The AM Forum
March 28, 2024, 08:41:25 AM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: 1 [2] 3   Go Down
  Print  
Author Topic: Just orderd me a bit of strap  (Read 27975 times)
0 Members and 1 Guest are viewing this topic.
Steve - WB3HUZ
Guest
« Reply #25 on: January 07, 2009, 10:25:12 PM »

Don't worry John. Al is going to build that 813 rig for you.   Grin
Logged
WB2YGF
Guest
« Reply #26 on: January 07, 2009, 10:27:45 PM »

Instead of an 813 leenyar, you could always go this route...

http://www.amwindow.org/tech/htm/813/813.htm

Another one of Tom's great designs.
I am familiar with that schematic, but I heard there are some errors in it. Grin
Logged
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #27 on: January 07, 2009, 10:45:48 PM »


My brain is turning to silicon, John... :-)


Errors on the schematic? Don't worry ~  I hear they hired some guy named Al to fix it up.

T
Logged

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

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
Opcom
Patrick J. / KD5OEI
Contributing
Member
*
Offline Offline

Posts: 8308



WWW
« Reply #28 on: January 08, 2009, 08:42:10 PM »

I'm not sure where the AL-80B dumps its heat, but if you can increase the heat removal, especially past the tube pin and anode seals, it will be alot happier on AM in continuous duty.

Most older amps just fire the hot stuff out the top, and a 10" 220V 'muffin' or "Tarzan" fan sitting up there on little rubber feet is good for them. The 220V makes it quiet on 120V, yet the 10" size moves alot of air out of your expensive amplifier. That's a real nice amp, a good brand for a modern amp and uses a cheap tube to boot.

Sometimes I listen to AM on my rotten little 40FT wire antenna while I am working in the lab. Maybe I will hear you now!
Logged

Radio Candelstein - Flagship Station of the NRK Radio Network.
WB2YGF
Guest
« Reply #29 on: January 10, 2009, 04:41:30 PM »

Well I popped the cover (all 21 screws) and installed the tube.  Looks like I may already have a problem.  The plate supply (no load) is only 2600 instead of the 3100 it's supposed to be.  Line is 120.2.  The transformer is factory set for 125.
Logged
WQ9E
Member

Offline Offline

Posts: 3282



« Reply #30 on: January 10, 2009, 04:54:17 PM »

Might be bad filter caps but it could also be the metering resistors are out of spec.

Logged

Rodger WQ9E
W3NP
Contributing
Member
*
Offline Offline

Posts: 384


WWW
« Reply #31 on: January 10, 2009, 05:15:45 PM »

Well I poped the cover (all 21 screws) and installed the tube.  Looks like I may already have a problem.  The plate supply (no load) is only 2600 instead of the 3100 it's supposed to be.  Line is 120.2.  The transformer is factory set for 125.

It may well be that lower indicated plate voltage is just a result of running on 120 vac instead of 240 and that you are 5 v below the tap setting of 125. Is there a tap for 117 or 120v?
Logged

---Dave  W3NP
WB2YGF
Guest
« Reply #32 on: January 10, 2009, 06:52:57 PM »

It may well be that lower indicated plate voltage is just a result of running on 120 vac instead of 240 and that you are 5 v below the tap setting of 125. Is there a tap for 117 or 120v?
I thought about that, but assuming a linear relationship between input and output voltage, being 5V low on the input (96%) should correspond to 2796.  2600 should correspond to a 104V input.   I have taps for 90, 100, 110, 115, 125 130 & 140.

I can only get about 600 -700 W out, but part of that could be the line dropping to about 105.  The Vplate fully loaded is supposed to be 2700V.
Logged
w8khk
Member

Offline Offline

Posts: 1200


This ham got his ticket the old fashioned way.


WWW
« Reply #33 on: January 10, 2009, 07:54:13 PM »

The line voltage drop of 15 volts (120 - 105) is about 12.5 percent.  If a lower tap (117 or 120) is selected, the line voltage will sag even more, due to larger current draw under load.   Considering this voltage drop, I would assume you may be using a regular 15 amp circuit wired with #14 conductors for the amplifier.   If this is the case, I would recommend either a dedicated 20 amp 120 volt circuit using #12 conductors, (upsize to #10 if it is a rather long run to the panel) or better yet a 20 amp 240 volt circuit, again using # 12 conductors, in this  case no upsize is needed even if it is a rather long run from the panel.

