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Recommend AM linear




 
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W1AEX
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« Reply #25 on: April 04, 2009, 12:25:24 PM »

Assuming you're going to be driving this with your Flex 5000A, it is just a matter of how much carrier power you are looking for and how much money you want to spend.  (I'm assuming here that you don't want to volunteer for cafeteria duty again to fund this...)

I am another Ameritron AL-80B user (single 3-500ZG) and it handles up to 200 watts of carrier output during AM operation without any sweat. Typically, I run it at around 150 watts of AM carrier and it swings up to 500-600 watts PEP without complaining. I have run it at 500 watts (output) with RTTY and it has no issues with that either. The specs say it will do a kilowatt of SSB but I never push it that hard and typically see 750 - 800 watts PEP output. The simplicity of running a single big transmitting tube rather than multiple 811's or 572's was a determining factor for me when I picked up my amp. The AL80B has a very rugged power supply and one nice big transmitting tube in an easy to handle package. Another nice feature is that 160 meters is covered as well as the standard 80-10. The driving power to output power ratio is about 1:10 so 15 watts of AM drive produces roughly 150 watts of AM output. I believe it is the best bang for the buck at this time.

One other thing to consider is whether or not you are going to be feeding your new amplifier with a 240 volt line. If you are going to be running it from a 120 volt outlet, that seriously limits your choices.

73,

Rob W1AEX
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One thing I'm certain of is that there is too much certainty in the world.
KA1ZGC
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« Reply #26 on: April 04, 2009, 12:31:33 PM »

Wouldn't carrier be 750 watts if PEP limit is 1500 watts, with 100% modulation, pos peak is 1500, neg peak 0W?

No.

At 100% modulation, PEP = carrier power * 4, not 2.

Just like doubling your AC voltage cuts your I2R losses to 1/4.
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KM1H
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« Reply #27 on: April 04, 2009, 01:24:31 PM »

Amp Supply has been gone for almost 20 years but they sold a lot of amps. The LK-800 will do the job 24/7 but even now they bring big pesos.

The Ameritron AL-1200 and AL-1500 will also rumble along and both are in production. The AL-82 is a few watts down in dissipation but also good.

Various models of the Ten Tec Titan, Dentron DTR-2000L (needs mods for reliability), B&W or Viewstar PT2500/2500A also come to mind.

In some cases you may want to either drop power down a bit or use an external fan to provide a bit of air on the xfmr.

Carl
KM1H
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Burt
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« Reply #28 on: April 04, 2009, 04:14:10 PM »

For AM, instaneous plate voltage doubles at 100% mod.. Thus
PEP is four times carrier.

Pete

I thought I knew something. After all I was chief engineer at two small stations, one a 1KW AM with 13KW FM. Clearly I am way below many of you as the responses seem to have come from geniuses. Let me clarify. I would like a tube amp that would loaf at 200 watts AM. I cannot build or modify (unless it is an old broadcast transmitter). I can fix as long as I have a schematic. I am not going to buy an Alpha. They are overpriced.
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Burt
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« Reply #29 on: April 04, 2009, 04:16:16 PM »


And for the same money, you can find an SB220...  2 500Zs, a slightly bigger power supply, and it doesn't weigh much more.

Its only good for about 200 to 300 watts AM carrier, though :/


--Shane




I had an SB220 years ago, not going there again
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Burt
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« Reply #30 on: April 04, 2009, 04:17:19 PM »

What are you going to be driving it with? How about a plate modulated amp?
N8QPC

I have to drive it?
No I am not that stupid.
A Flex 5000A
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Burt
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« Reply #31 on: April 04, 2009, 04:20:19 PM »

I do not have 220V. I thought if you had a 100w carrier, 100w of plate modulation modulates it 100% for 200W pos peak, 0 neg peak



Assuming you're going to be driving this with your Flex 5000A, it is just a matter of how much carrier power you are looking for and how much money you want to spend.  (I'm assuming here that you don't want to volunteer for cafeteria duty again to fund this...)

I am another Ameritron AL-80B user (single 3-500ZG) and it handles up to 200 watts of carrier output during AM operation without any sweat. Typically, I run it at around 150 watts of AM carrier and it swings up to 500-600 watts PEP without complaining. I have run it at 500 watts (output) with RTTY and it has no issues with that either. The specs say it will do a kilowatt of SSB but I never push it that hard and typically see 750 - 800 watts PEP output. The simplicity of running a single big transmitting tube rather than multiple 811's or 572's was a determining factor for me when I picked up my amp. The AL80B has a very rugged power supply and one nice big transmitting tube in an easy to handle package. Another nice feature is that 160 meters is covered as well as the standard 80-10. The driving power to output power ratio is about 1:10 so 15 watts of AM drive produces roughly 150 watts of AM output. I believe it is the best bang for the buck at this time.

