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Re: 4CX1500A
David C. Hallam
All boat anchors here. Either a Hallicrafters HT-32B or Johnson Invader 200
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will be used. David -----Original Message----- |
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Re: 4CX1500A
What kind of exciter are you using?
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Jim SM2EKM ------------- David C. Hallam wrote: 3. I could reduce the drive by turning down the audio gain but really don't |
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Re: 4CX1500A
David C. Hallam
Rich,
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In regard to your suggestions of increasing the screen voltage to 750V or turning down the drive, these are my problems. 1. The screen, bias, and HV supplies are already built. The screen supply is 550V zener shunt regulated. I don't think the transformer has the output to increase the voltage by any significant amount, i.e., more than 50V or so. I could run some tests and see. 2. The bias supply would operate at -170V, but I don't think it has enough head room to supply the necessary voltage to bias the tube to cut off in stand by with 750V on the screen. In stand by it puts out about -220V. In addition to supplying the grid bias, I use it to hold in a relay that operates the relay for HV and screen primary power. That way if the bias fails for any reason, HV and screen voltage are removed from the tube. 3. I could reduce the drive by turning down the audio gain but really don't want to operate that way. 4. The exciter's carrier suppression is degraded if I turn down the RF drive. David -----Original Message----- |
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Re: 4CX1500A
On Dec 22, 2006, at 7:50 AM, David C. Hallam wrote:
Rich,Correct, but since it takes 170v peak RF V to drive the grid from ¨C 170v up to 0v, the higher the grid terminating R, the leas RF power will be needed to reach 0v. It takes +105v-pk of RF drive to overcome ¨C105V of grid bias. Why not use more screen V ? Why not turn down the power output, David ? R. L. Measures, AG6K, 805.386.3734 r@..., rlm@..., www.somis.org |
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Re: VE7RF amp
Garry
Ditto Jan,
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Couldn't agree more! And he takes nice, detailed pictures too! Merry Christmas & Happy New Year to you and to all!! Garry - WR4R Jan Erik Holm wrote: Since I have forgot/lost my Yahoo password/ID and the |
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Re: 4CX1500A
David C. Hallam
I would really like to keep the exciter looking at 50 ohm so the amp could
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be switched in and out without retuning. David -----Original Message----- |
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Re: 4CX1500A
"Robert B. Bonner
Use ALC that would control exciter power. BOB DD
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Sent From Mobile Device -----Original Message-----
From: "David C. Hallam" <dhallam@...> Date: Fri, 22 Dec 2006 10:50:18 To:<ham_amplifiers@...> Subject: RE: [ham_amplifiers] 4CX1500A Rich, So what you are saying is that it really doesn't matter from the tube's input impedance stand point what value of resistor I use. I am running 3KV on the anode and 550V on the screen. According to the constant current curve, -105V should give me 250 mA ZSAC or 50% of the max dissipation, so I need about 95V of drive across the resistor. Jerry Sevick's W2FMI has a trifilar wound 2:1 transformer supposedly good for 150W continuous. However, it is only flat up to 25MHz. The same transformer with a slightly different tap position for 2.25:1 is supposed to be good up to 30MHz. If I go to the 4:1 and use a 200 ohm resistor, I have to look at an attenuator for the exciter to keep from overdriving the amp. David -----Original Message----- Yahoo! Groups Links |
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Re: 4CX1500A
David C. Hallam
Rich,
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So what you are saying is that it really doesn't matter from the tube's input impedance stand point what value of resistor I use. I am running 3KV on the anode and 550V on the screen. According to the constant current curve, -105V should give me 250 mA ZSAC or 50% of the max dissipation, so I need about 95V of drive across the resistor. Jerry Sevick's W2FMI has a trifilar wound 2:1 transformer supposedly good for 150W continuous. However, it is only flat up to 25MHz. The same transformer with a slightly different tap position for 2.25:1 is supposed to be good up to 30MHz. If I go to the 4:1 and use a 200 ohm resistor, I have to look at an attenuator for the exciter to keep from overdriving the amp. David -----Original Message----- |
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Re: 4CX1500A
On Dec 22, 2006, at 5:11 AM, David C. Hallam wrote:
Does anyone have information as to the approximate input impedanceD. -- The resistive component of the grid input Z is well over 1,000,000-ohms in AB1, and the reactive component is 78pF. With 750V on the screen, it takes c. ¨C170 grid V to establish a ZSAC of 200mA. If the grid is terminated in 200-ohms, 73w-pep is needed to drive a 4CX1500A. With a 50-ohm termination, 289w is needed. I50 to 200 ohm un-uns are a piece of cake, but a 50 to 100 ohm un-un probably isn't very easy to make. cheerz R. L. Measures, AG6K, 805.386.3734 r@..., rlm@..., www.somis.org |
