. ### On a related subject.... if I remember correctly, in Eimac's .. "care and feeding" for thermal properties... copper was ... '1.0' and aluminium was '.57' IE: aluminium doesn't conduct heat worth banana's... compared to copper ! Steel, and stainless steel is a LOT worse......... just something to keep in mind. ## A few months back.... I bought a Fluke "Mini 62" IR point and shoot thermonter.... comes with a built in laser pointer.... and can be switched from C to F as well. Works slick.... and will give instant readings onto one LCD display ... and a 2nd display will always hold the peak highest temp. [both backlit to boot] By holding the trigger down solid... and moving the laser pointer about slowly... or quickly.... you can find hot spots all over the place ! You can see quickly where you are leaking heat from the outside of a home.... measure exhaust manifold temps, xfmr's... tank coils... find where ur attic is not insulated properly [heat radiating down from a ceiling... in just one spot], and doz's of other uses..... like measuring exhaust air temp from a linear... Air conditioning problems in the home or car. This Fluke 62 goes from below freezing [instant temp readings of ur fridge/deep freezer] to something like 900 deg F. It will easily differentiate between one part of a tank coil.... and another portion... just a few mm away. A great bargain for around $100.00 Shop around. ### IMO.... since a huge portion of the drive power on a GG linear [ in this case, 640w of the 800 w of drive used] appears in the output.... I'd consider that ... "free extra eff". ### In any event... anode dissipation is REDUCED... if apparent eff is UP. ## DC plate input - power out = anode diss. What am I supposed to do.... subtract the drive power... from the power output 1st.... THEN calculate plate diss ??? Nobody is about to do that.... so why bother subtracting the drive power from the output, to cal eff ? ### I tried several experiments by varying the loaded tank Q on various bands... and also varying the loaded tank Q on the tuned input network. Now Rauch will tell you tank Q makes no diff.. and is not important.... and a loaded Q of "22" is just fine..... fact is loaded Q on a tank circuit DOES make a big difference. A loaded Q of around 3.3 for a tuned input is fine [this would equate to Q =2 doing it Rich's way]. A loaded Q of 10-12 [new method] [ 8-10 old method] is ample for the high power PI output. You start running a Q of 12-22 [new method].... you can easily see, and measure effects asap. The circulating currents skyrocket... tank coils + bandswitch / roller inductor conacts heat up.... eff DROPS, amp tuning becomes narrow banded... requiring more frequent tune ups, when u qsy etc. ### On a tuned input.... I tried a Q of 5.... eff drops..esp on the higher bands. We used bird line sections on both the input/output of the tuned input circuit [consisted of 2 x broadcast variables + a tapped 4 uh coilt] output through the 2nd line section... then into a 50 ohm load was 150-160w . By INcreasing the small coil's uh tap... just a tiny bit..... lowering the Q.... and power out of the tuned input... shot up to 195 w. ### with too high a Q on a tuned input... we could actually get the 5/32 " solid copper 4uh coil good and warm on the high bands 20-17-15m. ### IF the tuned input is NOT done correctly..... it will kill ur eff.. real fast. Locating the C2 tuned input variable cap closer to the tube socket/ and/or installing a small 100 pf NPO doorknob next to the socket..[ in effect moving a portion of C2 closer to the socket] will improve the eff on the higher bands. ### I'd say we may well be arguing semantics here.... but I'd say it's just one more advantage of GG amps.... better apparent eff... and slightly lower plate diss. Later... Jim VE7RF 73 |
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PA3DUV
开云体育> ## A few months back.... I? bought a
Fluke? "Mini 62"?? IR point and
> shoot thermonter.... comes with a built in laser pointer.... and can > be? switched? from C? to F as well.??? Works slick.... and will? > give? instant readings onto? one LCD? display ?
2 weeks ago I checked out? my twin GU84B
tetrode amp with that.
?
Running 6 kW on 7 MHz into the R&S dummyload I
found the following hot spots:
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The connection between tubular wound 20 meter coil
and the lead to the toroidal 40/80/160 meter coil
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The coil section on the INSIDE of the
toroid
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The connection from the coil to the
bandswitch
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The hottest point was the coil section INSIDE the
toroid, 200C + was measured
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The DC blocking caps (2 in parallel) remained
remarkable cool, no significabt temperature rise.
?
The anode coolers went up to 95C
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The 10-20-30 meter tank coil section went up to
130C
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I'll post some pictures of the actual measurement
when I'm back home.
?
Cheers from YMM, Alberta,
Dick, PA3DUV
?
