Re: 144 mhz tuned input for a GG YC-156 ??
I could tell I was beating a dead horse when all the HFers
ignored my earlier comments about plate bypass capacitors made of
two metal plates with an insulating sheet between, and then when
they kept talking about pi-nets while purporting to discuss V/UHF
amplifiers. Some folks seem enamored by the view of lumped
constants arranged and connected willy-nilly. But Hank, W6GGV,
raised me knee-high on stripline design, and I've never forgotten
the difference, nor how easy they are to design (not necessarily
to build, however!). They'll just have to learn the hard way, I
spose, just like I'm having to learn how to make holes in this
desert cliche for tower bases.
I can just imagine one of these characters looking upon a typical
V/UHF amplifier tank circuit and wondering "just HOW the hell can
this thing possibly work?!?! How do you calculate the inductor in
the output tank, fer Gawd's sake???"? 8-)
Steve, K0XP
On 1/6/2024 10:43 AM, Brandon DX via
groups.io wrote:
Steve, K0XP said "Try a 3/4 wavelength stripline. Get the design
info from W6GGV's articles published in the Nov. '80, and Jan.
through April '81 issues of Ham Radio."
Thats right, Steve! a stripline is the way to go. Q is
controllable and thermally there should be little or no drift as
they warm up.? I worked with Bob Sutherland, W6PO, for a year
and he helped me build a chan 13 television test cavity using a
hugemongous 25kW tetrode. The input was a stripline. I am trying
to remember if it was a 3/4 wave line, probably so.
The problem was in the output of the cavity, there wasn't enough
room for a coupling loop. Capacitor coupled outputs allow
harmonic energy to pass on out to the load and a high power
filter would be needed. The project was shelved.?
I knew Russ Miller N7ART (SK) when he was building a 2M PA using
a 3CX1200Z7. The 3CX1500Z7 was introduced about that time and
would be a better tube if one was available (NLA?).? These are
thoriated tungsten triodes with a grid flange, similar to the
YC156 which was introduced before the 1200Z7 was imagined by the
Salt Lake City bunch.
Attached is the N7ART article courtesy of the ARRL, it was in
their handbook of unknown vintage, in the mid 80's.?
Input capacitance of the 1200Z7 is around 17pF, less than a
YC156 but the same principle will work on the larger tube.
Russ used a Pi-L input,? I just looked at the article and
remember him as we spoke often while he was working on the amp.
The benefit of using that tube is 4 second warm-up, not the 3
minutes needed with a YC-156, making it desirable if there was a
sudden E-skip opening or moonbounce, otherwise why use a QRO PA
on 2M for??
I have an unfinished YC156 amplifier that was built by a Italian
ham who was a designer of broadcast transmitters. It wouldn't
work for him at 144MHz. The entire thing is around 4 feet tall.
The output uses transmission line with a copper pipe about the
diameter of the YC156 inside a square enclosure. A copper disc
on a threaded shaft tunes it and it has a copper disc adjustable
closer or further away from the stripline for output coupling.
At the time I could get YC156's that failed some spec for ham
use, they were plentiful while MRI systems were using them but
all that went away when the industry went SS and the ones
showing up on eBay are generally burnt out by CB'ers.
Reid? W6MTF? ??
--
NO on ARRL Bylaw 46!!!
See my QRZ.com page at
|
Re: 144 mhz tuned input for a GG YC-156 ??
Steve, K0XP said "Try a 3/4 wavelength stripline. Get the design info from W6GGV's articles published in the Nov. '80, and Jan. through April '81 issues of Ham Radio."
Thats right, Steve! a stripline is the way to go. Q is controllable and thermally there should be little or no drift as they warm up.? I worked with Bob Sutherland, W6PO, for a year and he helped me build a chan 13 television test cavity using a hugemongous 25kW tetrode. The input was a stripline. I am trying to remember if it was a 3/4 wave line, probably so.
The problem was in the output of the cavity, there wasn't enough room for a coupling loop. Capacitor coupled outputs allow harmonic energy to pass on out to the load and a high power filter would be needed. The project was shelved.?
I knew Russ Miller N7ART (SK) when he was building a 2M PA using a 3CX1200Z7. The 3CX1500Z7 was introduced about that time and would be a better tube if one was available (NLA?).? These are thoriated tungsten triodes with a grid flange, similar to the YC156 which was introduced before the 1200Z7 was imagined by the Salt Lake City bunch.
Attached is the N7ART article courtesy of the ARRL, it was in their handbook of unknown vintage, in the mid 80's.?
Input capacitance of the 1200Z7 is around 17pF, less than a YC156 but the same principle will work on the larger tube.