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4CX1500A
David C. Hallam
Does anyone have information as to the approximate input impedance of a
4CX1500A for the proper value of a passive grid resistor for this tube? I need about 100 ohm to get sufficient grid drive, i.e., 95 volts, so will have to use a balun to maintain 50 ohm for the exciter. I just wondered how close a 100 ohm resistor would be. David KC2JD |
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Re: Tube rebuilder
ad4hk2004
Well, Santa brought me an $800 xmas present... I removed the HV lead
from the 3CX1200D7 and cooked the filament at 7.26 volts for 6 minutes... Eimac had suggested 7.5 volts for 5 minutes but 7.26 was all I could get without going looking for the 220 Variac and unsoldering a bunch of wires inside the Henry... For a moment I started to pull the tube out on the bench and cobble up a test jig, then basic laziness caught up with me <I had already put in a 12 hour day, so cut me some slack> Anyway, post toasty, the tube puts out 1700 watts for 74 watts of drive and the grid current right on 200 mils.. Before the toasting it put out 1100 watts with 48 watts of drive hitting 200 mils on the grid... So for the moment all is well... Who knows how long the tube will work... I have reset the filament to 6.6 volts for running, which is right at the upper limit per Eimac... I did try it at 6.3 volts and saw a 120 watt drop on output... So the filament emission current is sagging... At full output I am seeing the input swr at 1.6:1 through the input transformer... I was going to calculate the grid dissipation then realized I don't know the Grid to cathode voltage under load... We tried taking a DC measurement off the filament to ground under load, but with the AC superimposed on the cathode current I don't trust the numbers I see, especially since there is a half volt, or more, difference from one side of the filament compared to the other... So I don't know how to calculate the dissipation unless I just assume that voltage from the Eimac tube curves... Anyone? denny / k8do |
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VE7RF amp
Since I have forgot/lost my Yahoo password/ID and the
lot for my ordinary email address I havent been able to sign in and view the pictures. Finaly I signed in with a new Yahoo ID and it was nice to be able to see the pictures. I must say that VE7RF sure built a very nice amplifier!! Sure would have been nice if my junk amps was that nice. Maybe I should post some pictures just to show that some stuff isnt nice looking? But it works just fine. Merry Christmas and Happy New Year to you all Jim SM2EKM |
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Re: Tube rebuilder
ad4hk2004
I know what I paid for my 3KU brand new... When I look at the quality
of the materials, the hand made switching solenoids in the tank circuit, the silver plated 1/4" tubing roller inductor the size of your thigh, the thick aluminum cabinets, the milspec connectors and the cable to the control head, etc., they had to have been barely breaking even given their obvious material and labor costs... The amp is built hell for stout... I suspect that losing their lease gave them a graceful way to staunch the bleeding... I understand where you are coming from Rich on the untuned input, yet the amp always gets compliments on the rare occasions I get into a roundtable on phone with the guys... And even Eimac during my phone call to them complimented Henry for doing innovative things that no one else in the industry did... I have been through several Henry amps, 3K and 4K, and the last few years they were in business when I called to talk to the techs no one there spoke english anymore... And the answers I got made me suspect they were winging it, rather than really knowing the amp... LA is a ferociously expensive place to live and to do business - and California taxation will spin your hat... Any tech who had electronic skills could demand $25 or $30 an hour, and get it... Henry's overhead had to be eating them... Had I been running the company I would have moved it to Laramie Wyoming, or Depuke Ioway, in a heart beat... The remaining 3K Classic I have, with 3-500's, will sit there and pump out 1500 watts of CW all day long... Of course, the plates glow like a xmas tree doing it, but they seem to hang in there... denny / k8do |
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Re: Tube rebuilder
On Dec 20, 2006, at 1:40 PM, pentalab wrote:
--- In ham_amplifiers@..., R L Measures <r@...> wrote:A broadband input plus g-g tells me that these guys are/were not very knowledgeable.wrote: Most Hams who build electron tube amplifiers probably realize that the input-Z of a g-g stage typically fluctuates from a few tens of ohms at the negative peak of the driving cycle to a virtual open circuit at the positive peak. Thus, a flywheel / tuned circuit is required to even out the input-Z out and keep the exciter happy.any of... Sounds appropriate. chortle cheerz, Jim R. L. Measures, AG6K, 805.386.3734 r@..., rlm@..., www.somis.org |
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Re: Tube heater current
GGLL
Well, today I measured the Penta 6JB6 heater current, which resulted 1.5A. or 25% more than data sheet stated (1.2A). The rig is working with two Pentas (120 watts out), and I added some resistance to compensate heater currents (agreed this with the owner, because a new 6JB6 in our local market costs around 63 US$, so to change all would add nearly 200 US$ to the overall cost).
