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Re: Tube heater current
Robert B. Bonner
It was done because the TR-4/3 went mobile and the filaments ran off the
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battery. -----Original Message-----
From: ham_amplifiers@... [mailto:ham_amplifiers@...] On Behalf Of pentalab Sent: Tuesday, December 19, 2006 6:12 PM To: ham_amplifiers@... Subject: [ham_amplifiers] Re: Tube heater current --- In ham_amplifiers@..., GGLL <nagato@...> wrote: with the output tubes in a Drake TR-4 I was committed to repair. It has three 6JB6in parallel to achieve 200..220 watts out at 80, less at the upper bands. Tomy surprise, the tubes (Penta brand) appear to be 6V but to take a lot moreheater current than the data sheet specified 1.2A. ### The Drake TR-4 and older TR-3 all used 3 x 12JB6's... with all the 12.6 v fils in parallel. The drake T4X/C used a pair of 6JB6's [6.3 v fils] with the two fils in series. This was done so the mating AC-3/4 power supply would run either the TR- 3/4 xcvr.. or the T4X/C TX. Later....... Jim VE7RF
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Re: Heatsink relationship
Robert B. Bonner
That's why I build all my antennas out of steel.
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My 80 meter beam weighs 62,000 pounds. BOB DD -----Original Message-----
From: ham_amplifiers@... [mailto:ham_amplifiers@...] On Behalf Of craxd Sent: Tuesday, December 19, 2006 6:00 PM To: ham_amplifiers@... Subject: [ham_amplifiers] Re: Heatsink relationship Actually, copper weighs a little more than steel. Copper: 0.295 pounds In^3 Aluminum: 0.098 pounds In^3 Steel: 0.283 pounds In^3 Copper also has the lowest yield strength of all three with steel being the highest. Best, Will |
Re: Tube heater current
GGLL
pentalab escribi:
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Perhaps there were variations due to availability of certain tubes??; I have two schematics and in both figures the use of 6JB6's in parallel (3.6A intended heater current), but with a couple minor changes in other tubes; these parallel 6JB6 are in series with a string of many tubes which 6V filament currents added is also 3.6A, and the whole series arrangement fed with 12.6VAC. When the owner put the Penta's with the added heater current, voltage drop was wrong, a lot more than 6.3V at the miniature (7 and 9 pin) tubes, and a lot less than 6.3V at the "6JB6". Now I figure why (also why) Drake recommended to use only Sylvania tubes. Best regards Guillermo - LU8EYW. --- In ham_amplifiers@..., GGLL <nagato@...> wrote: |
Re: Tube rebuilder
On Dec 19, 2006, at 7:57 AM, n6jp wrote:
Less filament V., more filament A., different socket. Uncheap.- due to its abundance of feedback C, i f I had an amp whoseWhat are the typical changes that need to be addressed in switching R. L. Measures, AG6K, 805.386.3734 r@..., rlm@..., www.somis.org |
Re: Tube rebuilder
Thanks. The 3cx1200D7 has less feedback C that the A7 version.
On Dec 19, 2006, at 1:27 PM, ad4hk2004 wrote: Sorry, I need to be more specific... 3CX1200D7 (YU121)R. L. Measures, AG6K, 805.386.3734 r@..., rlm@..., www.somis.org |
Re: Tube rebuilder
On Dec 19, 2006, at 3:25 PM, pentalab wrote:
--- In ham_amplifiers@..., R L Measures <r@...> wrote:Does it use g-g config?talk There is no such thing as a broadbanded input for g-g. Did Henry Radio get out of the amplifier business?inspected,not the R. L. Measures, AG6K, 805.386.3734 r@..., rlm@..., www.somis.org |
Re: Tube heater current
pentalab
--- In ham_amplifiers@..., GGLL <nagato@...> wrote:
with the output tubes in a Drake TR-4 I was committed to repair. It has three 6JB6in parallel to achieve 200..220 watts out at 80, less at the upper bands. Tomy surprise, the tubes (Penta brand) appear to be 6V but to take a lot moreheater current than the data sheet specified 1.2A. ### The Drake TR-4 and older TR-3 all used 3 x 12JB6's... with all the 12.6 v fils in parallel. The drake T4X/C used a pair of 6JB6's [6.3 v fils] with the two fils in series. This was done so the mating AC-3/4 power supply would run either the TR- 3/4 xcvr.. or the T4X/C TX. Later....... Jim VE7RF
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Re: Grounded Screen Configuration
pentalab
--- In ham_amplifiers@..., "craxd" <craxd@...> wrote:
shell type cabinet made of aluminum or like to C's placed together at 90then is placed inside, generally at the rear of the cabinet. I wouldcopper or steel where I can solder the bypass caps directly to it or anycabinet is aluminum anyhow. Aluminum is supposed to be better atshielding, but I'm not convinced that is is that much better than steel.#### steel...esp Stainless steel.. doesn't handle RF worth a damn. Don't believe me.... tey making a hairpin match from stainless steel wire..... right at the dead center point it will turn BLACK every time [ electrical neutral point, zero V... current is max.] If u grnd the mid point to the boom.... u now have a "beta match"... ala hi-hain ants. ### Notive how JA6TAY uses a large copper plate arounf the tube socket on his big metal tube amps..... then it's aluminium. There is one helluva lot of Rf current between the anode and chassis grnded grid on a GG triode amp. ### I used steel chassis's on some hb 6146 B TX's back in the early 70's... a real pain to cut, and drill, and work with. Pland jane sheet metal has a tendency to rust too. I stopped using steel for fronta and rear panels as well. Steel is great for removable sides of rack cabinets... and the actual rack itself... that's it. Later... Jim VE7RF |