Russ used a Pi-L input,? I just looked at the article and remember him as we spoke often while he was working on the amp.
The benefit of using that tube is 4 second warm-up, not the 3 minutes needed with a YC-156, making it desirable if there was a sudden E-skip opening or moonbounce, otherwise why use a QRO PA on 2M for??
I have an unfinished YC156 amplifier that was built by a Italian ham who was a designer of broadcast transmitters. It wouldn't work for him at 144MHz. The entire thing is around 4 feet tall. The output uses transmission line with a copper pipe about the diameter of the YC156 inside a square enclosure. A copper disc on a threaded shaft tunes it and it has a copper disc adjustable closer or further away from the stripline for output coupling. At the time I could get YC156's that failed some spec for ham use, they were plentiful while MRI systems were using them but all that went away when the industry went SS and the ones showing up on eBay are generally burnt out by CB'ers.
Reid? W6MTF? ??
|
Re: 144 mhz tuned input for a GG YC-156 ??
If I start from the assumption regarding the input impedance 35 ohms in parallel with 92 pF, this is equivalent to 3.37-j11 in series form. ? If we calculate the 'L' adapter, it gives this ? ? 
? Why would you want to use a pi ? Where is my error ?
|
Re: 144 mhz tuned input for a GG YC-156 ??
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Show quoted text
From: N2LYM [mailto:n2lym@...]
Sent: Friday, January 05, 2024 11:44 PM
To: '[email protected]'
Subject: RE: [ham-amplifiers] 144 mhz tuned input for a GG YC-156 ??? PIEL ? 73 ? N2LYM ? From: [email protected] [mailto:[email protected]] On Behalf Of Robert W5AJ
Sent: Friday, January 05, 2024 11:21 PM
To: [email protected]
Subject: Re: [ham-amplifiers] 144 mhz tuned input for a GG YC-156 ?? ? Jim,?? is there public domain software program that helps with Pi network design? aka,? I'm looking at 8877 50Mhz project in 2024 On Fri, Jan 5, 2024 at 2:28?PM Jim VE7RF <jim.thom@...> wrote: YC-156 is good up to 150 mhz.? ? It will be used on 144 mhz.? ? Yes, the 8877 has a 38.5 pf? between cathode and grid....and is good up to 250 mhz.?? ? Question is.... how the hell do u make a tuned input for 144 mhz, with a whopping 92.5 pf of input C ?? ? With a conventional Pi tuned input....and an overall network Q of '4'? ?( input Q = 2.2)? ( output Q = 1.8)
It's then? C1 = 49.1 pf? ?L= .04 uh? ? C2 =? 56.1 pf? The input C is WAY more than the? required C2 value.? ?Note this is based on a 35 ohm input Z.?
...................................................................................................................................................................................................................................................................................................................................................................................... ? OK, here's what might work....increase the overall network Q to '8'? ? ( input Q =4.4)? ?( output Q = 3.6)? It's then C1 = 96.8 pf? ?L =? .02 uh? ?C2 = 114.4 pf? ? Note, this is based on a 35 ohm input Z.?? trying to fabricate a .02 uh inductor will be a trick. A straight piece of copper strap might just? work.? ? Jim? ?VE7RF
|
Re: 144 mhz tuned input for a GG YC-156 ??
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of Robert W5AJ
Sent: Friday, January 05, 2024 11:21 PM
To: [email protected]
Subject: Re: [ham-amplifiers] 144 mhz tuned input for a GG YC-156 ?? ? Jim,?? is there public domain software program that helps with Pi network design? aka,? I'm looking at 8877 50Mhz project in 2024 On Fri, Jan 5, 2024 at 2:28?PM Jim VE7RF <jim.thom@...> wrote: YC-156 is good up to 150 mhz.? ? It will be used on 144 mhz.? ? Yes, the 8877 has a 38.5 pf? between cathode and grid....and is good up to 250 mhz.?? ? Question is.... how the hell do u make a tuned input for 144 mhz, with a whopping 92.5 pf of input C ?? ? With a conventional Pi tuned input....and an overall network Q of '4'? ?( input Q = 2.2)? ( output Q = 1.8)
It's then? C1 = 49.1 pf? ?L= .04 uh? ? C2 =? 56.1 pf? The input C is WAY more than the? required C2 value.? ?Note this is based on a 35 ohm input Z.?
