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No but I have the WD7S version, complete with all parts and instructions. No idea what it is worth.

See

Also, for a picture of a completed board, see

73, Alek VK6APK

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In Europe Capton or Mica were used as insulation material on broadcast amplifier tubes and capacitors by companies like Plisch, R&S, Siemens, SEL etc..

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I used Teflon with my YL1056 to insulate the tube from the copper tubing of the coaxial output circuit.

I built that amp in 1988 and never had any problem with the insulation.

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73

Peter DJ7WW

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Betreff: Re: [ham-amplifiers] 144 mhz tuned input for a GG YC-156 ??

Datum: 2024-01-07T18:53:19+0100

Von: "Jim VE7RF" <jim.thom@...>

An: "[email protected]" <[email protected]>

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Yes, it is a 2m amp with YC-179.

The quarter wave stub is a notchfilter for harmonic supression.

The amplifier is built and used by a friend.

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73

Peter

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-----Original-Nachricht-----

Betreff: Re: [ham-amplifiers] 144 mhz tuned input for a GG YC-156 ??

Datum: 2024-01-07T17:52:04+0100

Von: "Jim VE7RF" <jim.thom@...>

An: "[email protected]" <[email protected]>

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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

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Guess what the #1 component that fails in FM broadcast is ?? ?It's always the teflon plate block assy.? ?I just saw one, this time made from polyimide? cut loose 6 months ago, ruptured, blew up.?

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Years ago, I tried a hb plate blocker by 1st wrapping the entire circumference of the anode with teflon sheeting....then a wrap of wide copper strap ( narrower than the teflon sheet).? ?Problem is.... the total C is formed by the entire circumference,
but the rf current exits the blocker at only one point.... so it's all concentrated at one point of the circumference.? ?You can also get imperfections (air pockets) between the anode and teflon...and also between teflon and copper strap.? That's when the corona starts up..... and you can't see it.? I experimented with it, using a YC-243 tube, with it's 6.125" OD anode cooler / 19.24" circumference? ( socketless 3x6)? for 2 months...then gave up, went back to a conventional assy, using paralleled? HT-57's.?

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In the older arrl books, and also orr books, they both depict 8877 being used on 144 mhz...and also 220 mhz..... and both used a T network for the tuned input.?

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Years ago? I had buddy try a T network? ( series coil, shunt C, series coil)? ?on his 2 x GS35B? 6m amp.? ?After a week, gave up, went to a pi net, with small air caps and one coil.... end of problem.?

If a simple T / PI network will work as a tuned input......mounted right at the cathode.....and is fully adjustable, what is the advantage of a strip line config ???

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My issue with any tuned input is...... change anything, like drive level, bias, B+, length of coax to xcvr (or ipa), etc, and it always has to be re-tweaked a bit.? That's why a fixed tuned input was not used on the 3x6? 6m amp.? Besides, we needed something? we can slam 500-700 watts? CCS? drive level......on data modes.?

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On these multiband? GG triodes,? I was not about to construct 5-9 separate PI tuned inputs...all bandswitched.? 2 x broadcast caps ( padded on 160m) and a simple 4 uh tapped tubing coil works superb.? We tested it on every band by stuffing a 800 w cxr though it on each band for 10 mins...then into the 2nd bird meter, then the 50 ohm DL.? ?6:1 verniers on both caps..then the 0-100 scale.? Then it's just...'tune by the numbers'.?

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On my next amp, I'm going to 1st experiment with a new 0 - 4.4? uh roller coil ( multronics / cardwell...now called Viking).? It's wound with 8 ga wire. Then I can experiment with changing the Q on any band..... the idea is to see the effects of IMD? vs tuned input Q, and other parameters.?

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Jim? VE7RF

Jim,?? is there public domain software program that helps with Pi network design?