Also it is not clear whether your voltage readings are from the internal meter, or an external calibrated meter.  If you are only using the internal meter, it may not be accurately calibrated, or the multiplier might be high in value.  If you do not have a variac, one way to more safely determine meter calibration is to connect the rig to a 120 volt source, but wire the rig for 240 or 250 volt input.  Then the high voltage meter will read half the expected value, and can be measured with an external calibrated meter in the 1500 volt range.  Still follow all safety precautions, and do not try to load it up with low filament voltage, or better yet, remove the tube when performing the voltage tests.  If you cannot confirm the accuracy of the internal meter, all we know at this point is that you need a source that can handle the current requirements, and there may not be any problem with the actual equipment.
Logged

Rick / W8KHK  ex WB2HKX, WB4GNR
"Both politicians and diapers need to be changed often and for the same reason.”   Ronald Reagan

My smart?phone voicetext screws up homophones, but they are crystal clear from my 75 meter plate-modulated AM transmitter
flintstone mop
Contributing
Member
*
Offline Offline

Posts: 5055


« Reply #34 on: January 10, 2009, 08:01:32 PM »

John
It's a lot more work, but it's worth it. It already looks like your 115VAC is sagging under the load of the amplifier. You should switch to 220VAC.
And the fan, if it's like the Heathkit SB1000 is nothing but a little muffin fan for a microwave oven. That 3-500Z will get very hot in there!!

I have an AL811 made by Ameritron and switching that amp to 220vac DID NOT make any difference in output power. As the manufacturer stated.
But your amp is making 1KW out and you're gonna need more A.C. volts.

200 watts for an A.M. carrier is very rescpectable.

Fred
Logged

Fred KC4MOP
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #35 on: January 10, 2009, 09:09:01 PM »

12 813's in parallel would be an interesting setup; I imagine it would be a little problematic on the higher frequencies with so much output capacitance from the tubes.  As I recall WRL/Galaxy had a 10 or 12 tube 6HF5 amp to match their Mark III or V transceiver and it ran at pretty low plate voltage with the plate current measured in amps resulting in a very low output impedance.   With plate impedance that low you could seriously consider using broadband output transformers similar to those used in modern SS gear.

I started digging out the stuff tonight to build a version of the K1JJ 813 design.  I have a nice Gates roller inductor and a vacuum variable that will soon be living in the output network.  I finally found a mod reactor to go with a WWII era Westinghouse mod transformer I picked up a few years ago.  My plan is to set it up for 160-40 meter operation, 160 in particular.  I have pretty much all of the parts and some chassis from another ham's start at an 813 rig.  My New Year's resolution was to turn more parts into rigs so this is my attempt to keep it.

Rodger WQ9E

Hi Rodger,

Sorry I missed your post the other day.

Yes, that Galaxy amp was something else. I have a friend who actually built a duplicate of it in high school physics class... :-)

The (12) tube 813 linear amp was meant to be used mainly on 160 and 75M, so the plate capacitance wouldn't be an issue. The great thing about that design is silence. For ssb, blower noise is such a pain if you want to run some processing.

Good on the JJ 813 rig you want to build. Sounds like you have a good start with the parts. There's probably at least a dozen rigs out there now in various forms. I like it as a middle of the road rig. I'll tell ya though, one day I'd like to do a quad 813's by quad 813's. Use a 1:1 mod xfmr.  With 3KV on it, it wud be silent and deadly. Or, add the Deitz? lantern chimneys for cooling, with a slight breeze -like mine pictured below. (One 813 final modulated by a pair)

BTW, I built up a great audio driver for the 813 modulators designed by Tom, WA3KLR. It uses about 5 watts TOTAL power and its FET's drive the cathodes of the 813's. Very clean and efficient. The schematic is available if you are interested. Mine is in the little silver box on top of the 813 rig in the pic below.  You need about +50V on the 813 grids to make it work right.