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A last comment, about these sweep tubes procedence; 11 years ago or so, a friend (my radio elmer, now SK) which worked also repairing radios, had a similar experience, with the exception that the owner of the radio in his workbench bought the three replacement "12JB6" in a USA electronics market, in boxes with a "Radio Shack" brand printed. My friend put them in that TR-4C, with no results. After a close inspection, he found that the 12 number was printed over an erased 17 on all three tubes. They were really 17JB6. Best regards Guillermo - LU8EYW. Robert B. Bonner escribi: I was a Drake technician, put myself through college doing it. |
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Re: Tube rebuilder
pentalab
--- In ham_amplifiers@..., R L Measures <r@...> wrote:
wrote: long impedencetalkHenry hewith Eimac yesterday and after going over the symptoms on myhas me convinced that the tube has changed its input Pi- ### where have u been ? yes... it's GG. Now u know why Inetwork?RICH SEZ.... Does it use g-g config? collect amplifier manuals. Weinspected,not the of allhaveeyeballs,spent considerable time and effort using VOM, LC meter, MK-Ietc. to prove the mechanical and electrical charateristics indirectlydiodes,relays, RF cables, caps, inductors, resistors, transformers,accurate,and on, and on... We found that the Henry manual is not 100%but the errors are easily spotted and not significant if you 1100heatedvoltagecathode on a 3CX1200>chortle milswattswith 48 watts in and the grid current is right at the 200 any of### well rich.. I guess eimac is right... since his input swrlimit... Did Henry Radio get out of the amplifier business?the 3k/8 k ultra's were ever dead flat.... with that broadbandedRICH SEZ...There is no such thing as a broadbanded input for g-g. ### agreed. The 'broadband tuned input' is a one off disaster. they used 2 x xfmr's.. back to back.. on the 8 k ultra... and simply stepped the Z way up... then stepped it right back down to 50 ohms. ... on all bands cept 25-30 mhz... where they stepped it up.... but didn't step it back down as much... more like 75 ohms. ### Henry radio anounced 2 yrs ago.. that they lost their lease at the LA factory where they been for the last 40 yrs. They are OUT of the HF amateur amp business... and I believe also the commercial/military HF amp business. They still are in the solid state VHF/UHF amp business. Dunno, if they still support HF amps.... with various bit's and pieces or not. Too bad... they did make some excellent products over the years... like the 4 k ultra. I bought one of their 10 kw ccs LP filters just a few yrs ago.... with a 33 mhz cut off.... built like a tank.... with 7-16 DIN connectors... and bottom plates were 3/16" thick anodized AL... and big 1/4" silver plated tubing coils.. Plus 8 x HT-57 NPO caps in em. ### They also made excellent attenuator's.... in 1-2-3-4-5-6 db increments... in both 35/100+ watt versions... 50 ohms in/out. They shoulda just relocated the entire factory... too bad... end of an era. Rumour has it that Rube Goldberg worked there at one point. Later... Jim VE7RF
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Re: Heatsink relationship
Robert B. Bonner
Bill it all has a lot to do with CONDUCTIVITY and stability. Whether it is
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electrical or thermal conduction. Copper has a large availability of free electrons. The molecules freely exchange them. Other substances are not quite so loose. Chemistry is total mad science. BOB DD -----Original Message-----
From: ham_amplifiers@... [mailto:ham_amplifiers@...] On Behalf Of Bill Turner Sent: Wednesday, December 20, 2006 10:12 AM To: ham_amplifiers@... Subject: Re: [ham_amplifiers] Heatsink relationship Sorry Hal, but your reply was totally incomprehensible. You went off about fractals, space blankets, waterbeds and electric bills without answering my question regarding density of "stuff", specifically why some less dense "stuff" is actually a better heat conductor and some more dense "stuff" is not. Try again if you like. Bill, W6WRT Yahoo! Groups Links |
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Re: Tube heater current
pentalab
--- In ham_amplifiers@..., "Robert B. Bonner"
<rbonner@...> wrote: KWM-380 showed up on the doorstep we tested both and said, what theF'enheimer are these guys thinking?