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Re: Can Grid Dissipation in metal GG triodes be increased ????
craxd
Jim,
What you describe may help a little. The problem is the internal connection from the ring to the grid itself, and it's size. If it's only a piece of wire, you may not gain anything as the wire would be the bottleneck I would think. The ring would help a little by being a larger heatsink for the connection itself, but the grid itself is still wire which it's size and coating (gold, etc) can only take so much current. The ring would have to dissapate the heat from the grid via the internal connection(s). Best, Will From: ham_amplifiers@... [mailto:ham_amplifiers@yahoogroups.com] On Behalf Of pentalab |
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Re: Amplifier Content
craxd
Bill,
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I don't have one now, and haven't since the early 80's when I used it for a whole 9 monts if that (Novice). However, I think everyone that was on the Amps mailer knows what happened in my case so it's kind of a moot point. I'll get one again if the rule changes that supposed to happen eventually do, and to my liking. I made a promise back then in the 80's due to a good friend, and I've kept it up to this date. Best, Will --- In ham_amplifiers@..., Bill Turner <dezrat@...> wrote:
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"New" method of fabricating a better chimney
pentalab
Since Eimac never made a chimney for either a 3CX-3000A7 or a
3CX-6000A7 [or the socket] several after market chimneys have appeared. I purchased the one for the 6000A7. It was solid 1/4" thick teflon... straight up and down, no flanges.... and it's weight held it to the chassis. 6.130" ID 6.630" OD We found that this restricted the airflow up from the chassis too much. [both the ceramic 'stem' on the 3000/6000 are identical.. and much smaller diam than a YC-156 or a 10,000A7. ] For an experiment, I remember W7IUV had fabricated a fiberglass box around his YC-156.. for a chimney. We tried the same trick... except the vertical sidewalls were made from wood... about 9" square... top was also made from wood.... and the original chimney was placed in a groove.. on top of this wooden affair. Now we could increase the hole sizes on the chassis. The result was a huge improvement! Intead of the original 205 cfm... we are now getting an easy 320 cfm [using a Dayton 5C508 dual speed, capacitor start blower]. On the next chimney... we will toss the after market straight up and down chimney... and just increase the vertical sides of the box... and use a solid teflon top lid.. with a 6.130" hole in it. This technique can be used on any metal tube. The after market chimney's for the 3000A7 [4.130" ID] restrict the air too much as well. On one 3000A7 project... I used a SK- 306.. designed for a 4CX-5000A7.. which is a bit too big a diam at the top.... so we filled the gap.. by wrapping a few layers of silicone rubber around the tube.. held in place by a SS hose clamp... worked good. ... since the SK-306 chimney has a flared out base. Eimac specs the 6000A7 for 205 cfm of air. [based on a 50 deg C /121 deg F inlet air temp.] With 320+ cfm... and an inlet air temp of 25 deg C..... we calculated the anode diss is now an easy 8500+ Watts ! Talk about the sleeper of the year. This tube is real easy to increase it's stock anode dissipation. The secret is the small diam ceramic 'stem',makes for larger fins underneath... compared to a say 5000A7/YC-156..... which has a huge diam 'stem'... and a smaller anode cooler. The Dayton 5C508 blower is a dual speed 1100 rpm /1450 rpm unit. Comes with a single oil filled start cap. The over temp protected motor is partially embedded in one end. It draws intake air from both ends. With no back pressure... in free air, it's 765 cfm on high speed..... and down to 320 cfm @ .9" water pressure. They installed clip weights to some of the impellor blades.... so it's perfectly balanced from the factory... like balancing a car wheel. Later..... Jim VE7RF |
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Re: Drake L7
craxd
Tom,
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If the board isn't damaged (traces burnt off), I'd just repair it. I'd think that would be the cheaper way to go. First thing I'd do is to make sure the lightning didn't short out the power transformer(s). If it did, your going to be into some cost. At that, it may be better to just sell it off and try to get your money back, unless you want to repair it. It's a matter of what the cost is as compared to the worth of the amp, plus if you want to do that amount of work. The L7 if I recall does sell pretty high on ebay starting at around ($800 plus). Best, Will --- In ham_amplifiers@..., "tm303" <tmartin@...> wrote:
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Re: Fw: [Amps] Step Start on a 3KA Amp
item.I've heard that Emtron is selling their softstarter as a seperate by doingThis softstarter is a small switcher which chops the AC voltage, Seems to me like the inrush shock to the PS lasts well more thanso limiting the inrush current. 1/180th of a second (2 crossings every full 60 Hz cycle). If their step-start uses SS zero-crossing devices, that means full current is applied 90 degrees (+/- PF) after the moment the ON button is pressed. That's an awfully large amount of current in a very short period of time. Unless there's some documented evidence that proves current is reasonably limited with the use of these SS crossing devices, I think I'll stick to relays and power resistors. Paul, W9AC |
