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Re: Building my first amplifier. Where to start?
Guys,
Thanks all for your responses, lots of food for thought. I think the GU5b will not do what I need/want. It will need 100w drive for about 1kw output, so not enough gain.? The gs35b suggested here and by someone else looks like a great triode as an option. 100w drive should easily produce 1.5kw output.? The filament is easy to deal with too etc. it's not expensive which is another bonus. So let's call that option 1. Option 2 then, is more complex. A tetrode. Sure I was initially put off with the extra circuits required, but after reading some more and looking at f1grv's site, they look good. He supplies the control and protection boards, so that makes life much more easy. He is suggesting for upto 1.5kw with 100w drive use a triode like the gs35, or for real power, over 2kw, use a tetrode. His tube of choice is the gu78b which he says is happy at 3kw, and can be pushed to 5kw, which is more than I need or want. Also that tube is expensive and less available.? So I was thinking a gu43b, which is very "cheap" at about 100 bucks, very available,, easily filament supply, and can easily do 1.5kw output. Can even be pushed to 2kw, which was/is? my original goal. But what about running a pair, for 2kw all day, with 3+kw peak ssb..? I have the anode supply capacity..? Oh boy. Down the rabbit hole i go.? Thoughts. Cheers guys.? |
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Re: Building my first amplifier. Where to start?
Is the GU5B a high mu triode ???? ?( MU at least 130 or higher).? If not, you are DOA right there.? ? Low mu triodes can't be used in GG (cathode driven service).? Reason is, they will draw stupid amounts of idle current, which then requires stupid levels of bias.... which means silly amounts of drive power to overcome the bias.? ?You can tell from the constant current curves if the tube is low or high mu.? Find on the graph what the idle current is with zero bias.? ?If it's like 8-20 amps, it's low mu.? ? What's the input Z of a single GU5B ?? If it's not stated, I have come up with an easy method to determine it quick like.? ? Don't start any HB? amp project unless you have known good tubes.? ?You only need ONE tube for your proposed amp.? ?Make damn sure you have at least 2 x known good tubes, one for the amp, and at least, at a minimum, one good spare...and preferably several good spares.? ? Any GG amp is just a PI tuned input.....and a PI output.? ?And both those are both? designed using GM3SEK's? PI? spreadsheet.? ?The tuned input info / values in ORR's radio handbook are out to lunch, not even close to reality.? ?These days, I don't mess with bandswitched? PI networks for the tuned input.? Instead it's just a pair of broadcast air variables and a tapped coil...and input swr is always dead flat.? ?The tubes grid to cathode C is directly in parallel with the C2 cap on the tuned input..... as is the stray C? from each? wire on the fil choke..to chassis.....at the cathode end of the fil choke.? ? The kw PI net is easy to design.? ?But we have to know the loaded B+ and plate current to determine plate load Z.? ?Plate choke is simple.? The latest ferrite loaded designs are bomb proof.? A 20 amp fil choke is a non issue.? ?Even a 160 amp fil choke is a non issue.? By making it a 80-10m amp, instead of a 160-10m amp simplifies everything by a bunch.? ? The grid and plate current metering has not changed in 50 years....simple setup.? ?TR relays are also a non issue.? |
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Re: Building my first amplifier. Where to start?
I would use one and keep the other as a spare, in terms of heat, just the
250W of filament power each will keep the shack warm enough in winter! If
you directly ground the grid and have the input tune adjustable that
should make for efficient driving.
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Mike VK2AMF / G3XEF ? At 07:41 PM 24/12/2023, you wrote: Thanks everyone for replying. I live in Northern Ireland, call sign GI0UTE.? I'm not aware of any qro builders nearby.? I have ordered a few books as have been suggested and have stared reading some of the web links posted. There is plenty to take in! |
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Re: Building my first amplifier. Where to start?
开云体育Love it! I run a YC156 in my homebrew amp.? It's way way way overkill but at 4.3KV, it runs limit power without trouble and I don't have to worry about breaking the tube.? I've got a number of now-dead amps that were killed in RTTY contesting; death by a variety of things.? But the YC156 is pretty much bullet proof save for needing to keep an eye on the grid current.? At the low B+, it's the limiting factor from a tube risk standpoint.?? A buddy of mine convinced me to buy his 15K because it will sit
in the same socket and would look great.? I put it in to make sure
it was operational, which it was, but it's operationally no
different than the YC156 and with the lid on, it's hard to see the
cool look feature.? The funny part is that since I got the FLEX PGXL which will run
So2r and does just fine under RTTY whipping conditions, I hardly
use the old tube amp now.? The Flex is just a lot more convenient. 73/jeff/ac0c alpha-charlie-zero-charlie On 12/24/2023 9:37 PM, HaL Mandel
wrote:
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Re: Building my first amplifier. Where to start?