Re: Heatsink relationship
craxd
Actually, copper weighs a little more than steel.
Copper: 0.295 pounds In^3 Aluminum: 0.098 pounds In^3 Steel: 0.283 pounds In^3 Copper also has the lowest yield strength of all three with steel being the highest. Best, Will --- In ham_amplifiers@..., "pentalab" <jim.thomson@...> wrote:
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Re: Heatsink relationship
Harold Mandel
¿ªÔÆÌåÓýBill and Jim, ? In my first response it was mentioned about the fractal relationships of the molecular structure of materials and their exhibitions of varying qualities regarding excitation by energy sources. ? Weight and Mass were never mentioned and maybe should be completely disregarded, as only the structural relationship(s) of the component building blocks were being considered. ? Hal > |
Re: Heatsink relationship
pentalab
--- In ham_amplifiers@..., Bill Turner <dezrat@...>
wrote: easier it is betterfor the wiggling to be picked up ### as I mentioned b4... steel weighs aprx the same as copper...conductor of heat than aluminum.------------ REPLY FOLLOWS ------------ and doesn't conduct heat worth a damn .2 to 1 ratio for steel to copper [all the heat trnasfer tables use copper as the reference = 1] AL is only .57 to 1 Lead is heavy as hell... and doesn't conduct heat worth banana's. Jim VE7RF
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Re: Tube rebuilder
pentalab
--- In ham_amplifiers@..., R L Measures <r@...> wrote:
talk Henry hewith Eimac yesterday and after going over the symptoms on my network?has me convinced that the tube has changed its input impedenceRICH SEZ....Not very likely. What is the Q of the input tuned Pi- #### The 3 k ultra doesn't have a PI net tuned input... it uses broad banded xfmrs back to back, and relays. inspected,not the havemetered, jiggled, and sniffed, and nothing amiss is found... We eyeballs,spent considerable time and effort using VOM, LC meter, MK-I diodes,etc. to prove the mechanical and electrical charateristics of all accurate,and on, and on... We found that the Henry manual is not 100% heatedbut the errors are easily spotted and not significant if you voltagecathode on a 3CX1200>chortle out...above it's nominal and recheck the input impedence and power cathodeWe raised the voltage to 6.8 volts and the input swr to the wattspromptly dropped from 3.8 to 1.9 ... The tube now puts out 1100 ### well rich.. I guess eimac is right... since his input swrwith 48 watts in and the grid current is right at the 200 mils dropped like a rock.... still not flat..... but I don't hink any of the 3k/8 k ultra's were ever dead flat.... with that broadbanded input. later... Jim VE7RF |
Re: Tube heater current
craxd
Guillermo,
Those tubes are rebrands so it's untelling who actually made them. If it was GE years ago, look to see if there is a series of little dots etched into the glass where the tube number is at. If the dots are there, it's a GE tube. If not, they could be Sylvania, RCA, etc. The thing is, several tube manufacturers made tubes with the same number. However, between brands, some could have differences in current when voltage is applied. One tube could have a lower heater current than another in these. Another thing to look for is that they took one tube number and named it another because the innards were wired the same. That's kind of unscrupulous to do, but has been done. That's the same as replacing a 6JS6C with a 6KD6. If Penta is having new sweep tubes made in China, and having them re- branded, I'd sure like to know about it and what they can get. However, I sure won't pay $50 a piece for any sweep tube. I know for a fact they don't cost that much from China as I had some 6LF6's quoted to me once. By buying in the 1000 lots, they were going to cost about $8.00 each from a prominent Chinese manufacturer. At the most was at $15 each. Best, Will --- In ham_amplifiers@..., GGLL <nagato@...> wrote: with the output tubes in a Drake TR-4 I was committed to repair. It has three 6JB6in parallel to achieve 200..220 watts out at 80, less at the upper bands. To mysurprise, the tubes (Penta brand) appear to be 6V but to take a lot moreheater current than the data sheet specified 1.2A. |
Tube heater current
GGLL
Hello, I want to ask about something that happened this week with the output tubes in a Drake TR-4 I was committed to repair. It has three 6JB6 in parallel to achieve 200..220 watts out at 80, less at the upper bands. To my surprise, the tubes (Penta brand) appear to be 6V but to take a lot more heater current than the data sheet specified 1.2A.