Keep us informed on your new 813 project, Rodger!

John: Your amp.... I doubt it has a problem this early on. It's probably just a matter of getting a stiff AC mains. Though, many pairs of 3-500Z's barely put out 1300W with 2700 V. Maybe a pair will do 1500W pep out with 3KV, so 750W pep out using one is not bad.  So, at your present 600W, an extra 150W is obtainable.  750 pep/4 = 187W carrier, so 150W of carrier might be about right unless you can squeeze more pep out.

I would get in there with a VOM and measure what's coming in at the primary and see how much it sags at full power output.  Definately consider going with 240V. This is something that you need for rigs now and in the future now that you're playing the QRO game... :-)


73,

Tom, K1JJ



* 813 Rig.jpg (585.12 KB, 960x1280 - viewed 462 times.)

* Rigs- 02-28-08 124.jpg (327.34 KB, 1280x960 - viewed 454 times.)

* 4X1Tubes 047.jpg (318.08 KB, 1280x960 - viewed 499 times.)
Logged

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

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #36 on: January 10, 2009, 09:25:20 PM »

Here's the WA3KLR  FET solid state driver. Quite innovative, really.  I use it to drive my 813's modulators. It drives the cathodes and requires about 5W of power. Very efficient. You also need about +50 volts on the 813 grids to get the positive peaks.  One volt in is all it takes.

The schematic is the FIRST file below called, " 833dvr7build.pdf "

Tom, K1JJ

* 833dvr7build.pdf (13.36 KB - downloaded 257 times.)

* 4X1Tubes 019.jpg (321.27 KB, 1280x960 - viewed 519 times.)

* 4X1Tubes 048.jpg (320.48 KB, 1280x960 - viewed 479 times.)
Logged

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

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #37 on: January 10, 2009, 09:41:08 PM »

While we're at it...

Some "before" shots...

T


* 4X1Tubes 037.jpg (322.84 KB, 1280x960 - viewed 465 times.)

* 4X1Tubes 040.jpg (317.05 KB, 1280x960 - viewed 498 times.)

* 4X1Tubes 029.jpg (316.76 KB, 1280x960 - viewed 439 times.)
Logged

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

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #38 on: January 10, 2009, 09:50:54 PM »

Shots of old, never seen before.... :-)


The quad 4X1's are the two finals and two pdm modulators.  Parts all lined up like toy soldiers ready for service.


T


* 4X1Tubes 014.jpg (123.23 KB, 640x480 - viewed 471 times.)

* 4X1Tubes 035.jpg (323.09 KB, 1280x960 - viewed 465 times.)

* 4X1Tubes 050.jpg (320.55 KB, 1280x960 - viewed 405 times.)
Logged

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

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
WB2YGF
Guest
« Reply #39 on: January 11, 2009, 12:10:26 AM »

I am not to concerned with the power sag.  I expected it, particularly when I have the amp plugged into a power strip plugged into an outlet feeding about 5 other power strips (a few computers and other stuff).  Shocked  What does concern me is the low no-load voltage.  The sag issue is irrelevant at no load.  I find it hard to believe the unit would ship with the meter so far out of calibration, but it is possible.  I think I have a HV probe around here somewhere.  If not, I can probably bring home a calibrated HV divider from work. (I work for a HV power supply company, but our stuff is PWM regulated to 0.005%. Wink )
Logged
w8khk
Member

Offline Offline

Posts: 1200


This ham got his ticket the old fashioned way.


WWW
« Reply #40 on: January 11, 2009, 12:18:21 AM »

With that much equipment on a single receptacle, I suspect the wiring and the breaker might get just a bit warm.  Much more important, I would expect any "Old Buzzard" AM transmission to be prematurely extinguished, along with the unsaved computer data. 

I would certainly use a dedicated circuit for any 3-500Z linyear, and if a circuit needs to be added, it would be 240 volts.  Just my two pesos. 
Logged

Rick / W8KHK  ex WB2HKX, WB4GNR
"Both politicians and diapers need to be changed often and for the same reason.”   Ronald Reagan

My smart?phone voicetext screws up homophones, but they are crystal clear from my 75 meter plate-modulated AM transmitter
WB2YGF
Guest
« Reply #41 on: January 11, 2009, 12:24:21 AM »

With that much equipment on a single receptacle, I suspect the wiring and the breaker might get just a bit warm.  Much more important, I would expect any "Old Buzzard" AM transmission to be prematurely extinguished, along with the unsaved computer data. 