?
?
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Peter Voelpel
________________________________
From: ham_amplifiers@... [mailto:ham_amplifiers@...] On Behalf Of pentalab Some of the output in a GG amp is coming from the driver, soefficiency is NOT= output*100%/input power... ### How come all the tetrode fellows always say that ?? We carefully measured the eff on this latest 6000A7 linear... and got 67%. Now granted... the wattmeter slug could be a little high... the plate current + HV meter's could be a little low... skewing the results. lets assume you drive the 3CX6000 with 1KW.your wattmeter ### Figure maybe 1% loss in the tank circuit... from the coil. And more like almost 2% on 10m.[ 1-2% of the power output] The kicker is.... on 10m...all that tank coil heat is being dumped into just 2 x turns..... vs less heat being dumped into the ENTIRE coil (or a portion of it)... on the lower bands. ### In various tests I have done... one would think that on say a 20-10m coil.... that when on say 15m.... that the adjacent unused portion of the coil would heatsink the used portion...... it sorta does... poorly. It ends up the used portion will get hot... the unused portion [next turn over] runs barely warm... go figure. shure, it must be### You need very very few watts to heat up a tank coil....esp hollow tubing. With solid material... like say 8 ga wire [used on the L4B 2 x 3-500Z] used on 80/40m.. or say solid 6 ga wire used on some 20m coils.... it just takes longer to heat up..... the flipside is... with any solid material.... it takes a helluva lot longer to cool down.... cuz of the the stored up heat inside a bigger thermal mass. one reason I use bigger material for the coils and strips### IMO.... since a huge portion of the drive power on a GG linear [ in this case, 640w of the 800 w of drive used] appears in the output.... I'd consider that ... "free extra eff". Not really, you have to pay the bill for it...### In any event... anode dissipation is REDUCED... if apparent eff is UP. No, that part of the efficiency is dissipated in the driver## DC plate input - power out = anode diss. What am I supposed to do.... subtract the drive power... from the power output 1st.... THEN calculate plate diss ??? Nobody is about to do that.... so why bother subtracting the drive power from the output, to cal eff ? not to cheat yourself ### with too high a Q on a tuned input... we could actually get the 5/32 " solid copper 4uh coil good and warm on the high bands 20-17-15m. Very true, in high impedance output networks you are obliged to run high Qas the minum plate C is too high for >lower Q I guess the 5/32" coil is at the cathode?### IF the tuned input is NOT done correctly..... it will kill ur eff.. real fast. Locating the C2 tuned input variable cap closer to the tube socket/ and/or installing a small 100 pf NPO doorknob next to the socket..[ in effect moving a portion of C2 closer to the socket] will improve the eff on the higher bands. yes, you must avoid long leads there### I'd say we may well be arguing semantics here.... but I'd say it's just one more advantage of GG amps.... better apparent eff... and slightly lower plate diss. No, not in the same class of operation, like AB1 in GC and AB2 in GG.when you compare efficiency, it will be >the same. Efficiency is much higher in class B73 Peter |
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Peter Voelpel
Hi Dick,
200° on a iron powder toroid is pretty high. That will raise your circuit L at least by 4%. I replaced many low band toroidsin Command amps... I wonder what the temperature of your 10m coil is at that 6KW 73 Peter ________________________________ From: ham_amplifiers@... [mailto:ham_amplifiers@...] On Behalf Of PA3DUV The hottest point was the coil section INSIDE the toroid, 200C + was measured The 10-20-30 meter tank coil section went up to 130C |
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GGLL
PA3DUV escribi:
> ## A few months back.... I bought a Fluke "Mini 62" IR point andHow are these connections made?. Mechanically wrapped and then soldered?, with maybe siver solder?. Best regards Guillermo - LU8EYW. P.S.: curious to know how one do at those power levels. The coil section on the INSIDE of the toroid |
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FRANCIS CARCIA
Danger that toroid must be getting to the curie temperature not a good thing when it changes forever..gfz
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Show quoted text
GGLL wrote:
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pentalab
--- In ham_amplifiers@..., "Peter Voelpel" <df3kv@...>