Have you had any experience with a similar thing?. Best regards Guillermo - LU8EYW. |
Re: Grounded Screen Configuration
craxd
--- In ham_amplifiers@..., "Robert B.
Bonner" <rbonner@...> wrote: ways a bunch even with Aluminum used the construction. Correct, but it takes a much thinner piece of steel to equal the same strength of aluminum so they equal out close to the same. Generally, 20 gage steel is used in electronics chassis, and any aluminum is much thicker. I forget what the aluminum gage is being used in most amp chassis, but it's close to 1/8" thick or more. Stainless and aluminum work well together, steel and aluminum corrode. That's the problem with ground connections in amps using aluminum chassis. The screws, washers, and some solder eyelets are steel. Other eyelets are brass which is plated. The problem comes from corrosion between the fastener-washer-eyelet and the aluminum. When this happens, you either lose the connection or have a high resistance at it. I've seen this happen in several squirelly acting amps. I cleaned each connection and used new screws, etc which cured the problem. A soldered connection though is worry free. Steel used as electronics chassis is generally plated to stop corrosion as in some transceivers. I'm not sure how zinc plated steel would act with aluminum though as I have seen this used. Copper can corrode forming copper oxide on the surface. However, copper was used extensively in test equipment as shielding and the main chassis. In them, all the grounds were soldered. Copper tarnishes badly and with any moisture comes the greengoo... With any condensation you could have a mess. I've never tested this forgalvanic corrosion.copper whatever shielding... Bob, I don't either, but some will argue different. I think steel takes a bad rap for other probelms.
Best, Will |
Re: Tube rebuilder
ad4hk2004
Sorry, I need to be more specific... 3CX1200D7 (YU121)
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denny --- In ham_amplifiers@..., R L Measures <r@...> wrote:
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Re: Grounded Screen Configuration
Robert B. Bonner
Flat and simple, aluminum is lighter. A fully loaded amplifier ways a bunch
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even with Aluminum used the construction. You could get by with making the top socket level plate copper. Stainless and aluminum work well together, steel and aluminum corrode. Copper tarnishes badly and with any moisture comes the green goo... With any condensation you could have a mess. I've never tested this for galvanic corrosion. I don¡¯t believe there is any difference between aluminum and steel, copper whatever shielding... BOB DD -----Original Message-----
From: ham_amplifiers@... [mailto:ham_amplifiers@...] On Behalf Of craxd Sent: Tuesday, December 19, 2006 2:53 PM To: ham_amplifiers@... Subject: [ham_amplifiers] Re: Grounded Screen Configuration The way they're building most amps these days is to use a clam shell type cabinet made of aluminum or like to C's placed together at 90 degree angles. The actual tube chassis is a box made with aluminum just large enough to fit the tube sockets in the top of it. This then is placed inside, generally at the rear of the cabinet. I would rather have the top of this box-tube chassis made with either copper or steel where I can solder the bypass caps directly to it or any other ground connection. I've used steel in a lot of amps, and personally I think it takes a bad rap over other probelms that are not its fault. Of course copper would be the best, however there's not enough steel here to hurt anything, and the rest of the cabinet is aluminum anyhow. Aluminum is supposed to be better at shielding, but I'm not convinced that is is that much better than steel. The only difference would be the resistivity of the material, but the area is so much that this would be really low. I've seen some big amps built on steel chassis that were clean and shielded well without spuriuos radiation problems. The major advantage to aluminum is that it's a lot easier to work with and is why it's prefered in my opinion. For years before aluminum was used, steel chassis were used with very good results. Best, Will --- In ham_amplifiers@..., "Peter Voelpel" <df3kv@...> wrote: places where RF flows and no soldering at all.[mailto:ham_amplifiers@...] On Behalf Of craxdscreen is tied to. There's no way to have a voltage difference if thecase, you would have a difference of 800 Vdc between the cathode andchassis ground and tied to the cathode.drivingscreen voltage isvoltage as the tubetubepassive grid.If the screen is bypassed correctly with capacitors at the tube socket, but rather use steel or copper. The reason being is I canbetween the two materials in how they're fastened together, etc. I've seento an aluminum chassis. This even when they use a wavy tooth lock Yahoo! Groups Links |
The cathode and ground.