开云体育Hi Jeff! ? Merry Christmas. ? I can just imagine two (2), 3CX15,000A7’s, in Push-Pull, ? Modulated with two (2), 3CX15,000A7’s. ? Riley Hollingsworth would personally lead the arrest, complete with Thompson .45’s. ? Some years ago, the main power transformer was robbed from the Beverly-Ann Coal Tipple in David, Kentucky. ? They got a 20,000 pound hunk out of the mine with two feet of mud everywhere, and nobody knows a thing… ? Best, Jeff. ? Hal |
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Re: Building my first amplifier. Where to start?
开云体育Hal, If you need a spare 15K, I've got a NIB one here that needs to
find a new home.? 73/jeff/ac0c alpha-charlie-zero-charlie On 12/24/2023 4:11 PM, HaL Mandel
wrote:
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Re: Building my first amplifier. Where to start?
开云体育Yes Jeff. "Took the words . . . . . ." 73, Alek VK6APK.
On 25/12/2023 1:09 am, Jeff AC0C wrote:
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Re: Building my first amplifier. Where to start?
开云体育Steve, ? In calculating the Anode Iron requirement for Class AB1, the beast would weigh 565 pounds. (25 KVA). (3CX15,000A7) ? But that was 8 years ago, and now, and now: “Uh – Uh.” ? Yon beasties are for the Young’uns. ? Hal W4HBM |
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Re: Building my first amplifier. Where to start?
开云体育Here at my off-the-grid, solar-charged, battery-powered QTH, I'd need a submarine fulla good batteries just to run the heater on onna those, let alone leaving a brick on the key all day. ===8-O Steve, K0XP
On 12/24/2023 12:59 PM, HaL Mandel
wrote:
--
See my QRZ.com page at |
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Re: Building my first amplifier. Where to start?
开云体育Hullo Bill, ? So you’re squeamish about 20 or 40 amps on the heaters, aye? ? Well, wait ‘til ye graduate to Valves with Lifting Handles! ? Some of those babies need 165 amps to warm them up. ? Rich Measures fooled around with Handles. ? He sure did.? But he remembered to start each of his Clandestine Jobs with Step: One (Budget). ? I’ve been sitting on three monsters currently in the parts shed. Got the tubes, etc. But cannot meet Step: One any more. ? Hal W4HBM |
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Re: Building my first amplifier. Where to start?
开云体育A single GS35b is a nice choice as well per your original power
objectives.? And at 4.7KV it will have pretty nice efficiency.? I
ran one here at 4.4KV for years.? Minimal heater current
requirements.? A socket can be built with minimal mechanical
hassle. 73/jeff/ac0c alpha-charlie-zero-charlie On 12/24/2023 10:22 AM, bill steffey
NY9H wrote:
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Re: Building my first amplifier. Where to start?
bill steffey NY9H
开云体育20 + amps at 12 volts??? just to light up 1 tube ,,,,,???? 2
tubes would be 40+ AMPS !!!!!
On 12/24/2023 3:41 AM, desmond auld
wrote:
Thanks everyone for replying. I live in Northern Ireland, call sign GI0UTE.? I'm not aware of any qro builders nearby.? I have ordered a few books as have been suggested and have stared reading some of the web links posted. There is plenty to take in!? -- link to my QRZ listing |
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Re: Building my first amplifier. Where to start?
Thanks everyone for replying. I live in Northern Ireland, call sign GI0UTE.? I'm not aware of any qro builders nearby.? I have ordered a few books as have been suggested and have stared reading some of the web links posted. There is plenty to take in!?
I agree a single GU5b with it's 2.5kw dissipation rating should be enough to match my power needs, but perhaps two in parallel would run cooler ( run a quieter fan?), and perhaps deliver more gain? I have a 100w radio and don't really want to need to run a "driver" amplifier, so would need a gain of over 10 dB, ideally 13 ish. Not sure how that's calculated yet from tube characteristics.? I'm in no hurry, and am not tied to using this tube, so am open to suggestions.? Thanks again all, and merry Christmas! Des, GI0UTE? |
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12 KW CCS ON 160-15M...USING THE 3CX-6000A7... PART 9
Here, the paralleled pair of Jennings? RJ2B output vac relays are installed.....along with the 7-16 DIN output connector.
Also installed is the 1/2" silver plated tubing coil, used for 20 + 15m.? ?Also installed is the hb? 3/8" tubing coil, used for? 80+40m.? The hb cu discs ?are cut and installed for the vac tune and vac load caps.? The? hb 1/4"? ?tubing coil (used for 160m) is wound, but not yet installed, nor the 100mm diam Draloric plate block cap.? On the rear apron,? you can also see the pair of 100 amp, superior electric ...'supercon connectors', used to terminate the cables for the 7.0 vac @ 78 amp fil supply.? It's progressing pretty good.? The entire B+ supply has yet to be built... but is a straight forward project, since it's already been done several times before.? ? |
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Re: Building my first amplifier. Where to start?