One other thing to consider is whether or not you are going to be feeding your new amplifier with a 240 volt line. If you are going to be running it from a 120 volt outlet, that seriously limits your choices.

73,

Rob W1AEX
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ka3zlr
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« Reply #32 on: April 04, 2009, 04:57:32 PM »

..ain't saying a word anymore.....Excuse Us...
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Detroit47
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N8QPC on your AM dial


« Reply #33 on: April 04, 2009, 05:10:15 PM »

I didn't realize I was dealing with a genius. If you are a broadcast engineer I am surprised you donít build your own. But who am I to question greatness.
73 N8QPC
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KA1ZGC
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« Reply #34 on: April 04, 2009, 05:53:31 PM »

I thought I knew something. After all I was chief engineer at two small stations, one a 1KW AM with 13KW FM. Clearly I am way below many of you as the responses seem to have come from geniuses.

That attitude will get you nowhere. It was you who asked us for guidance, not the other way around.

We are trying to answer your questions. You'll find there are quite a few BC engineers (current and former) on this board, several of whom are participating in this thread and trying to give you the help you're asking for.

As a BC engineer, you never needed to know that your 1kW AM's PEP output was 4kW instead of 2kW. AM broadcast stations are licensed to a specific carrier power level, not PEP. The fact that you were once a chief engineer somewhere doesn't make your assumptions any more accurate, or impress any of us.

PEP @ 100% modulation = unmodulated carrier power * 4. That's a fact, whether you choose to accept it or not.

Now that you've revised your criteria to 200W, the answer is much more simple: pretty much any amplifier on the market can do that. You've found a reason to scoff at just about every linear suggested, so at this point I'd say you're on your own, pal. Just pick one and run it.

One last piece of advice: next time you ask for help, try to avoid getting all indignant because people are trying to help you.

Toodles.

--Thom
Kilowatt Amplifier One Zero Grid Current
p.s. You're welcome.
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Ralph W3GL
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« Reply #35 on: April 04, 2009, 07:05:13 PM »

     




     Geez, shades of Johnie, W3EGC who is still in the cucunest...

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73,  Ralph  W3GL 

"Just because the microphone in front of you amplifies your voice around the world is no reason to think we have any more wisdom than we had when our voices could reach from one end of the bar to the other"     Ed Morrow
Burt
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« Reply #36 on: April 04, 2009, 08:10:43 PM »

I didn't realize I was dealing with a genius. If you are a broadcast engineer I am surprised you donít build your own. But who am I to question greatness.
73 N8QPC

I am NOT the genius, the respondents are
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Burt
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« Reply #37 on: April 04, 2009, 08:17:18 PM »

Whoa, whoa. I appreciate the help. I was not being sarcastic, most of you are far smarter than I, FAR smarter. I highly respect the answers. They have been VERY educational. How is it that you and others misinterpeted what I meant? I lean to the AL-80 AS RECOMMENDED. The reason I came to this forum is I suspected I would get help, but the respondents EXCEEDED my expectations


I thought I knew something. After all I was chief engineer at two small stations, one a 1KW AM with 13KW FM. Clearly I am way below many of you as the responses seem to have come from geniuses.

That attitude will get you nowhere. It was you who asked us for guidance, not the other way around.

We are trying to answer your questions. You'll find there are quite a few BC engineers (current and former) on this board, several of whom are participating in this thread and trying to give you the help you're asking for.

As a BC engineer, you never needed to know that your 1kW AM's PEP output was 4kW instead of 2kW. AM broadcast stations are licensed to a specific carrier power level, not PEP. The fact that you were once a chief engineer somewhere doesn't make your assumptions any more accurate, or impress any of us.

PEP @ 100% modulation = unmodulated carrier power * 4. That's a fact, whether you choose to accept it or not.

Now that you've revised your criteria to 200W, the answer is much more simple: pretty much any amplifier on the market can do that. You've found a reason to scoff at just about every linear suggested, so at this point I'd say you're on your own, pal. Just pick one and run it.

One last piece of advice: next time you ask for help, try to avoid getting all indignant because people are trying to help you.

Toodles.