craxd
All,
Here's my thoughts on the naming conventions when using the term ground in a tube circuit. Ground, or chassis ground is the ground that goes back to the power source. The chassis is most always tied to this "ground" and is termed chassis ground. In most tube circuits, except ones that have cathode bias, they tie the cathode to chassis ground along with the negative lead from the HV supply. This is therefore ground and is the 0 Vdc reference when measuring all voltages. There actually may be a slight difference in voltage in a directly heated cathode because of the resistance of the heater transformer windings. That is when the C.T of the transformer is tied to chassis ground. If the C.T is biased, then it changes things completely. When the cathode of a tube is biased, and the B- lead from the HV supply is attached to it, and not chassis ground, this brings the cathode to a negative potential when measured from chassis ground. Terman, in his infinite wisdom mentions this in the Radio Engineers Handbook. Here, he mentions that in a grounded grid amp, with the cathode biased, the potential difference between the cathode and the control grid which is tied to chassis ground is "less negative" and not labled positive. This is due to folks misinterpreting the B- as ground when in fact the only way it can be called ground is if the cathode is directly tied to it, and there is no potential difference between the two. Now I know all will say everything is referenced from the cathode, but this is only the case in a cathode biased amp where the cathode is not tied to the actual ground. Most all the voltages of any circuit are read from the ground or chassis ground whichever it may be for the 0 Vdc reference. The only circuit that isn't is a cathode biased tube. Thus, any voltage on either side of 0 Vdc is either a positive or negative voltage. Here, I totally agree with what Terman said, in that he wouldn't call a voltage positive between the control grid and cathode in a cathode biased amp, even though there's a potential difference here. He says it's less negative, not positive since to be positive, it would have to show a positive reading from ground which it can not. However, when placing the negative lead of a voltmeter to the cathode of a cathode biased tube, and one to the grounded grid will show a positive voltage. One here is actually viewing the difference between 0 Vdc (ground) and a negative voltage, not a positive one since the positive lead of the meter attaches to chassis ground with the grid. This even though an electron flow would happen between the cathode and control grid over the difference in voltages. This could happen between any grid that is at chassis ground or 0 Vdc and or above the cathode since there's a potential difference. However, there's a difference here on either side of chassis ground, positive and negative. One also measures the screen voltage and bias for the control grid to chassis ground. This is shown on any schematic. If the cathode is biased, these voltages will be different when measuring between chassis ground, or the grids, to the cathode. In a directly grounded cathode like is used in many circuits, all voltages are taken from chassis ground. So saying all voltages are measured from the cathode kind of goes out the window. In my opinion, a cathode biased tubes voltages (between the cathode and chassis ground) should always be called less negative instead of positive the same as Terman mentioned. This because the voltages can never go over the 0 Vdc reference of chassis ground. One should never use the term ground unless one is actually measuring a voltage to it. Then, one has to use either negative or positive to describe the voltage. Maybe one could use B- in place of ground in any description for a cathode biased tube? This then will stop any confusion that may exsist between a circuit where the cathode is actually grounded, and one that's biased negative compared to chassis ground. This would support all the definitions of voltage in either positive or negative. If using "ground" to describe any circuit, it can be confusing when a cathode biased tube circuit comes up when describing voltages. Others may not agree, but I'm surely sticking with Terman as he's the only one that has really made sense in describing what is actually going on and sticking with the definitions. Best, Will |
Re: Grounded Screen Configuration
craxd
The way they're building most amps these days is to use a clam shell