...................................................................................................................................................................................................................................................................................................................................................................................... ? OK, here's what might work....increase the overall network Q to '8'? ? ( input Q =4.4)? ?( output Q = 3.6)? It's then C1 = 96.8 pf? ?L =? .02 uh? ?C2 = 114.4 pf? ? Note, this is based on a 35 ohm input Z.?? trying to fabricate a .02 uh inductor will be a trick. A straight piece of copper strap might just? work.? ? Jim? ?VE7RF
|
Re: 144 mhz tuned input for a GG YC-156 ??
Jim,?? is there public domain software program that helps with Pi network design?
aka,? I'm looking at 8877 50Mhz project in 2024
73 Robert W5AJ
On Fri, Jan 5, 2024 at 2:28?PM Jim VE7RF < jim.thom@...> wrote: YC-156 is good up to 150 mhz.? ? It will be used on 144 mhz.?
?
Yes, the 8877 has a 38.5 pf? between cathode and grid....and is good up to 250 mhz.??
?
Question is.... how the hell do u make a tuned input for 144 mhz, with a whopping 92.5 pf of input C ??
?
With a conventional Pi tuned input....and an overall network Q of '4'? ?( input Q = 2.2)? ( output Q = 1.8)
It's then? C1 = 49.1 pf? ?L= .04 uh? ? C2 =? 56.1 pf?
The input C is WAY more than the? required C2 value.? ?Note this is based on a 35 ohm input Z.?
......................................................................................................................................................................................................................................................................................................................................................................................
?
OK, here's what might work....increase the overall network Q to '8'? ? ( input Q =4.4)? ?( output Q = 3.6)?
It's then C1 = 96.8 pf? ?L =? .02 uh? ?C2 = 114.4 pf? ? Note, this is based on a 35 ohm input Z.??
trying to fabricate a .02 uh inductor will be a trick. A straight piece of copper strap might just? work.?
?
Jim? ?VE7RF
|
Re: 144 mhz tuned input for a GG YC-156 ??
What does the piece of Heliax do?
On Friday, January 5, 2024 at 05:26:02 PM EST, Peter Voelpel <dj7ww@...> wrote:
A pi-circuit
?
73
Peter, DJ7WW
?
?
?
?
-----Original-Nachricht-----
Betreff: [ham-amplifiers] 144 mhz tuned input for a GG YC-156 ??
Datum: 2024-01-05T20:51:29+0100
Von: "Jim VE7RF" <jim.thom@...>
An: "[email protected]" <[email protected]>
?
?
?
?
?
Ok, how does one go about building a tuned input for a 144 mhz amp, using a YC-156 tube ??
The input C on the YC-156 is huge,? 92.5 pf? ?( grid to cathode).?
This is for a cathode driven? ?YC-156
?
( The 1/2 wave tank for the output side is fine, and tunes up fine, with calculated RL.... to the 50 ohm output.)?
The output is not the issue, it's the input.?
?
What options, if any, do we have ?? ?What's the fix ?
Jim? ?VE7RF
?
|
Re: 144 mhz tuned input for a GG YC-156 ??
Try a 3/4 wavelength stripline. Get the design info from W6GGV's
articles published in the Nov. '80, and Jan. through April '81
issues of Ham Radio.
Steve, K0XP
On 1/5/2024 12:28 PM, Jim VE7RF wrote:
YC-156 is good up to 150 mhz.? ? It will be used on 144 mhz.?
?
Yes, the 8877 has a 38.5 pf? between cathode and grid....and is
good up to 250 mhz.??
?
Question is.... how the hell do u make a tuned input for 144
mhz, with a whopping 92.5 pf of input C ??
?
With a conventional Pi tuned input....and an overall network Q
of '4'? ?( input Q = 2.2)? ( output Q = 1.8)
It's then? C1 = 49.1 pf? ?L= .04 uh? ? C2 =? 56.1 pf?
The input C is WAY more than the? required C2 value.? ?Note
this is based on a 35 ohm input Z.?
......................................................................................................................................................................................................................................................................................................................................................................................
?
OK, here's what might work....increase the overall network Q to
'8'? ? ( input Q =4.4)? ?( output Q = 3.6)?
It's then C1 = 96.8 pf? ?L =? .02 uh? ?C2 = 114.4 pf? ? Note,
this is based on a 35 ohm input Z.??
trying to fabricate a .02 uh inductor will be a trick. A
straight piece of copper strap might just? work.?
?
Jim? ?VE7RF
--
NO on ARRL Bylaw 46!!!
See my QRZ.com page at
|
Re: 144 mhz tuned input for a GG YC-156 ??
A pi-circuit
?
73
Peter, DJ7WW
?
?
?
?
-----Original-Nachricht-----
Betreff: [ham-amplifiers] 144 mhz tuned input for a GG YC-156 ??
