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QuadZilla sees first light - Quad 4X1's - pictures




 
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Author Topic: QuadZilla sees first light - Quad 4X1's - pictures  (Read 33079 times)
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K1JJ
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« on: February 09, 2009, 11:36:32 PM »

Hola,

The new 4-1000A linear amp saw first light tonight. Everything is wired and tested - except for a HV test and RF into the dummy load. I want to do that early in the day... :-)

The filaments, blower, TR, metering and input matching work FB.

As seen in the pics, I built a 'T' network to match 160 - 40M,  50 ohms to 12 ohms. (four tubes in GG parallel equals about 12 ohms input impedance.)

The amplifier has two Plexiglas front panels as well as a 23" X 25" Plexiglas side panel for viewing pleasure.

QuadZilla (As The Derb named it) uses vacuum variables for both the plate tuning and plate loading - with turns counters. It also uses plug-in coils, which I may change to a large rotary band switch later. The amplifier will be used for class A service and driven by four MRF-150 MosFets.

For more info and early pictures, check out the original thread:  http://amfone.net/Amforum/index.php?topic=18568.0

Enjoy the views!

Tom, K1JJ

More pics to come...


* 4X1 Rig 047.jpg (315.16 KB, 1280x960 - viewed 657 times.)

* 4X1 Rig 053.jpg (319.63 KB, 1280x960 - viewed 669 times.)

* 4X1 Rig 043.jpg (328.92 KB, 1280x960 - viewed 745 times.)
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Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
K1JJ
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« Reply #1 on: February 09, 2009, 11:38:31 PM »

More Pics:

Notice the adjustable 50 ohm to 12 ohm T network with roller inductor.

That filament transformer is feeding 7.5V at 84 amps.

Both the fil xfmr and blower are on 240V variacs for full range adjustments.

This is one of the few rigs I've built were there's plenty of room left over to work on it... :-)


* 4X1 Rig 034.jpg (306.75 KB, 960x1280 - viewed 656 times.)

* 4X1 Rig 033.jpg (330.22 KB, 1280x960 - viewed 615 times.)

* 4X1 Rig 032.jpg (314.99 KB, 1280x960 - viewed 606 times.)
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Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed. 

Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
K1JJ
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« Reply #2 on: February 09, 2009, 11:40:06 PM »

More QuadZilla under Plexiglas:

I tried real hard to keep the plate RF strapping as short as possible. It was difficult with an in-line layout. However, I think it worked out FB.  The only thing to do now is to FIRE IT UP into a dummy load to find out.


* 4X1 Rig 029.jpg (319.33 KB, 1280x960 - viewed 537 times.)

* 4X1 Rig 027.jpg (322.79 KB, 1280x960 - viewed 640 times.)

* 4X1 Rig 038.jpg (322.18 KB, 1280x960 - viewed 619 times.)
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Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed. 

Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
K1JJ
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« Reply #3 on: February 09, 2009, 11:41:03 PM »

Early construction pics:


* 4X1 Rig 011.jpg (322.18 KB, 1280x960 - viewed 679 times.)

* 4X1 Rig 022.jpg (317.99 KB, 1280x960 - viewed 552 times.)
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Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
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« Reply #4 on: February 10, 2009, 06:36:26 AM »

Shielding?  SHIELDING?  We don't need no Stinkin' shielding   Wink
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WB2YGF
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« Reply #5 on: February 10, 2009, 07:41:39 AM »

Shielding?  SHIELDING?  We don't need no Stinkin' shielding   Wink

Good thing Hams don't need FCC type acceptance for homebrew.  Grin
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Steve - WB3HUZ
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« Reply #6 on: February 10, 2009, 08:49:09 AM »

Why would shielding be needed?
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KL7OF
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« Reply #7 on: February 10, 2009, 09:31:09 AM »

Excellent Tom....!!
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ab3al
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« Reply #8 on: February 10, 2009, 10:13:41 AM »

does it do 11 meters?
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Fred k2dx
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« Reply #9 on: February 10, 2009, 10:36:56 AM »

Shielding? Cable TV is shielded! Might be good to check the outpoot circuit for VHF resonances?

My single 4x1 produced an awesome event of releasing energy when the plate parasitic suppresor (5 parallel 2 watt resistors inside the small coil) eventually cooked... replaced with nichrome and a globar... now that suppresor could supress the VHF energy running at 6kv B+. 
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« Reply #10 on: February 10, 2009, 10:55:36 AM »

kl7of,
Maybe a battle brewing here.  MODZILLA (aka Pauli Guhrl) vs quadzilla coast to coast Saturday night brawl.
woc
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Bob (aka Boatyard)
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« Reply #11 on: February 10, 2009, 11:50:44 AM »

When you're in an old buzzard qso some night and you feel unusually warm you may rethink the shielding situation.
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K1JJ
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« Reply #12 on: February 10, 2009, 11:56:56 AM »

heheheheh...

Yep, I had hoped we'd get a rise outa this project!