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Re: "New" method of fabricating a better chimney
Peter Voelpel
Hi Jim,
I use heatresistant glass cylinders I get made locally and also use round teflon covers as you, thats works very well. All my blowers are made by EBM. I do not like to boost a tubes rating, I rather prefer then to use a bigger one. I prefer that my GG amps cannot run in too high dissipation at full drive. They should have no problem when the antenna gets lost... 73 Peter --- In ham_amplifiers@..., "pentalab" <jim.thomson@...> wrote: For an experiment, I remember W7IUV had fabricated a >fiberglass |
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Hipot and other equipment for sale
craxd
All,
I have the following four pieces of test equipment for sale; (1) Model 1020-B Megohm Meter by Freed Transformer 1 meg to 100k meg (2) Model 404M3 "Hypot" by Associated Research 4 kV @ 100w (3) Model 3050 sine/square wave generator by B&K Instruments (4) Model 3500 5-1/2 digit DMM by Data Precision I bought these with some other equipment and was going to overhaul each. I've not had the chance to thoroughly test each, and already have other equipment like this, so I'm going to sell these cheap as a lot. The cost for the lot is $75 US Plus shipping. Postal money order prefered. Please e-mail me at: craxd1 at verizon.net Thanks, Will |
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Re: "New" method of fabricating a better chimney
craxd
Peter & Jim,
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I started using a thick fish paper and paper tubing like that used for RF coils. You can buy it in larger diameters. I tried some with some 4CX250B's just to see how it worked and it was ok. The tubing is made from an electrical insulation type paper. The fish paper sheets is the blue or gray type, and about 1/6" thick. It's the same stuff you can make transformer bobins with. The tubes don't get hot enough to do anything to the paper, including the larger tubes if the air is flowing. The paper tubing is made by Precision Paper Tube. They supply the electrical/electronics industry. Oceanstate Electronics has the fish paper. A Google search will quickly find both. Best, Will --- In ham_amplifiers@..., "Peter Voelpel" <df3kv@...> wrote:
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Re: Can Grid Dissipation in metal GG triodes be increased ????
pentalab
--- In ham_amplifiers@..., "craxd" <craxd1@...> wrote:
connection from the ring to the grid itself, and it's size. If it's only apiece of wire, you may not gain anything as the wire would be thebottleneck I would think. The ring would help a little by being a larger heatsink forthe connection itself, but the grid itself is still wire which it'ssize and coating (gold, etc) can only take so much current. The ring wouldhave to dissapate the heat from the grid via the internal connection(s).### The grid in both a 3000/6000/YC-243 is 225 W CCS... and resembles a bird cage. The joke is.. you can use it for a dummy load for your 1000-D . ### The next trick is how to calculate the grid diss ? ### Eimac only has 'specs' on the 6000A7 for GG FM broadcast service. They rant on about 'class C'... but the specs clearly show zero bias operation. The 6000/YC-243 have a MU of 200.... and per Reid Brandon at Eimac.... make an excellent tube for ssb / good imd. ### Eimac can't even tell me what the input Z is in GG.... so we used W7IUV's slick method. Guestimate.. and build for one band..say 40m. After its tweaked for flat swr[while driving the amp] .... leave it alone... and stick the mfj on the input side... and substitute resistors on the cathode side... till the swr is flat on the mfj. What ever this resistance is ... is the tubes's input Z ! Works every time. ### What we see is with 800 w of drive... output is 11,500 watts..... and about 640 ma of grid current. 2.5 A of plate current @ 6800 vdc under load..... all with a dead cxr. ### Eff is 67% on all bands 160-15m. We tweaked the Pi net for a Q of 8-10 #### the tuned input is unique too. Instead of the usual 9x bandswitched 'pi nets'.... we used 2 x broadcast variables ..all 4 x sections strapped in parallel= 72-2080 pf.... and a small 4uh bandswitched coil... made from either 7 or 8 ga solid copper wire. 17 turns 1.5" ID. [BTW... Multronics still makes a 4.4 uh roller coil... made from 8 ga wire] ### We used an extra wafer, so we could pad the pair of broadcast caps on 160m. [4 x 500pf doorknobs per cap] ### We actually installed bird line sections on BOTH sides of the tuned input.... and with 200 w in... were only getting 160w out on 20-17-15m... and 195 on 160-40m. Turns out the Q was TOO high on 20-15m. This nonsense about using a loaded Q of 5 for a tuned input is just that. I'm talking about a real loaded Q of 5.... not Eimac's / Rich's method.. based on C1 only. Rich's Q of 2 is in fact 3.3 to 3.6.... which is about what one wants. ### with a real Q of 5-6... you could actually get 8 ga wire warm ! 200w = 2 A into 50 ohms. ### We increased the UH on 20-17-15m just barely enough... so that power out of the tuned input shot up to 190-195 watts. ### Now with 750-800 watts dead cxr..... the tuned input runs just fine on all bands.... bullet proof. And with vernier's on both caps.... it's just 'dial up by the numbers' . You get real flywheel action to boot. In addition... max grid current and min input swr coincide. ### In actual operation... we pulse tune everything. later... Jim VE7RF |
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Re: Can Grid Dissipation in metal GG triodes be increased ????