Datum: 2024-01-05T20:51:29+0100
Von: "Jim VE7RF" <jim.thom@...>
An: "[email protected]" <[email protected]>
?
?
?
?
?
Ok, how does one go about building a tuned input for a 144 mhz amp, using a YC-156 tube ??
The input C on the YC-156 is huge,? 92.5 pf? ?( grid to cathode).?
This is for a cathode driven? ?YC-156
?
( The 1/2 wave tank for the output side is fine, and tunes up fine, with calculated RL.... to the 50 ohm output.)?
The output is not the issue, it's the input.?
?
What options, if any, do we have ?? ?What's the fix ?
Jim? ?VE7RF
?
|
Re: 144 mhz tuned input for a GG YC-156 ??
Jim, are you building this?
On Friday, January 5, 2024 at 03:28:08 PM EST, Jim VE7RF <jim.thom@...> wrote:
YC-156 is good up to 150 mhz.? ? It will be used on 144 mhz.?
?
Yes, the 8877 has a 38.5 pf? between cathode and grid....and is good up to 250 mhz.??
?
Question is.... how the hell do u make a tuned input for 144 mhz, with a whopping 92.5 pf of input C ??
?
With a conventional Pi tuned input....and an overall network Q of '4'? ?( input Q = 2.2)? ( output Q = 1.8)
It's then? C1 = 49.1 pf? ?L= .04 uh? ? C2 =? 56.1 pf?
The input C is WAY more than the? required C2 value.? ?Note this is based on a 35 ohm input Z.?
......................................................................................................................................................................................................................................................................................................................................................................................
?
OK, here's what might work....increase the overall network Q to '8'? ? ( input Q =4.4)? ?( output Q = 3.6)?
It's then C1 = 96.8 pf? ?L =? .02 uh? ?C2 = 114.4 pf? ? Note, this is based on a 35 ohm input Z.??
trying to fabricate a .02 uh inductor will be a trick. A straight piece of copper strap might just? work.?
?
Jim? ?VE7RF
|
Re: 144 mhz tuned input for a GG YC-156 ??
YC-156 is good up to 150 mhz.? ? It will be used on 144 mhz.?
?
Yes, the 8877 has a 38.5 pf? between cathode and grid....and is good up to 250 mhz.??
?
Question is.... how the hell do u make a tuned input for 144 mhz, with a whopping 92.5 pf of input C ??
?
With a conventional Pi tuned input....and an overall network Q of '4'? ?( input Q = 2.2)? ( output Q = 1.8)
It's then? C1 = 49.1 pf? ?L= .04 uh? ? C2 =? 56.1 pf?
The input C is WAY more than the? required C2 value.? ?Note this is based on a 35 ohm input Z.?
......................................................................................................................................................................................................................................................................................................................................................................................
?
OK, here's what might work....increase the overall network Q to '8'? ? ( input Q =4.4)? ?( output Q = 3.6)?
It's then C1 = 96.8 pf? ?L =? .02 uh? ?C2 = 114.4 pf? ? Note, this is based on a 35 ohm input Z.??
trying to fabricate a .02 uh inductor will be a trick. A straight piece of copper strap might just? work.?
?
Jim? ?VE7RF
|
Re: 144 mhz tuned input for a GG YC-156 ??
Yes, that's 2 1/2 times the value for a 8877 that works good up to 222. Will this tube go that high?
On Friday, January 5, 2024 at 02:51:29 PM EST, Jim VE7RF <jim.thom@...> wrote:
Ok, how does one go about building a tuned input for a 144 mhz amp, using a YC-156 tube ??
The input C on the YC-156 is huge,? 92.5 pf? ?( grid to cathode).?
This is for a cathode driven? ?YC-156
?
( The 1/2 wave tank for the output side is fine, and tunes up fine, with calculated RL.... to the 50 ohm output.)?
The output is not the issue, it's the input.?
?
What options, if any, do we have ?? ?What's the fix ?
Jim? ?VE7RF
|
144 mhz tuned input for a GG YC-156 ??
Ok, how does one go about building a tuned input for a 144 mhz amp, using a YC-156 tube ??
The input C on the YC-156 is huge,? 92.5 pf? ?( grid to cathode).?
This is for a cathode driven? ?YC-156
?
( The 1/2 wave tank for the output side is fine, and tunes up fine, with calculated RL.... to the 50 ohm output.)?
The output is not the issue, it's the input.?
?
What options, if any, do we have ?? ?What's the fix ?