I would certainly use a dedicated circuit for any 3-500Z linyear, and if a circuit needs to be added, it would be 240 volts.  Just my two pesos. 
Yeah I know, but I need a 3ft heavy duty extension cord to reach a different outlet for now, and then I can think about running 220V in the future.  Since I am only running about 150W AM to limit the dissipation and maintain linearity, the input power should be fairly modest anyway.
Logged
W1AEX
Un-smug-a-licious
Contributing
Member
*
Offline Offline

Posts: 1488


Apache Labs SDR


WWW
« Reply #42 on: January 11, 2009, 01:05:18 PM »

John,

Just a couple of thoughts regarding the AL-80B. Whenever I move mine on the bench, I have to check the pivots on both cross needle meters. They are sloppy and have a tendency to bind a bit, restricting movement and affecting accuracy. Usually, a little wiggle of the front panel pivot adjustments will free them up. With my unit, the grid current pivot is the one that requires the most attention. This is not an unusual annoyance for any of the Ameritron amps using these meters.

When I first fired up my AL-80B it was wired for 120 vac. The plate voltage initially was sitting at around 2700 vdc with no load and sagged to around 2400 vdc when loaded. It was quite a trick to get much more than 625 watts CW output on any band. I did move the primary tap on the transformer to get it to rest at slightly above 2900, but I still experienced more than 300 volts of sag under load. The maximum output when set up that way was a bit less than 700 watts with CW. The lamps in the room dimmed impressively whenever the amp drew current.

After I ran a dedicated 30 amp 240 vac line up to the station room, the amp performed much better. At idle it typically sits at slightly more than 3000 vdc and under full load will drop to slightly more than 2800. No problem reaching the full rating of 800 watts out with roughly 85 watts of drive (CW) at those voltages. The meter swings to 1000 watts PEP output without any strain. For what it's worth, the PEP meter on the Palstar tuner concurs with that power measurement.

I don't think what you are seeing is at all unusual. If you plan to run the AL-80B on 120 vac for the time being, it might be worth it to move your primary tap to attain a higher plate voltage, closer to 2900 at no load would be good, to allow you to reach higher power at less current.

Incidentally, the internal fan does an excellent job of moving air through the amplifier. I'm not aware of anyone having any heat-related issues with the AL-80B or the 3-500 final as long as there is clearance around the amp for unrestricted air flow. The amp has a decent power supply and in fact the AL-80B is rated for 500 watts output RTTY (1/2 hour continuous carrier duty). Mine has not complained during AM sessions at 125 - 150 watts output, even when I babble longer than anyone cares to listen. I have run it at 200 watts output at times, and it doesn't even flinch then.

Rob W1AEX
Logged

One thing I'm certain of is that there is too much certainty in the world.
WB2YGF
Guest
« Reply #43 on: January 11, 2009, 04:56:33 PM »

When I first fired up my AL-80B it was wired for 120 vac. The plate voltage initially was sitting at around 2700 vdc with no load and sagged to around 2400 vdc when loaded. It was quite a trick to get much more than 625 watts CW output on any band. I did move the primary tap on the transformer to get it to rest at slightly above 2900, but I still experienced more than 300 volts of sag under load. The maximum output when set up that way was a bit less than 700 watts with CW. The lamps in the room dimmed impressively whenever the amp drew current.

I don't think what you are seeing is at all unusual. If you plan to run the AL-80B on 120 vac for the time being, it might be worth it to move your primary tap to attain a higher plate voltage, closer to 2900 at no load would be good, to allow you to reach higher power at less current.
Thank you so much for clearing this up Rob.

On the one hand, this is excellent news because it means the conditions I am seeing are normal.  On the other hand, I am ticked at Ameritron for not putting this information in the manual.  Seems kind of strange they would intentionally get the turns ratio wrong at 125V, but the least they could do is "fess up", particularly when it appears the unit will not make full power as advertised at a typical 120V input line on the 125V tap as shipped.