Tony King - W4ZT
That is a good point for tubes like the YC-156/179. On tubes like the planar constructed GS-35B, the grid is tied directly to the ring and can move more heat. Unfortunately, the actual construction of the grid itself may actually be the limiting factor on the GS-35.
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73, Tony W4ZT craxd wrote: Jim, |
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Re: "New" method of fabricating a better chimney
Tony King - W4ZT
The straight up and down chimney will work pretty well if the flange is sub mounted below the chassis so air has a better path up through the anode. That's the plan here for the YC-156/179.
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73, Tony W4ZT pentalab wrote: Since Eimac never made a chimney for either a 3CX-3000A7 or a 3CX-6000A7 [or the socket] several after market chimneys have appeared. I purchased the one for the 6000A7. It was solid 1/4" thick teflon... straight up and down, no flanges.... and it's weight held it to the chassis. 6.130" ID 6.630" OD We found that this restricted the airflow up from the chassis too much. [both the ceramic 'stem' on the 3000/6000 are identical.. and much smaller diam than a YC-156 or a 10,000A7. ] For an experiment, I remember W7IUV had fabricated a fiberglass box around his YC-156.. for a chimney. We tried the same trick... except the vertical sidewalls were made from wood... about 9" square... top was also made from wood.... and the original chimney was placed in a groove.. on top of this wooden affair. Now we could increase the hole sizes on the chassis. The result was a huge improvement! Intead of the original 205 cfm... we are now getting an easy 320 cfm [using a Dayton 5C508 dual speed, capacitor start blower]. |
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Re: Censorship/Administrator
bill_w4zv
--- In ham_amplifiers@..., R L Measures <r@...> wrote:
I got booted off of Topband for questioning questionable technicalWrong again Rich. I'm the moderator for Topband and I didn't boot you off...so please fabricate another story about why you voluntarily left. I thought maybe it was because you realized you didn't know what you were talking about regarding 160 meters. I got a chuckle out of your comment below about the conductivity of freshwater versus saltwater. :-) 73, Bill AG6K wrote: Howard -- Water has a dielectric constant of c. 79 whether it issalted or pure, so for RF purposes, a freshwater marsh conducts as well as a saltwater marsh. Rich, you are mixing dielectric constant with conductivity. Conductivity is the key parameter and there is a huge difference between salt water and fresh water: Surface Type Dielectric Constant Conductivity (S/m) Fresh Water 80 0.001 Salt Water 81 5.0 73, Bill W4ZV P.S. Figure R3 of 47 CFR 73.190 of the Commission's Rules contains a map of the estimated effective ground conductivity in the United States. This data is used to predict the propagation of AM signals across the United States. A higher ground conductivity indicates better AM propagation characteristics. The maps below show that the ground conductivity in the U.S. ranges between 0.5 and 30 millimhos per meter. The conductivity of seawater is 5,000 millimhos per meter, resulting in the best propagation of AM signals. (5,000 millimhos per meter is identical to 5.0 Siemens per meter...de W4ZV). |
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Need schematic or transistor data (for Henry SS amp)
GGLL
I'm searching for a solid state amplifier circuit, a Henry model C130A30 (for VHF FM). The one I have seems to have been modified, I see some resistors strangely connected both at base and collector; also after an extensive search (Google, Alltheweb, data sheet pages, and so) I did not yet found nearly a bare specification of the transistor used. Input is specified in the range of 20..40 Watts, and output of 130 Watts, and as I see it, the circuit consists of a resistive input attenuator, then follows a first stage with a CD-4778, which drives three CD-4778 (yes, the same) in parallel. All four are B-E open. It has a nice LPF at the output. Very good components with the exception of the above stated resistors.