Jim? ?VE7RF
|
KB1SEL got the premade chassis and cabinet from ICA manufacturing in? NJ.? They come completely pre-fabricated and ship flat. All you do is assemble with machine screws. On most of em, they have the outer front panel, and also a 2nd front panel inboard from the outer panel. Stuff like vac caps, verniers etc, is between the 2 x panels.... if you want.?
The pre-made cabinets come in every dimension you can think of.? ?Shipped in the flat pack, the shipping is cheap.? ?ICA runs flat out 6 x days a week.? That's also where the .515" thick teflon chimney for the 10 kw 6m, 3x6 amp came from.?
https://www.icamanufacturing.com/shop/cabinets
ICA Manufacturing
P.O. Box 677
Egg Harbor City, NJ 08215
(609) 965-9494
Chargercharger@...
|
Keep in mind that sometimes, paying somewhat more for the chassis
can make up for a lower shipping cost, too. Compromise,
compromise, compromise...
Steve, K0XP
On 1/4/2024 1:52 PM, mike repinski via
groups.io wrote:
The Amp Repair guy has a few
videos on Utube constructing a few amps. He purchase his
chassis ready made. Check Utube for the name of the supplier.
And yes there are metal suppliers listed on the web. You need
to find a local one to save on shipping.
On Thursday, January 4, 2024 at 04:49:04 PM EST, Tim
Fern <timjfern@...> wrote:
My little local town has Al. supplier who will
guillotine pieces to size for free If the order is over
?10.... I expect most towns will have similar.
I never bend pieces (although my Al. supplier can do
that too for a small charge), I just cut angle-ally
pieces and drill / tap M4 holes.
18 or 20swg for tank circuits, 3mm (10?swg) for
chassis/front panels.
best 73
--
See my QRZ.com page at
|
The Amp Repair guy has a few videos on Utube constructing a few amps. He purchase his chassis ready made. Check Utube for the name of the supplier. And yes there are metal suppliers listed on the web. You need to find a local one to save on shipping.
On Thursday, January 4, 2024 at 04:49:04 PM EST, Tim Fern <timjfern@...> wrote:
My little local town has Al. supplier who will guillotine pieces to size for free If the order is over ?10.... I expect most towns will have similar.
I never bend pieces (although my Al. supplier can do that too for a small charge), I just cut angle-ally pieces and drill / tap M4 holes.
18 or 20swg for tank circuits, 3mm (10?swg) for chassis/front panels.
best 73
|
My little local town has Al. supplier who will guillotine pieces to size for free If the order is over ?10.... I expect most towns will have similar.
I never bend pieces (although my Al. supplier can do that too for a small charge), I just cut angle-ally pieces and drill / tap M4 holes.
18 or 20swg for tank circuits, 3mm (10?swg) for chassis/front panels.
best 73
|
What's good choice for obtaining Aluminum plate, Aluminum Chassis..??
I'm searching ebay, lots of picks.? Others?
Short story, About to cannibalize old amp for chassis but think NEW would turn out better on this one.
I can assemble Aluminum, bend - not so much.
Thickness??
73 Robert W5AJ
|
Re: Gi46b on 2m - Thermal drift problem
It seems fine, I suppose, even above SRF, it's only a few nH.... and is still a DC block ;-)
The Gi46b runs low power as a driver for the final triode so has a pretty easy life.
|
Re: Gi46b on 2m - Thermal drift problem
4x HT50 or 55 do well on 2m with 4CX1000/3CX1500A7 amps.
GI7b and similar tubes drift when cooling is insufficient.
?
73
Peter
?
?
?
-----Original-Nachricht-----
Betreff: Re: [ham-amplifiers] Gi46b on 2m - Thermal drift problem
Datum: 2024-01-04T17:29:29+0100
Von: "Jim VE7RF" <jim.thom@...>
?
?
?
?
?
For the OP, does that plate block cap even look like a cap at? 144 mhz ??? ?Will it handle the calculated rf current flowing through it at 144 mhz ??
John Lyles,? K5PRO helped myself and Scott out on that 10 kw 6m amp.? ?John used his test gear during a 3 way phone conversation, and was testing various HEC / centralab caps, like the 200 pf? and also? 500 pf variety, in both HT-50/58 size, and also HT-57 sizes.? On some of them, the SRF freq (self res freq)? was as low as just 42-45 mhz.? If 3 x caps were in parallel, SRF rose to 62 mhz.? On the HT-57 caps, in 200 pf size, SRF was 60 mhz...and? even higher, when paralleled.?
Above the SRF freq, the cap looks inductive.? ?It's straightforward? test process to find the SRF freq for a given combo of single, or multiple caps in parallel.?
?
|
Brandon DX
Robert, W5AJ