wrote: current. 1" tubing for 100A or 1,5" flat copper stripsone reason I use bigger material for the coils and strips #### partially agreed. There is no way .5" tubing is going toif I am space limited I blow air through smaller tubing handle 50 A.... maybe 36 A. Depends whether RTTY/SSB... and also what Freq. Skin depth at 1.8 mhz = .05mm Skin depth at 30 mhz = .01 mm ....... a 5:1 ratio ! ### 3 A of plate curent x Q of 10 is gonna result in aprx 30- 36 A of circulating current in the pi-net. ### 1.5+ " wide flat strap is easy to wind for 10m... than 1" tubing coil. 3/4" tubing is about the upper limit for practical tubing winding....esp with an aprx 3" ID for 10m. ### with too high a Q on a tuned input... we could actually getrun high Q as the minum plate C is too high for >lower QI guess the 5/32" coil is at the cathode? #### Either insert .6 uh b4 the main PI-NET [or pi-L] or just tap into the .6uh point... with the vac tune cap. Then.. u can transform the plate load Z DOWN to something lower... the PI/PI-L can handle. Yes, the 5/32" solid CU coil IS the 4.0 uh tuned input coil. GG. cathodeUnless you are running class B in the GG amp and AB1 in grounded when you compare efficiency, it will be >the same.### Class B in any GG amp is NOT linear. Class B implies aEfficiency is much higher in class B 180 deg conduction angle.... IE bias set so idle current is exactly zero ma..... which would result in lousy TX imd. ### A SB-220.. with a 5.0 v zener for bias, has a 210 deg conduction angle idles at, I think 180 ma. ## Myself and others... bitched to Eimac about the Class B nonsense in all of Eimac's older literature... it finally got corrected..... GG linears.... drawing as little as 1 ma... are actually AB-2. ### I concur with everything else though. I posdted a few more pix as well. later... Jim VE7RF 73 |
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Peter Voelpel
________________________________
From: ham_amplifiers@... [mailto:ham_amplifiers@...] On Behalf Of pentalab run high QVery true, in high impedance output networks you are obliged to as the minum plate C is too high for >lower Q#### Either insert .6 uh b4 the main PI-NET [or pi-L] orI guess the 5/32" coil is at the cathode? just tap into the .6uh point... with the vac tune cap. Then.. u can transform the plate load Z DOWN to something lower... it does not help much if you need to transform down from 3kohms## Myself and others... bitched to Eimac about the Class B nonsense in all of Eimac's older literature... it finally got corrected..... GG linears.... drawing as little as 1 ma... are actually AB-2. AB2 only works with modern high mu tubes, to get gain from older tubes youneeded class B ### I concur with everything else though. I posdted a few more pix as well. very nice!73 Peter |
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PA3DUV
开云体育Peter,
?
The 200 C was the coil wire, not the toroid
itself.
The toroid?barely heated up.
?
Cheers, Dick
PA3DUV
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pentalab
--- In ham_amplifiers@..., PA3DUV <pa3duv@...> wrote:
#### 200 deg C = 400 deg F !! Which imo is way too hot. ### Looks like the taps are done with teflon coated wire ?? Teflon, although rated at 250 deg C.... is usually maxed out.. and never run above 200 deg C. The teflon coated wires used for tank coil taps will simply hold the heat in.... it won't be able to escape. .... except for the hot connections at each end of the wire... where it terminates. ### On my 3CX-3000A7 HB lineear... I used wire for temp taps on the 3/8" tubing coil.... just for doing the MFJ test set up.. with the usual resistor between anode and chassis. Worked fine.... but when I replaced the temp small ga wire with 3/4" wide strap.... the mfj was off.... turns out the temp wire taps had MORE inductance than the 3/4" wide strap. I had to increase the tune C to compensate. Later on, I moved the tap again.... so I would end up with the desired uh..... with strap being used. ### Now I never use wire for temp coil taps. ### I don't see any air being blown about the tank compartment.. for cooling tank coils, bandswitch, [looks sorta like a model 86] etc. ### On Emtron's website... as of 2 mins ago... the DX-4 is NOT listed anywhere !! Nor is it listed under "orders" or anywhere else. However... do a google on dx-4... and loads of stuff appears. I know it's an export only. Is it still being made ???? ## In any event.... the Fluke Mini 62 pistol grip IR thermometer is an invaluable tool ! I USED to do it the old way..... run a dead cxr.... get stuff hot.... with one finger hovering 1" away from a tank coil..... shut off the cxr... then start "touching" stuff..... and burning my finger. With HV every where... I highly DON'T reccomend this method.... hence the Fluke 62 .... faster, SAFER.. precise readings in either C or F. ### Works on LC networks with NPO caps, coils etc. One would think every commercial amp manufacturer would have a few on hand. Later... Jim VE7RF supply [mailto:ham_amplifiers@...] On Behalf Of PA3DUVwas measured |
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pentalab