--Thom
Kilowatt Amplifier One Zero Grid Current
p.s. You're welcome.
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KX5JT
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« Reply #38 on: April 04, 2009, 08:40:46 PM »

Whoa, whoa. I appreciate the help. I was not being sarcastic, most of you are far smarter than I, FAR smarter. I highly respect the answers. They have been VERY educational.

The written word is far inferior to spoken language and without the inflections, intonations, emphasis and de-emphasis it can be grossly misunderstood.  Nevertheless, I understood your humble attitude as just such probably because I feel humbled by the vast knowledge here as well.  I certainly and thoughoughly enjoy this thread and others that are so very educational.  I made a simple suggestion on an old Heathkit Warrior amplifier that claimed to be able to do 400 watts AM carrier (which I believe to be somewhere in the area of legal limit) more to find out what others thought about it too.  It certainly comes from the era before all the limitations were imposed upon amp makers because of the 11 meter chaos.  Its price seemed reasonable too.  Of course now that I know you are wanting to match it up with a Flex-5000 I understand your need for complete coverage of all the bands and maybe the money isn't that much of an issue.  (One day I hope that to be my case!)

At anyrate, I always enjoy your videos Burt and whenever you do obtain whichever amplifier you choose, I look forward to another youtube video highlighting the Flex-5000 with it on AM.

 Cool  This is Kay Ecks Five Jay Tee
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AMI#1684
N3DRB The Derb
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« Reply #39 on: April 04, 2009, 10:08:57 PM »

warrior cant do 400 watt carrier - maybe 175 with 572's. But it's a good low cost am amp. Unless you're dealing with modern crap like hypersil transformers, weight = scrotefulness.  I would not mind getting one myself

the Commanche would be pretty killin on am with more cooling i would think, but I dont know much about them. almost made of unobtainium.

The one I did see was MASSIVE in both size and weight. some fester many many years ago. I do remember thinking how scroteless a SB 220 looked compared to it.


http://www.heathkit-museum.com/ham/hvmkl-1.shtml



* kl-1.jpg (13.31 KB, 340x235 - viewed 485 times.)

* ks-1.jpg (18.87 KB, 340x328 - viewed 472 times.)
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Jim, W5JO
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« Reply #40 on: April 04, 2009, 10:31:57 PM »

warrior cant do 400 watt carrier - maybe 175 with 572's. But it's a good low cost am amp. Unless you're dealing with modern crap like hypersil transformers, weight = scrotefulness.  I would not mind getting one myself


One would have to know the person that placed the ad to understand its meaning Derb.
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N3DRB The Derb
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« Reply #41 on: April 04, 2009, 10:36:30 PM »

yeh. true. I would not make good ad writer using words like " THE DERB 1000" - On AM IT'S SCROTEFUL!!!!!!!!!

they'd be like, WTF??!!!!  Huh Tongue


it occurs to me I have not a clue what you meant Jim. Excuse me, I've been rather rough as of late.  Tongue

----and I'm tripping on my 10 pm pills at the moment, which also does not help.  Embarrassed
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WQ9E
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« Reply #42 on: April 04, 2009, 10:45:58 PM »

Derb,

I have a Chippewa (KL-1) and it does make the SB-220 look pretty wimpy by comparison.  I have run mine at 300 watts carrier on AM and it does that with no problem and could probably do a bit more but it would be pushing the finals pretty hard.  The only major problem with the Chippewa is having the plate current meter sitting at full plate voltage above ground.  I can easily imagine drawing an arc from the pointer to your finger (and no, I don't touch this meter while power is applied).  It also has a noisy blower but it does provide plenty of cooling to keep the 4-400's happy. 

Mine came with a homebrew version of the power supply which tips the scales at just over 140 pounds.  The original owner's son-in-law was the body shop manager at a Lexus dealership and he had the HP instrument case which contains the power supply painted and baked to exactly match the amp itself. 

Rodger WQ9E
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Rodger WQ9E
N3DRB The Derb
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« Reply #43 on: April 04, 2009, 10:52:28 PM »

you mean the pointer set screw is at full B+ or the whole meter? I believe I'd be putting some lexan over that zero set.  Grin
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WQ9E
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« Reply #44 on: April 04, 2009, 11:08:18 PM »

Well,
The set screw is theoretically insulated but again I keep my distance from it.  I seldom use this amp when visitors are in the shack just to make sure someone doesn't get fried. 

