Fw: [yccc] Followup: KM1H
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On Tuesday, December 26, 2023, 3:43 PM, Rudy Bakalov <r_bakalov@...> wrote:
----- Forwarded Message -----
From: Doug Grant <dougk1dg@...> Sent: Tuesday, December 26, 2023 at 03:38:10 PM EST Subject: [yccc] Followup: KM1H
Since nobody had any direct info on Carl's status, I drove to his house and knocked on the door today, not quite sure what to expect.
Carl's ex-wife answered the door and invited me in. She announced me to Carl, who then made his way down the stairs . We had a nice visit and yakked for about a half-hour. He knew me, and even asked how my "twin" (K1AR) was doing.
He was unaware that his ham license had expired, but at age 83, sometimes events like that slip by.
So now you know "...the rest of the story".
73,
Doug K1DG
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Re: Building my first amplifier. Where to start?
With 3 phases anode voltage will be completely different as will be the rectifier stack.
?
73
Peter, DJ7WW
?
?
?
-----Original-Nachricht-----
Betreff: Re: [ham-amplifiers] Building my first amplifier. Where to start?
Datum: 2023-12-26T18:56:37+0100
Von: "desmond auld" <desauld@...>
An: "[email protected]" <[email protected]>
?
?
?
Hal,
I might message g(m)0sek if I struggle,thanks for the advice.??
I have a 3 phase transformer with various taps. It's rated 20kva. I have tried single phasing it, and it runs ok. Less capacity obviously but it has plenty to spare. It's circa 150kg or 330lb. Depending on the configuration I have various output voltages. If needed I have 3 phase from a genset available.? Anode supply shouldn't be an issue.?
?
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Re: Building my first amplifier. Where to start?
On 12/26/2023 9:56 AM, desmond auld wrote: I have a 3 phase transformer with various taps. It's rated 20kva. I have tried single phasing it, and it runs ok. Less capacity obviously but it has plenty to spare. It's circa 150kg or 330lb. Depending on the configuration I have various output voltages. If needed I have 3 phase from a genset available.? Anode supply shouldn't be an issue. Ummm... before you settle on that monster, you might want to fire her up and measure the idling current, no-load. Then again, with some temporary load resistors across the secondary. The results just might make you wonder if you aren't mad... 8-) Steve, K0XP
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Re: Building my first amplifier. Where to start?
First thing I'd do is copy the spreadsheet and revise the dropped
Ep to no more than 2500V, perhaps 2550 at most, then design for
that reduced value. Unless you're in a commercial establishment,
with commercial-quality mains and components, Ep always seems to
drop below our best hopes? 8-/
Steve, K0XP
On 12/26/2023 8:05 AM, desmond auld
wrote:
Hal,
Yes, one of concerns is "committing" to a tube that dries up by
way of availability.? That's why the GS35 and Gu43b are on my
radar,as they seem so plentiful.? If i do get an amplifier up and
running of my own creation i will invest in many spares to keep on
the shelf and circulate every year to keep fresh ish.? The old
811's in my existing amp has are now getting relatively expensive
for a 65w dissipation tube,and the 572B's are out of hand cost
wise considering they are all now Chinese of poor/average quality,
so i understand the concern of going down a dead end.??
I have spent some time today reading, and plugging in numbers into
the wonderful G3SEK spreadsheet to calculate the values of C1, C2
and L1 in the tank circuit of an imaginary amplifier based around
two GU43b's in parallel. I have assumed some things, obviously,
like the HV will drop under load to 2700vdc from circa 2900vdc.? I
have modified the spreadsheet to have a tab for each band, 10-80m,
that i'm interested in, and also a summary sheet with what a
beginner such as myself thinks is important.? i would be VERY
grateful if those that know what they are doing could critique my
assumptions and the outputs.? Spreadsheet attached , with summary
copied in below.
Does anything look way out of wack in my assumptions, or not
practically possible in my outputs?
I went looking in my "capacitors for the big amplifier" box and
have a good section of high voltage door knobs, and two beautiful
vacuum variables, that i could use.? One is very large, 25KV rated
15-350pf, and another is smaller 15-90 pf 40Kv rated.? I had
almost forgot i had these things!? I'm getting quite excited. :)?
Has anyone any good links for winding tank coils with calculations
etc??
Alex from UR4LL has the GU43b tubes in stock and i am talking to
him at the moment about purchasing some along with some other
parts i may need.? He has a beautiful EImac 4cx 10,000 for sale if
anyone is interested.? I'm not man enough :)
Thanks guys
--
See my QRZ.com page at
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Re: Building my first amplifier. Where to start?
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Re: Building my first amplifier. Where to start?
Hi Desmond,
?
What is your Ham Radio Call Sign?
?
Thanks,
?
Walter
KR4HV
?
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From: [email protected] <[email protected]>
On Behalf Of desmond auld
Sent: 26 December, 2023 12:48 PM
To: [email protected]
Subject: Re: [ham-amplifiers] Building my first amplifier. Where to start?
?
Peter,
Thanks for the advice. Ok, I understand the issue can be stray capacitance and inductance?
I see this project happening in stages, eg build with what I have and some extra pieces to prove the concept and learn. Then refine the build and make tidy, using more suitable components etc.? Never make the prototype the final example is my thinking.
Thanks, des.?
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Re: Building my first amplifier. Where to start?
Hal,
I might message g(m)0sek if I struggle,thanks for the advice.??
I have a 3 phase transformer with various taps. It's rated 20kva. I have tried single phasing it, and it runs ok. Less capacity obviously but it has plenty to spare. It's circa 150kg or 330lb. Depending on the configuration I have various output voltages. If needed I have 3 phase from a genset available.? Anode supply shouldn't be an issue.?
|
Re: Building my first amplifier. Where to start?