Stated he was in The UK. Mike
On Saturday, December 23, 2023 at 06:20:08 PM EST, Dave w6de <w6de@...> wrote:
You don’t say where you are located or provide a call sign so those of us replying don’t know where you are for parts recommendations. ? The Eimac book “Care and feeding of power grid tubes” book has a lot of good information.? This book should be in all Amplifier Builder’s and Modifier’s libraries. ? There is a copy on-line from CPI (owners of Eimac) in six sections.
? Start by looking at Section-3 “Electrical Design Considerations.? For instance, In section 3 it has sections on Lead Length, Filament Bypassing, Keying, and more.? Section 3 also talks about Class A, AB, B, and C amplifier characteristics. ? If you find it useful.? I’d suggest buying a book on-line.? eBay USA has several for sale. ? ? 73, Dave, w6de ? From: [email protected] <[email protected]>
On Behalf Of desmond auld via groups.io
Sent: 23 December, 2023 10:56 To: [email protected] Subject: [ham-amplifiers] Building my first amplifier. Where to start? ? Hi guys, I have been subscribed to this list and reading messages for some time, but I believe this is my first message, so hello all. I am a ham based in the UK and have been interested in amplifiers for some time. I have a somewhat basic
understanding of their operation if I'm honest, and currently own a linear amps UK 811 hunter. It uses 4 off 811 tubes, and runs very well. I understand 811's are somewhat delicate, and so I tread lightly with them. |
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Re: Building my first amplifier. Where to start?
开云体育You don’t say where you are located or provide a call sign so those of us replying don’t know where you are for parts recommendations. ? The Eimac book “Care and feeding of power grid tubes” book has a lot of good information.? This book should be in all Amplifier Builder’s and Modifier’s libraries. ? There is a copy on-line from CPI (owners of Eimac) in six sections.
? Start by looking at Section-3 “Electrical Design Considerations.? For instance, In section 3 it has sections on Lead Length, Filament Bypassing, Keying, and more.? Section 3 also talks about Class A, AB, B, and C amplifier characteristics. ? If you find it useful.? I’d suggest buying a book on-line.? eBay USA has several for sale. ? ? 73, Dave, w6de ? From: [email protected] <[email protected]>
On Behalf Of desmond auld via groups.io
Sent: 23 December, 2023 10:56 To: [email protected] Subject: [ham-amplifiers] Building my first amplifier. Where to start? ? Hi guys, I have been subscribed to this list and reading messages for some time, but I believe this is my first message, so hello all. I am a ham based in the UK and have been interested in amplifiers for some time. I have a somewhat basic
understanding of their operation if I'm honest, and currently own a linear amps UK 811 hunter. It uses 4 off 811 tubes, and runs very well. I understand 811's are somewhat delicate, and so I tread lightly with them. |
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Re: Building my first amplifier. Where to start?
I have found "Valve Amplifiers Explained" by John Fielding
ZS5JF quite helpful, its published by the RSGB.
Mike VK2AMF / G3XEF. At 09:56 PM 23/12/2023, you wrote: Hi guys, I have been subscribed to this list and reading messages for some time, but I believe this is my first message, so hello all. I am a ham based in the UK and have been interested in amplifiers for some time. I have a somewhat basic understanding of their operation if I'm honest, and currently own a linear amps UK 811 hunter. It uses 4 off 811 tubes, and runs very well. I understand 811's are somewhat delicate, and so I tread lightly with them.
Mike Fleetwood |
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Re: Building my first amplifier. Where to start?
开云体育Dear Des, ? Welcome to the forum. ? You can’t do too much better than the collection Of builders and thinkers hereon. ? In the amplifier schematic you posted I wonder If the Input Network Inductor is a roller-type, And the capacitors mini-vacuum-variables? ? Oh Boy. ? Look out Surplus Sales of Nebraska! ? Best, ? Hal Mandel W4HBM |
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Re: Building my first amplifier. Where to start?
On 12/23/2023 7:09 AM, Floyd - K8AC wrote:
The older ARRL handbooks are a good source of amplifier circuits and info.? I have a 2004 Handbook with some interesting amplifier circuits.I would interject that The Radio Handbook, edited by Bill Orr and/or "Editors & Engineers", is generally much more informative than almost any of the ARRL handbooks for amplifier circuitry, in particular. Various editions are available from time to time on epay at modest prices. The RSGB handbooks can also yield some valuable insight but are generally geared toward legal-limit power levels. Seems to me that just a single GU5B will deliver the legal limit easily.Agreed... they seem rated at 3 kW per tube...?? And all of the specs I've seen indicate the tube should be installed with anode down. I would venture to say that your MOST VALUABLE "insight" would probably be to make friends with a ham/amplifier builder within driving distance who knows what they are about. Yes, easier said than done, especially these days with the older, more-experienced folks dying out left and right... On your side of the pond, for high power schtuff, G8WRB comes to mind, but I haven't heard of nor seen anything from him for years. G3SEK is another but I believe he's mostly-retired from homebrewing..?? Try doing a Yahoo search using the various high power Russian transmitting tube numbers and many other European builders will come up... some of whom are even still around!! 73, Steve K0XP |
HaL Mandel