My Hallicrafters HT-19 (NBFM and CW rig) brings the plate (~1,800 volt) and screen supplies out to pairs of binding posts on the rear panel (for hookup to an external modulator).  When I got it these had no protective cover and no indication of how a cover could be installed so I made a Plexiglas cover for it.  The cosmetically matched SX-42 receiver has a cover to avoid shocks from the high impedance audio output.  I guess the assumption was the SX-42 was a consumer product but only hams would buy the HT-19 and should know not to touch the binding posts.  I don't believe the HT-19 went into full production as the manual sheets I got with it were stamped PRELIMINARY and every manual copy I have seen for it has the same stamp.  Mine came from a silent key estate-it might have been the root cause for the estate sale.

Rodger WQ9E
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Rodger WQ9E
N3DRB The Derb
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« Reply #45 on: April 05, 2009, 05:34:13 AM »

Quote
I don't believe the HT-19 went into full production

well, yeah. It killed everyone that bought one. Sure way to hold down those sales. whutta deathtrap. Roll Eyes
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W3RSW
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Rick & "Roosevelt"


« Reply #46 on: April 05, 2009, 08:27:35 AM »

Finally got around to reading this thread.  Been way too busy trashin' and addin' to others.  Grin

Derb, Roger,  that Chippewa is one neat beast!  The Indian series has to be the all time greatest design. The Chippewa is the pinnacle. Rates right up there with Art Deco stuff in the '20's as far as looks.  Chromed knobs and all that stuff is way to costly for commercial rigs these days.

Roger, really nice P.Supply painted to match. Derb, I'm Curious, what did the original supply use to regulate the screen voltage on the 4-100's in linear service, a string of VR tubes?
If so, I guess they're hidden under the covers in the pix you sent.  Rog, VR tubes in yours?

Ralphie, every time I see your icon pix, I get a chuckle.  Were that I so kuhl as a JN, heh, heh.
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RICK  *W3RSW*
ab3al
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« Reply #47 on: April 05, 2009, 09:10:29 AM »

burt i would definately look for one of the old henry consoles.  My amp of choice with my flex 1000 is a henry 2k classic x.  It is the export model.  the specs published a little earlier are what henry claimed but what i observe is 4.1 kv on the plates and under full load 2kw cw dead key the voltage only drops to about 3.9 kv  It truly loafs at 200 watts at 500 carrier i have had the hammer down with about  120% mod and the tubes didnt overheat or change color.  I also have a 5k and recently sold an 8k..  the was just too much and i was offered about 1100 more than they were new and a lot more than  i paid for it.   originally about a $9500 amp.  It would loaf at 1k of carrier.  the only warning i will give about the henrys is that they are louuuuuuuuuuuuud...  fan sounds like i jet turbin with the afterburners on.  the 5k and 8k are coll becuase the have a remote controll pannel that can be used on the end of a 100 ft cord.  My 5k is in the basement and the shack is on the 3rd floor.  oh and one thing about the floor consoles unlike the modern amps these amps have a hv filter choke that is about 3/4 the weight of the main transformer.  in my opinion these were the last of the real amps.
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WQ9E
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« Reply #48 on: April 05, 2009, 09:32:32 AM »


Roger, really nice P.Supply painted to match. Derb, I'm Curious, what did the original supply use to regulate the screen voltage on the 4-100's in linear service, a string of VR tubes?
If so, I guess they're hidden under the covers in the pix you sent.  Rog, VR tubes in yours?

Rick,

Heath put the VR tubes in the RF deck portion, 4 0C-3's and 2 0D-3's.  The external supply provides 3,000 volts and all other voltages are either created or derived in the RF deck.  The power supply I got with mine is a fairly close copy of the original KS-1 and installs using the same plug-in connectors.  The builder used a heftier plate transformer controlled through a 240V Variac and it provides up to 4,000 volts DC.  The rectifier is a solid state bridge feeding a hefty choke and filtering is via a 20 uf oil filled cap.  He also included a plug in control box so that the supply could be used with other amplifiers or transmitters.  The builder/owner did a very nice job and he became a Silent Key a couple of years ago.

The Apache/Mohawk/Chippewa are on the bottom row and the power supply is just out of frame to the right, one of the PS handles is visible.  On the third shelf is probably Heath's lowest power linear, the HA-20, which is the matching 6 meter amp for the HX-30 SSB transmitter.  It only weighs 30 pounds and uses a pair of 6146's to produce 70 watts PEP output.

Rodger WQ9E



* chip.JPG (425.17 KB, 1280x831 - viewed 622 times.)
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Rodger WQ9E
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« Reply #49 on: April 05, 2009, 10:18:28 AM »

Out of curiousity:

How's does the old Hallicrafters HT-33 (with the 4CX PAs)
handle itself on AM duty?  I have one torn down for
restoration... 

Pete
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