Peter,
Thanks for the advice. Ok, I understand the issue can be stray capacitance and inductance?
I see this project happening in stages, eg build with what I have and some extra pieces to prove the concept and learn. Then refine the build and make tidy, using more suitable components etc.? Never make the prototype the final example is my thinking.
Thanks, des.?
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Re: Building my first amplifier. Where to start?
Des,
?
GM3SEK relocated to Scotland some years ago.
I believe he will still correspond with amateurs
who face design complications.
?
I still would like to know what your power supply
might consist of.
?
The Anode trannie is so important. The last
thing you want to face is the voltage sag while keying.
?
So have you made your decision? I believe you
mentioned having a retired “Pole pig.”
?
They are so worthwhile.
?
Hal
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Re: Building my first amplifier. Where to start?
I would use capacitors as small as possible, not those monsters.
You want all connections within the tank circuitry as short as possible.
?
I have good experience winding coils by using the program PIEL:
?
73
Peter, DJ7WW
?
?
?
?
-----Original-Nachricht-----
Betreff: Re: [ham-amplifiers] Building my first amplifier. Where to start?
Datum: 2023-12-26T17:05:56+0100
Von: "desmond auld" <desauld@...>
Does anything look way out of wack in my assumptions, or not practically possible in my outputs?
I went looking in my "capacitors for the big amplifier" box and have a good section of high voltage door knobs, and two beautiful vacuum variables, that i could use.? One is very large, 25KV rated 15-350pf, and another is smaller 15-90 pf 40Kv rated.? I had almost forgot i had these things!? I'm getting quite excited. :)?
Has anyone any good links for winding tank coils with calculations etc??
?
|
Re: Building my first amplifier. Where to start?
Hal, Yes, one of concerns is "committing" to a tube that dries up by way of availability.? That's why the GS35 and Gu43b are on my radar,as they seem so plentiful.? If i do get an amplifier up and running of my own creation i will invest in many spares to keep on the shelf and circulate every year to keep fresh ish.? The old 811's in my existing amp has are now getting relatively expensive for a 65w dissipation tube,and the 572B's are out of hand cost wise considering they are all now Chinese of poor/average quality, so i understand the concern of going down a dead end.?? I have spent some time today reading, and plugging in numbers into the wonderful G3SEK spreadsheet to calculate the values of C1, C2 and L1 in the tank circuit of an imaginary amplifier based around two GU43b's in parallel. I have assumed some things, obviously, like the HV will drop under load to 2700vdc from circa 2900vdc.? I have modified the spreadsheet to have a tab for each band, 10-80m, that i'm interested in, and also a summary sheet with what a beginner such as myself thinks is important.? i would be VERY grateful if those that know what they are doing could critique my assumptions and the outputs.? Spreadsheet attached , with summary copied in below.  Does anything look way out of wack in my assumptions, or not practically possible in my outputs? I went looking in my "capacitors for the big amplifier" box and have a good section of high voltage door knobs, and two beautiful vacuum variables, that i could use.? One is very large, 25KV rated 15-350pf, and another is smaller 15-90 pf 40Kv rated.? I had almost forgot i had these things!? I'm getting quite excited. :)? Has anyone any good links for winding tank coils with calculations etc?? Alex from UR4LL has the GU43b tubes in stock and i am talking to him at the moment about purchasing some along with some other parts i may need.? He has a beautiful EImac 4cx 10,000 for sale if anyone is interested.? I'm not man enough :) Thanks guys
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Re: Building my first amplifier. Where to start?
Was discussed some years ago on the amps reflector:
?
?
Its a low ? generator tube with poor iMD and high drive requirements.
?
73
Peter, DJ7WW
?
?
?
-----Original-Nachricht-----
Betreff: Re: [ham-amplifiers] Building my first amplifier. Where to start?
Datum: 2023-12-26T11:55:02+0100
Von: "Jim VE7RF" <jim.thom@...>
An: "[email protected]" <[email protected]>
?
?
?
How do u now the GU5B? only has 10 db of gain ???
?
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Re: Building my first amplifier. Where to start?
Dear Des,
?
Some years ago I invested money into whar was then a seemingly up-and-coming amplifier that used a GU-78b.
?
The first thing I did when setting the amplifier up
was to seek out a spare tube.
?
Some friends of mine in the former Soviet Military
were all too willing to scour the shelves looking for
a spare for me, but alas, there were none apparent.
?
I would say now these ‘78’s are as rare as
Stanley Steamer 3CV1500A7’s, and to steer clear
of building something around one.
?
(In my foolishness my last unfinished QRO project
centered around a pair of GU-84b’s, still in their
Svetlana sealed factory styrofoam cartons.)
?
But even these monsters are getting rarer and rarer.
?
However the ‘35’s are still readily available, and they
make a wonderful combo for easily-driven Cathode
valves.
?
Hal Mandel
W4HBM
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Re: Building my first amplifier. Where to start?
Jim,
I found a reference on the net to someone who has build an amplifier around the GU5b some time agai and he stated gain was low and required 200w drive to maximise output.?
Here is a link to the datasheet if that helps.
What's your thoughts on gu43b's? Also what is the calculation you referenced to approximate input impedance? Thanks,des
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Re: Building my first amplifier. Where to start?
How do u now the GU5B? only has 10 db of gain ???
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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.
Mike
VK2AMF / G3XEF ?
At 07:41 PM 24/12/2023, you wrote:
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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?
Mike Fleetwood
Canberra Australia and Sidcup UK.
Worldwide email address
is:?????
mfleetwood@...
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Re: Building my first amplifier. Where to start?
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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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?
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
|
HaL Mandel