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aka,? I'm looking at 8877 50Mhz project in 2024

73 Robert W5AJ

Don't mess with the PIEL software.? The gold standard is the GM3SEK? PI / PI-L spreadsheet.? ?It's better since it factors in everything, like stray C....and also the all important stray L? Any stray L (intentional or otherwise) between the anode and the C1 tune cap? will form a step down L network....which will reduce the plate load Z to a lower value.? This L network uses the tube's? anode to? grid C + the extra fractional? uh before the C1 tune cap.?

The GM3SEK software also factors in the parasitic suppressor if one is used.? ?It also factors in the plate choke.?

I use the GM3SEK software for all amps? from 160-6m.?

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I also use it for PI tuned inputs.... but there is a trick to this.? The software won't match 2 x identical Z's...so the 'workaround'? is to alter one a tiny bit.? IE: 50 ohms to 49.999 ohms..... presto, works superb. In the case of the tuned input, everything else is zeroed out....( except for the plate choke....enter '9999 uh'? for the plate choke). .? Where the plate load Z normally gets entered, you enter 50 ohms..... then enter 49.999 ohms for the load end.

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You can also tweak the total network Q.? ?Total network Q = sum of the input and output Q.? Both Eimac and older ARRL books only used the input Q.? Typ with an amplifier, with a total network Q of? '12'.? The input Q = 10..and the output Q? ='2'.

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On tuned inputs, where both? ends are 50 ohms,? typ a total network Q of '4' is used....with the input Q = '2'..and the output Q = 2.

On the high power output tank, (160-6m)? in most cases, the extra coil has to be installed between the plate block cap assy...and the C1 tune cap...forming a step down L network. The plate load Z is stepped down to a much lower value, low enough that a practical? PI network can be built, using a much lower Q.... on the highest band? on a multiband amp.? ?Ditto with any mono band? 12/10/6m amp.? ?With out the extra fractional uh installed, the resulting loaded Q is sky high, due to the tube's anode to grid C? (which rises a bunch when tube plugged into the grid ring..... or grid flange bolted to the chassis).? ?The extra C comes from the proximity of the lower anode fins to the chassis below it.? The u can also get even more stray C between anode to rear / side walls....if tube too close.? ?All that stray C is easily measured.? ? WE call that network a L-PI? since it has the extra uh.? ?An? L-PI-L also works.? I stay away from PI-L networks since plenty of harmonic attenuation is obtained with the simple PI (or L-PI) setup.?

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On the 6M? ?3CX-6000A7 amplifier, the extra fractional uh was obtained using a 1" wide cu strap in a semi circle, forming an arc.? ?Main inductance between the vac tune and vac load caps was done the same way....and both? straps are at right angles.? Eff is sky high across the entire 6m band, 72.5%...... and an easy 10 kw CCS? brick on key. By forming the strap into a semi circle, the strap will conduct current on both sides. Input swr is dead flat from 50-54 mhz...since it uses a manually tuned, PI tuned input.? ? Again, it ample harmonic suppression.? If more is required, a simple shorted 1/4 wave stub can be added, BUT it has to be inserted exactly an electrical 1/4 wave length downstream from the C2 load cap.? In the case of the 3x6 6m amp, the vac load cap is mounted to the inner front panel, then into the paralleled RJ2B's..... then a long length of SFT-600? to the rear panel 7-16 DIN connector.?

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The only time u can insert the shorted 1/4 wave stub directly on the output of an amp, is if it's PI-L config. ( or a L-PI-L).?

A pi-circuit

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73

Peter, DJ7WW

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##? I don't get it.? You already depict a PI network, with adjustable pair of caps and small coil.? ?How exactly does the heliax fit into the overall scheme ?? ?Is this? 144 mhz amp with the YC-156 ???

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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

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? ??

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? ??

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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

YC-156 is good up to 150 mhz.? ? It will be used on 144 mhz.?

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Yes, the 8877 has a 38.5 pf? between cathode and grid....and is good up to 250 mhz.??

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Question is.... how the hell do u make a tuned input for 144 mhz, with a whopping 92.5 pf of input C ??

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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.?

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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.?

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Jim? ?VE7RF

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A pi-circuit

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73

Peter, DJ7WW

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-----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]>

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