Today we'll attempt firing up "QuadZirra" into the dummy load. (the Japanese pronunciation)   I'll probably use the 3kv supply and later stick 6kv to her and watch her scream like a stuck dinosaur.


Shielding?  I could always add some of that fine metal screening to the Plexiglas. I just may do that. Though, my other rigs under Plexi haven't caused any RF in the audio or similar problems.  When someone axes about BA radiation, I always refer to the group of OT's from the 20' and 30's who died around the same time, back about 15 years ago.  It was listed in the AWA periodical.... these guys were the pioneers of radio, working around 10's of KW with no shielding for years. Most lived into their mid to late 90's. If anything, it'll clean out the stray crabs... :-)

I'm a little concerned about the vhf parasitic suppressor resistors. I'm using nichrome wire for each tube, but the resistors are only 2 watts. I only have two 50 ohm glow bars, so need more. If there are no parasitics, then the resistors will be OK. Being GG and operating no higher than 7mhz, it'll probably be pretty stable, but ya never know til ya smell that smell.

Unlike the rest of the house, my shack is a little colder cuz there is no cellar below it. Quadzirra will help a lot until it warms up.

Updates to come.

T
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Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed. 

Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
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« Reply #13 on: February 10, 2009, 11:57:33 AM »

Cool rig Tom!!  Now lets see.....if I can ever get going again on it....a pair of 6C21s modulated by a pair of 304TLs should make a little noise.  I believe I will call it Kahoona III.  (Kahoona II is a 4CX1000/4CX1500B leenyar).

73,  Jack, W9GT
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« Reply #14 on: February 10, 2009, 02:41:51 PM »

DAM you're fast Tom,
From birth, just a chassis with tubes and a PC board, to a working ANIMAL.
You will have to give encoded text for the Bird Watts out with the 6KV supply.

Are you planning any harmonics in your future. This thing may be the final step toward sterilzation.

Fred
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Fred KC4MOP
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« Reply #15 on: February 10, 2009, 04:04:09 PM »

Tom,

you should cop some nichrome ribbon offa ebay. unless that wires big you're gonna se it go poof when you apply the coals to it. put some  heavy nichrome STRAP on them bad boyz....
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Steve - WB3HUZ
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« Reply #16 on: February 10, 2009, 04:19:39 PM »

HF is non-ionizing radiation. Take a look at the MPE limits. Even at a few feet, there is not enough radiation coming off the short leads in that transmitter to be anywhere near the limits. You'll do more damage using a cell phone than operating that transmitter.


heheheheh...

Yep, I had hoped we'd get a rise outa this project!

Today we'll attempt firing up "QuadZirra" into the dummy load. (the Japanese pronunciation)   I'll probably use the 3kv supply and later stick 6kv to her and watch her scream like a stuck dinosaur.


Shielding?  I could always add some of that fine metal screening to the Plexiglas. I just may do that. Though, my other rigs under Plexi haven't caused any RF in the audio or similar problems.  When someone axes about BA radiation, I always refer to the group of OT's from the 20' and 30's who died around the same time, back about 15 years ago.  It was listed in the AWA periodical.... these guys were the pioneers of radio, working around 10's of KW with no shielding for years. Most lived into their mid to late 90's. If anything, it'll clean out the stray crabs... :-)

I'm a little concerned about the vhf parasitic suppressor resistors. I'm using nichrome wire for each tube, but the resistors are only 2 watts. I only have two 50 ohm glow bars, so need more. If there are no parasitics, then the resistors will be OK. Being GG and operating no higher than 7mhz, it'll probably be pretty stable, but ya never know til ya smell that smell.

Unlike the rest of the house, my shack is a little colder cuz there is no cellar below it. Quadzirra will help a lot until it warms up.

Updates to come.

T
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K1JJ
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« Reply #17 on: February 10, 2009, 04:22:44 PM »

Just finished the first sea trials with QuadZirra on 75M, into a dummy load.  I started slowly cuz of fear -  hooked up the smaller 3500V supply. Drove her with 20 watts of AM carrier from the FT-102 directly.

Plate current idle looks good. I swung the plate and input tuning caps all different ways and could see no instability.

I added the limited drive, tuned her up and she puked out about 2200 easy watts. (Bird watts into a 50 ohm Bird dummy load, caw mawn)
Pattern loooks clean on the scope, no signs of parasitics or oscillations of any kind.  The AM positive audio peaks flew off the screen - that's a good thang.

The input T network adjusted the 50 ohms from the FT-102 to the 12 ohms tube input to 1:1 - easy.

I see a problem with the third tube towards the rear. It shows much less color than the other three. Probably slightly soft. Gotta locate another tube. They're all pulls anyway.

Might hook up the big HV supply and then drive her with the MRF-150's MOSFET amp within a day or so.

Added some diodes in the fil CT for bias. At 3500V she idles at about 250 ma with NO diode bias in there. At higher plate voltage she will need some bias to idle down.