Thanks in advance Best regards Guillermo - LU8EYW. |
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Re: Can Grid Dissipation in metal GG triodes be increased ????
Peter Voelpel
Jim,
Grid dissipation is measured by ohms law, grid voltage by grid current. Since the grid is at ground, you just measure the catode voltage with a scope. For calculation of efficiency you have to deduct the drive power first in GG, about 70% of the drive power is seen as output power. Drive power is not lost totally as with GK. If both capacitors of your input network are the same value you have no transformation, you will have 50 ohm input from the transceiver and 50 ohm output to the cathode side. I would expect the cathode impedance smaller at that power, probably 30-40 Ohms. I use that tunable pi-network on my 3CX3K amp, but used a smaller capacitor on the ouput then on the input. My coil is switched as well. I would like to use ganged capacitors there and ganged with a roller at the same time, should work with that low circuit Q. Any idea of the price of the 4?H roller by multronics? 73 Peter --- In ham_amplifiers@..., "craxd" <craxd1@> wrote: ### The next trick is how to calculate the grid diss ? ### What we see is with 800 w of drive... output is 11,500plate current @ 6800 vdc under load..... all with a dead cxr. BTW... Multronics still |
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Re: Need schematic or transistor data (for Henry SS amp)
craxd
Guillermo,
Is the resistors in mention connected across the base and collector of each transistor? If so, someone could have been trying to add feedback to the transistors. Generally though a capacitor is in series with the resistor and the resistor-capacitor is connected across each collector and base. The cap blocks the DC at the collector from going to the base. If it had a +DC voltage from the collector going to the base, you would most assuredly have some burnt out transistors. The RF input attenuator in that amp is probably made with resistors too. Is it possible it could be these? Best, Will --- In ham_amplifiers@..., GGLL <nagato@...> wrote: C130A30 (for VHF FM). The one I have seems to have been modified, I see someresistors strangely connected both at base and collector; also after anextensive search (Google, Alltheweb, data sheet pages, and so) I did not yet foundnearly a bare specification of the transistor used. Input is specified in therange of 20..40 Watts, and output of 130 Watts, and as I see it, the circuitconsists of a resistive input attenuator, then follows a first stage with aCD-4778, which drives three CD-4778 (yes, the same) in parallel. All four areB-E open. It has a nice LPF at the output. Very good components with theexception of the above stated resistors. |
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Re: Censorship/Administrator
This is all I know on the matter Rich, however I suppose
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it could have happned in a car. 73 Jim SM2EKM ------------------------------------------------------------- R L Measures wrote: On Sep 21, 2006, at 12:24 AM, Jan Erik Holm wrote:Bill Fisher W4AN committed suicide on April 4 2004.Thanks, Jim. Was the story about him dying in a car crash true or just a coverup? |
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YC-156 amp
Jim,
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Grid drive I suppose? In GG I would guess with 200W drive maybe 5-6 kW, or? Im planing to replace my 2x4-1000As with a YC-156, I think its a ideal tube. As soon as I can get hold of a good one at a decent price, would be a quick swap. However it will be GG. The 4-1000A is a pain in the rear end and Im getting to old to struggle with them. 73 Jim SM2EKM ----------------- pentalab wrote: ### These YC-156's [and YC-172's] are a huge bang for the buck. 200 w drive = 10kw + out. No socket required. $400.00 ### after messing about with multiple tube linears in the Later.... Jim VE7RF |
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Re: Drake L7
I agree with Will. Why rebuild, I would just fix whats
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broken and continue to use it. 73 Jim SM2EKM -------------------- tm303 wrote: I have obtained a Drake L7 amp from an estate. It had lightning |
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Re: YC-156 amp
Mike\(W5UC\) & Kathy\(K5MWH\)
开云体育Jim, more years ago than I can remember I built a 4-1000A GG amp.? It was ok, but hard to drive. At that time I had a HT-37.? I came upon a 3-1000Z, which can be plugged right into that same socket.? With 75 watts from the HT-37 I could drive the 3-1000Z WAY beyond legal limit on 80 meters, and it performed well up through 10 meters.? It was stable and a very nice amp.? I still wish I had not sold it. ? 73, Mike, W5UC
The 4-1000A is a pain in the rear end and I?m getting
to old |
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Re: Censorship/Administrator
On Sep 22, 2006, at 1:00 AM, Jan Erik Holm wrote:
This is all I know on the matter Rich, however I supposeThanks, Jim. RIP, Bill Fisher. R L MEASURES, AG6K. 805-386-3734 r@... |
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