I was going to get a Variac and take some measurements at reduced voltage, but then I realized that I can't make any sense of the schematic they provide.  They show one stage of the HVDC filter cap circuit completely shorted out.  I can't believe it's actually wired this way.  Has anyone ever done a mark-up of this schematic to make it intelligible?
Logged
flintstone mop
Contributing
Member
*
Offline Offline

Posts: 5055


« Reply #44 on: January 11, 2009, 05:13:59 PM »

OK John
on a temporary hook-up on 115vac, but the P.E.P. might get flat-topped because the H.V. supply is starved for some moe juice.

I was already for 220 operation on my AL811 and the manufacturer said it would be a waste of time...............and it was, as I stated earlier. 3-500Z's need a lot more current than the lowly 811's.

fred
Logged

Fred KC4MOP
ka3zlr
Guest
« Reply #45 on: January 11, 2009, 06:03:30 PM »

As was done here at ZedLR radio I finally after all these years ran a separate 100 amp service to the Xmitter site...and we'll be putting in a 2x1 813 machine in as well...collecting parts now... Smiley
Logged
W4EWH
Member

Offline Offline

Posts: 833



« Reply #46 on: January 11, 2009, 07:05:22 PM »

I know it would work better on 220V, but that's not gonna happen soon.

Check your existing 120V wiring: if any of your outlets have a separate 120 volts feed, it's very easy to reuse the same wire for 220v. This assumes that it's modern wire, such as 12-2 "with ground", but you do not need a separate neutral for a 220V outlet at that current level.

The code requires that the wire be marked at both ends and at any splice points, but that's all: if you have a separate piece of wire already in place, then a double-ganged breaker and a 220V outlet will put you in business.

HTH.

73,

Bill W1AC
Logged

Life's too short for plastic radios.  Wallow in the hollow! - KD1SH
Jim, W5JO
Member

Offline Offline

Posts: 2506


« Reply #47 on: January 11, 2009, 08:00:32 PM »

Don't know about your wiring but usually in a bedroom or utility room there is only one feed of #12 wire for everything.  At most that gives you 15 amps of current for everything in the room.  Given your description of where your amp is gettling AC, it is understandable.

In the kitchen you might see two separate circuits and, again, I don't know about your house.  If it was built many years back it may be wiring challenged, which would explain a lot of sag.

If you have a couple of extra slots in your electrical panel, run a 20 amp 220 V circuit to a dedicated plug and convert the amp to 220.  It, and you, will be much happier and cooler.
Logged
WB2YGF
Guest
« Reply #48 on: January 11, 2009, 08:11:21 PM »

The old section of my house includes the den/computer room/ham shack.  And yes, the entire den is on one 15A breaker.  This section was completely gutted and re-done about 15 years ago when we added a "house" onto our existing "addition", so all the wiring is reletively new. I have a separate 100A sub-panel for this section, so I need to investigate if it is wired for 220V. Unfortunately, all the breaker slots are are filled with 1/2 size breakers.  I have one 20A circuit that is only being used for the basement outlet/dehumidifier and a tiny sump pump.  I might be able to free that up and move the sump pump & dehumidifier over to the dedicated 20A circuit for the washer.

Another option is to run a wire all the way back to the main panel, which unfortunately, has no empty slots.  I think I can change some breakers to 1/2 size to free up some space for a new 220V breaker.  As near as I can tell, the only 220V circuit in the entire house is for the septic pump, as we mostly use oil or propane and have no major appliances which require 220V electric.

BTW, when running 150W of AM, the sag on the line is currently only 2V.
Logged
Opcom
Patrick J. / KD5OEI
Contributing
Member
*
Offline Offline

Posts: 8308



WWW
« Reply #49 on: January 11, 2009, 10:22:24 PM »

While you are at it, why not check to make sure you have 5V at the filament, so it is neither high nor low.
Logged

Radio Candelstein - Flagship Station of the NRK Radio Network.
Pages: 1 [2] 3   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone © 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.069 seconds with 18 queries.