### The TR-7 wsn't too bad. The KWM-380 was pure junk imo. The mating outboard processor for the 380 never did work right. Funny thing though... in the QST write up for the 380.. they ran it into the ground. Meanwhile, in the same issue... their is a 380 full page colour add on inside back cover ! That was the very LAST ad.. that Collins ever ran in QST. ## It was a well know fact back then.. that manufacturer's of ham gear.. when sending a product sample to the ARRL lab.. to be tested in the same lab... would be sending off basicly one off products... where all the 10% resistor's were hand picked.. and matched.. and under 4% tol.... each stage was precisely aligned, and one off components used, etc.... basicly.. the best one ever built. ### The ARRL finally smartened up.. and sent in buyer's off the street... and they bought XXX from AES... HRO, etc... or were ordered.. then shipped via UPS [read bashed outa alignment]... THEN they do the various tests. Put my pocket protector on the back of the bench and said have a nice day.gone by the time it showed up. I have zero experience with them, however theL4 series I could build in my sleep. I always had a huge supply of parts andthe parts bins helped me with my original building projects.day. I looked at it and said? Whats this for? Ceramic, huh, looks likeit could take some power... OH hey Brand New L4B ha.. Hey anybody need oneof these? Ought to be worth a couple hundred now.### It's a simple 4 x section 440 pf per section broadcast variable... that u can get from fair radio for $16.00. They used 2 x sections on 20-10m... all 4 x sections on 40m... and padded it on 80m with a fixed 700 pf mica. come out. ### Highly agreed. Ever see the Icom 701 ??? Tuned in 100 hz increments !! You should hear how cw sounds that way.. tuning across the bands. Icom has been making pure junk ever since. The 756 pro 1-2-3 is a failure, imd ridden mess. "but it's digital" screams the newbie. The DSP is a joke in em.... they are simple audio DSP chip sets.. used at low freqs.. at the wrong end of the xcvr. I laughed when I saw their ad for a '32 bit floating point dsp chip ' My Behringer EQ uses a 40 bit/96 khz... per channel dsp chip... and a 32 bit 96 khz per channel dsp for the misc stuff... and they are dirt cheap. Imo... installing dsp at the back end of the xcvr just enhances profits.. since no more xcvr's made with real xtal/collins mech filters. Heck... after 30 yrs... icom /yaesu finally figured out "roofing" filters... kinda late... Rob Sherwood had it figured out 30 yrs ago... and still has a better set up. The roofing filter has to pass BOTH sidebands... and my modified R4C used a separate 2.0 khz xtal filter for each ssb... and a 600 hz cw filter for LSB only [since the radio tranceived on lsb]. Fast forward 30 yrs... what do we have now? Icom 7800/yaesu 9000 with a 3/6/12 khz roofing filter in front end... which is still a lousy set up... since they all straddle zero beat. .. then they add the $5.00 "dsp" at the back end of the xcvr ! Now Raytheon, etc all.. do it right.. and at least put the DSP at the front end of the radio. They have DSP chips that work out to almost 500 mhz... so why not use em. later.. Jim VE7RF |
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Re: Tube heater current
Robert B. Bonner
Hey Gary,
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Heading out the door on the way to grad school. The TR-7 showed up on the doorstep, right about the same time the KWM-380 showed up on the doorstep we tested both and said, what the F'enheimer are these guys thinking? Put my pocket protector on the back of the bench and said have a nice day. About all I ever did with the L-7 is look at one, (pretty) I was gone by the time it showed up. I have zero experience with them, however the L4 series I could build in my sleep. I always had a huge supply of parts and the parts bins helped me with my original building projects. Hey I just found an L4B loading cap new in my parts bin the other day. I looked at it and said? Whats this for? Ceramic, huh, looks like it could take some power... OH hey Brand New L4B ha.. Hey anybody need one of these? Ought to be worth a couple hundred now. Anyway, It was the beginning of the worst streak of radios to ever come out. All the first runs of solid state, man the manufacturers really didn¡¯t have a clue. The NEW KENWOOD, TS-POS whatever, I was the first to find out if you put the Power Supply on the wrong side of the radio (The factory always sat it on one particular side) would induce MASSIVE HUM into the radio. You should have "over heard" that phone call with Kenwood it was a once in a lifetime experience. The next radio I got in had a mimeograph sheet slipped in the manual. That was because of me if any of you ever owned that Kenwood. I cant even remember the NUMBER the full sized Successor to 830, 530 etc... I have a real mean streak in me when people/companies have NO humility. I wasn¡¯t the company owner, I wasn¡¯t the department manager, but I was the TECHNICIAN and a pretty good one too. I had a massive out of store Collins trade that was bigger than the dealers. It really made the manager mad. My Frat room was stocked full of Guns and S-lines. BOB DD -----Original Message-----
From: ham_amplifiers@... [mailto:ham_amplifiers@...] On Behalf Of Garry Sent: Wednesday, December 20, 2006 8:38 AM To: ham_amplifiers@... Subject: Re: [ham_amplifiers] Re: Tube heater current Hi Bob, Were you with Drake when the L-7 came out? Thanks, Garry - WR4R Robert B. Bonner wrote: the tubes.was considerable difference in height of tubes manufacturer to manufacturer.a considerably smaller package.<mailto:ham_amplifiers%40yahoogroups.com> Subject: Re: [ham_amplifiers] Re: Tube heater currenthave lot
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