--- In ham_amplifiers@..., "Peter Voelpel" <df3kv@...>
wrote: ### Nonsense.... sure it does. You can easily drop a 3 K ohm plate load Z ...down to 354 ohms on 29.7 mhz. .... just by adding .5 uh b4 the pi net. Then C1 = 23.9 pf L = .34 uh C2 = 280 pf ## Make it .6 uh.... and C1= 80pf plate load Z = 173 ohms. ### Use GM3SEK's excellent PI PI-L spreadsheet [free on his site] and toss some numbers in.... then try juggling the value of the suppresssor inductance AND /OR this extra uh anywhere between tube anode and main pi net. Any extra uh b4 the pi net makes a HUGE difference to the transformed plate load Z.. on the upper bands.... with a decreasing effect as u go lower in freq. ### Then try it on the mfj test jig.... it actually works dead on. Just make sure you measure the uh 1st. I use a B+K 875- B.... available from Mouser, etc..... measures down to .1 uh.... and down to .1pf My #1 tool in the shop ## as a side bonus... since the transformed plate load Z drops.... harmonic suppression goes up ! ### still, If u want 10/12 m..... you ALSO need either a low C vac cap.... OR a low C air variable. Alpha, etc... uses a 2 x section air variable cap.... and bandswitches em.... the 2nd section of course is a tiny thing... with 2 x stator + 3 x rotor plates = real low min C. ### Now I don't get wound up about harmonic suppression too much. Any mono band ant is going to be sky high swr on it's 2nd harmonic. The ant may well resosnate on it's 3rd harmonic.... BUT a simple PI will have -50 db of 2nd harmonic suppression. .... depending on loaded tank Q.... and also what the ratio of the transformed tube Z is. Lower transformation's always give higher harmonic suppression. ## glad u enjoyed the pix. I'm trying to dig one up that shows the bias board assy. Later.... Jim VE7RF |
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Dick
See the pics in the photo section.
The taps are done with bare wire, but the coil is done with double wire in a teflon sleeve. In SSB service this works good, but in my opinion the toroid wound coil section gets a bit too hot in higher duty modes. ### On Emtron's website... as of 2 mins ago... the DX-4 is NOTThe DX4 is currently made in larger numbers than all other Emtron HF amps according to Rudi Breznik. Because of the relatively low B+ voltage the tank caps are air caps for both tune and load which reduces the costs for the tank circuit. More info including pics of the 3 phase power supply on the Emtron owners yahoo group, There are rumours about the design of a GU84B three holer but I have no confirmation for this. Cheers, Dick PA3DUV --- In ham_amplifiers@..., "pentalab" <jim.thomson@...> wrote: and never run above 200 deg C. The teflon coated wires used forthe wire... where it terminates.taps on the 3/8" tubing coil.... just for doing the MFJ test setwith 3/4" wide strap.... the mfj was off.... turns out the tempwire taps had MORE inductance than the 3/4" wide strap. I had totap again.... so I would end up with the desired uh..... with strapWith HV every where... I highly DON'T reccomend this method....HV supply+[mailto:ham_amplifiers@...] wasmeasured |
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Peter Voelpel
Hi Dick,
How hot is the step-down toroid on the output getting? The problem with air caps will be the rotor contacts which have to carry about 25A and probably more on 10m in the DX4. It looks they are using quite normal contacts on the caps. Even the very high power caps of Oren Elliot are only good for 30A. I use vacuum variables for this reason and their size also in my low impedance amps like 3xRS1072C 73 Peter ________________________________ From: ham_amplifiers@... [mailto:ham_amplifiers@...] On Behalf Of Dick See the pics in the photo section. The taps are done with bare wire, but the coil is done with double wire in a teflon sleeve. In SSB service this works good, but in my opinion the toroid wound coil section gets a bit too hot in higher duty modes. ### On Emtron's website... as of 2 mins ago... the DX-4 is NOTThe DX4 is currently made in larger numbers than all other Emtron HF amps according to Rudi Breznik. Because of the relatively low B+ voltage the tank caps are air caps for both tune and load which reduces the costs for the tank circuit. |
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PA3DUV
开云体育Hi Peter,
?
That is a bit difficult to measure it with the IR
meter since the coil on the toroid gets rather hot.
The only way I was able to get an indication of the
toroid temperature?was to run a 6 kW carrier after which I switched the
drive off and poked with my finger between the coil turns in an attempt to feel
the toroid surface temperature.
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The toroid was way below 60 C as I could touch it
without hurting my fingers.
?
Cheers, Dick
PA3DUV?
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