type cabinet made of aluminum or like to C's placed together at 90 degree angles. The actual tube chassis is a box made with aluminum just large enough to fit the tube sockets in the top of it. This then is placed inside, generally at the rear of the cabinet. I would rather have the top of this box-tube chassis made with either copper or steel where I can solder the bypass caps directly to it or any other ground connection. I've used steel in a lot of amps, and personally I think it takes a bad rap over other probelms that are not its fault. Of course copper would be the best, however there's not enough steel here to hurt anything, and the rest of the cabinet is aluminum anyhow. Aluminum is supposed to be better at shielding, but I'm not convinced that is is that much better than steel. The only difference would be the resistivity of the material, but the area is so much that this would be really low. I've seen some big amps built on steel chassis that were clean and shielded well without spuriuos radiation problems. The major advantage to aluminum is that it's a lot easier to work with and is why it's prefered in my opinion. For years before aluminum was used, steel chassis were used with very good results. Best, Will --- In ham_amplifiers@..., "Peter Voelpel" <df3kv@...> wrote: places where RF flows and no soldering at all.[mailto:ham_amplifiers@...] On Behalf Of craxdscreen is tied to. There's no way to have a voltage difference if thecase, you would have a difference of 800 Vdc between the cathode andchassis ground and tied to the cathode.drivingscreen voltage isvoltage as the tubetubepassive grid.If the screen is bypassed correctly with capacitors at the tube socket, but rather use steel or copper. The reason being is I canbetween the two materials in how they're fastened together, etc. I've seento an aluminum chassis. This even when they use a wavy tooth lock |
Re: Heatsink relationship
Harold Mandel
¿ªÔÆÌåÓýDear Bill, ? You left yourself wide open for this one: ? ¡°Why not?¡¯ ? Sorry, Bill. I hadda get that one out. Ooooooooo. ? However, on a less serious note, let¡¯s consider the arrangement of the stuff. ? Remember how it was mentioned that microscopic examination of aluminum resembled the foam at the top of a recently-filled tank of diesel fuel, all bubbly? ? The arrangement of ¡°stuff, ¡° and let¡¯s just progress to molecules, as we¡¯re both adults, has an arrangement that can be mathematically described with Fractal Geometry inasmuch as certain arrangements lend well to heat conductivity, some to electrical conductivity, some to attenuation of ionizing radiation, (e.g., Alpha, Beta, Gamma, X-Ray, &c.), and other arrangements respond poorly. In Benoit Mandelbrots formulation of how the microcosm resembles the macrocosm other students discovered that the seemingly random arrangement of molecules really wasn¡¯t, and those relationships affected the ¡°energy-handling spectra.¡± ? So to answer your questions below, with the most honest answer I can devise, is that the molecular arrangement of the materials you ask about, lend themselves poorly or greatly to the transfer of thermal energy. ? In studying FG some years ago, I experimented with a waterbed in my New England home where we kept the room temperature at a purely Draconian level, but the waterbed needed to be heated so we didn¡¯t develop pneumonia. The experiment lined the? wooden inner shell with ¡°space blankets,¡± a layer of Blue Board, and another layer of space blanket on the five surfaces under and in around the waterbag. The daytime top covering was a removable sandwich of space blankets and blue board filling. ? The idea was to not only attenuate but to diffuse the infra red energy being transmitted by the excited water molecules. (The heater element was on top of the bottom sandwich.) ? The space blankets would reflect energy into the sandwich, and the blueboard would diffuse the radiation. ? On a 24 month, daily charting of the KWH consumed, before and after the experiment it was observed that the waterbed consumed $17.00 worth of electricity per month from November through March, and after the modification the consumption dropped to roughly $1.00 per month. ? ? I do not know anything about materials and why they exhibit certain properties. ? Aside from the fractal relationship affecting thermal conductivity, your guess is as good as mine. ? ¡¯73, ? Hal
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