I'm pleased with the amplifier gain. As far as I can tell, it's about 13db, which is in line with what someone said in a recent thread for GG 4X1's. I'll make some more accurate measurements later.

All tube plate color pics are taken when putting out a 2200W carrier. (pep) This is about 30% efficiency (like class A) but would increase to about 65% with higher drive in class B.  I noticed with higher drive, the plate color stays the same while the power output goes up, as expected.

When compared against the total AC power taken from the mains with my plate modulated 4X1 X 833A's, it's really not a bad deal overall.

T


* 4X1 Rig 056.jpg (331.92 KB, 1280x960 - viewed 757 times.)

* 4X1 Rig 057.jpg (347.5 KB, 1280x960 - viewed 654 times.)

* 4X1 Rig 061.jpg (324.31 KB, 1280x960 - viewed 870 times.)
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Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed. 

Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
K1JJ
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« Reply #18 on: February 10, 2009, 04:24:24 PM »

Mo pics:

Scope Yallo.


* 4X1 Rig 062.jpg (321.01 KB, 1280x960 - viewed 578 times.)

* 4X1 Rig 054.jpg (328.56 KB, 1280x960 - viewed 541 times.)
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Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed. 

Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
Steve - WB3HUZ
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« Reply #19 on: February 10, 2009, 04:26:35 PM »

Awesome! Looks cool, sounds good. You got it all.
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KL7OF
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« Reply #20 on: February 10, 2009, 05:11:59 PM »

In the bird watts pic.....what is that smaller meter in the background measuring?  The ft 102? 
In the scope Yallo pic.....Is that the carrier pinching down to the baseline?  Hard to see any positive peaks   are you using a slow sweep? 
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K1JJ
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« Reply #21 on: February 10, 2009, 06:05:15 PM »

In the bird watts pic.....what is that smaller meter in the background measuring?  The ft 102? 
In the scope Yallo pic.....Is that the carrier pinching down to the baseline?  Hard to see any positive peaks   are you using a slow sweep? 

In my best Japanese accent, "Oh, you vely smalt man!"

Yes, the little Midland swr meter is drive from the FT-102 where I can adjust it for min swr into the 4X1's.  Right now it is uncalibrated and overdriven. Normally there is no reflected.

The scope is showing a low bass note and is expanded.  If I do a whistle, I can see 200%++ peaks, since it's a balanced modulator driving the amp.  Maybe I'll take a better scope shot of it using an audio tone and post later.

All tube plate color pics are taken when putting out a 2200W carrier. (pep) This is about 30% efficiency (like class A) but would increase to about 65% with higher drive in class B.  I noticed with higher drive, the plate color stays the same while the power output goes up, as expected.

In class B, when compared against the total AC power taken from the mains with my plate modulated 4X1 X 833A's, it's really not a bad deal overall. I'm really pleased with results so far.

If you get on this weekend, maybe we can make a first contact using QuadZirra and your Fred Flintsone rig, Steve.... :-)

T

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Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
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« Reply #22 on: February 10, 2009, 07:04:12 PM »

I think you need more blower...
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« Reply #23 on: February 10, 2009, 07:24:58 PM »

Can you 'splain "carrier. (pep)"?

Is that 2200W carrier with the ability to do 100% maululation on top of it
or
Is 2200W the PEP level under the present conditions, and you are testing it with a 2200W CW signal?

danke
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K1JJ
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« Reply #24 on: February 10, 2009, 08:08:34 PM »

I think you need more blower...

Hola Frank-

Are you basing that on the tube's plate color or size of the blower?

I think you're right and it's easily curable.

I have a 240 Variac on the blower now and it's set to a low speed at 120V. I can easily increase it to a hurricane at 240V, but the air noise comes up too. Once I settle in on a power and voltage level, I'll adjust the air accordingly. It might mean not running as much audio compression as I usually like to do.

Also, remember that the amp is running close to class A at 30% eff with little drive.  If I drive it harder, the power out goes way up and the color stays pretty constant, probably approaching 65% eff.




Danke said:

"Can you 'splain "carrier. (pep)"?
Is that 2200W carrier with the ability to do 100% maululation on top of it

or Is 2200W the PEP level under the present conditions, and you are testing it with a 2200W CW signal?"

Hi Danke,

The latter is correct.

Just to clarify further, if you drive an amplifier to near saturation with a dead carrier, you can consider this the maximum power it will put out. This is also the peak envelope power "pep" of the amplifier. So, when running AM, we would decrease our carrier by 1/5 or so to give room for our voice peaks and asymetrical voices -  and let our audio peaks reach near the pep level.

When I mentioned carrier/ pep, it was shorthand for saying I didn't have any more drive available for the test, so that the max power I cud get out of the amp was 2200W full dead carrier which is also pep for that drive level. If I were to switch to AM, my AM carrier wud be about 450w with 2200w peak audio power out.

I later tried the amp with move drive and found it was capable of much more pep output with the same plate color (dissipation) using 3.5 KV.



T
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Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed. 

Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
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