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K2DC
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« Reply #1 on: August 03, 2012, 02:54:06 AM » |
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Wow! Clean and simple. Hard to beat that.
73,
Don, K2DC
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W1QJ
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« Reply #2 on: August 03, 2012, 03:40:49 AM » |
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Ha, that's funny, Ray waited for Pat to hang it up and then copies the HF-2500 with an 8877 instead of 2 3CPX800 tubes. That is a clone of that amp. I guess he put an access door underneath to get to the power supply. Hope he did. When it goes out of warranty I'll be glad to repair these. Nothing new here in this baby. Even the control board looks the same. Maybe Pat sold his old partner what was left of his stock. |
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N4RSS
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« Reply #3 on: August 03, 2012, 06:36:41 AM » |
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Ha, that's funny, Ray waited for Pat to hang it up and then copies the HF-2500 with an 8877 instead of 2 3CPX800 tubes. That is a clone of that amp. I guess he put an access door underneath to get to the power supply. Hope he did. When it goes out of warranty I'll be glad to repair these. Nothing new here in this baby. Even the control board looks the same. Maybe Pat sold his old partner what was left of his stock. Or maybe he drew heavily from his own HF-2500DX whose power supply is accessible through the top |
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NO2A
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« Reply #4 on: August 03, 2012, 09:14:42 AM » |
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The dual 3-500ZG amp doesn`t deliver full output in cw no matter how hard you drive it. The HF-2500 draws 25 amps? That seems excessive for 1500 watt output. Curious what the `8877 draws.
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WB2WIK
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« Reply #5 on: August 03, 2012, 09:23:29 AM » |
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Ha, that's funny, Ray waited for Pat to hang it up and then copies the HF-2500 with an 8877 instead of 2 3CPX800 tubes. That is a clone of that amp. I guess he put an access door underneath to get to the power supply. Hope he did. When it goes out of warranty I'll be glad to repair these. Nothing new here in this baby. Even the control board looks the same. Maybe Pat sold his old partner what was left of his stock. I must be missing something. The "3KDX" photos don't show a tuned input circuit anywhere. WTF?  |
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K8AXW
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« Reply #6 on: August 03, 2012, 09:28:01 AM » |
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Absolutely a work of art! One fault I see with the 3-500 amp is the cooling method. The fan (shades of Heathkit SB-220) blows hot air from on tube onto the second tube before exiting the enclosure.
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N4RSS
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« Reply #7 on: August 03, 2012, 09:36:39 AM » |
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The dual 3-500ZG amp doesn`t deliver full output in cw no matter how hard you drive it. The HF-2500 draws 25 amps? That seems excessive for 1500 watt output. Curious what the `8877 draws.
I think I have 25 amp fuse in mine and pushes 2400 into a dummy load |
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N4RSS
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« Reply #8 on: August 03, 2012, 09:37:55 AM » |
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Ha, that's funny, Ray waited for Pat to hang it up and then copies the HF-2500 with an 8877 instead of 2 3CPX800 tubes. That is a clone of that amp. I guess he put an access door underneath to get to the power supply. Hope he did. When it goes out of warranty I'll be glad to repair these. Nothing new here in this baby. Even the control board looks the same. Maybe Pat sold his old partner what was left of his stock. I must be missing something. The "3KDX" photos don't show a tuned input circuit anywhere. WTF? I didn't see any filter capacitors either in any of the pictures |
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W1QJ
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« Reply #9 on: August 03, 2012, 09:57:29 AM » |
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Ha, that's funny, Ray waited for Pat to hang it up and then copies the HF-2500 with an 8877 instead of 2 3CPX800 tubes. That is a clone of that amp. I guess he put an access door underneath to get to the power supply. Hope he did. When it goes out of warranty I'll be glad to repair these. Nothing new here in this baby. Even the control board looks the same. Maybe Pat sold his old partner what was left of his stock. I must be missing something. The "3KDX" photos don't show a tuned input circuit anywhere. WTF? Looks like a broad band input to me. never saw that before with an 8877, ok, so the rest is pretty much the same. |
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G3RZP
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« Reply #10 on: August 03, 2012, 10:28:52 AM » |
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Filter caps under the rectifier board. Tuned input adjustments visible in the rear panel shot.
But what gives with FCC Part 15 compliance notice on the back? What is that needed for? An amp that big 'must not cause interference' indeed!
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K0CWO
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« Reply #11 on: August 03, 2012, 11:31:02 AM » |
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"The dual 3-500ZG amp doesn`t deliver full output in cw no matter how hard you drive it."
What dual 3-500ZG amp are you referring to?
I have a QRO HF-2000 with RF Parts 3-500ZG's in it that are two years old. The following is what I get on 40 meters (7.2 MHz) driving the HF-2000 with 95 watts RTTY/CW from a Yaesu FT-950 into a Palstar DL2K dummy load:
4150 plate volts at idle
3750 plate volts under load (95 watts of RTTY/CW drive). That produces 800 mills of plate current (3750 X .8 = 3000 watts input).
Seems to deliver full output to me using a 50% efficiency figure.
I don't have any lab accurate watt meters here but my Palstar AT5K and Ameritron AWM-35 certainly indicate 1500 watts out with the above scenario.
For what it is worth.
73, k0cwo
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NO2A
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« Reply #12 on: August 03, 2012, 12:20:26 PM » |
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I was referring to the specs for the HF-2000. They claim 1500 output for ssb but 1200 for cw. Might just be a typo.
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K0CWO
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« Reply #13 on: August 03, 2012, 12:26:04 PM » |
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I see. Lots of things in some of these manuals don't jive . 73, k0cwo |
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W1QJ
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« Reply #14 on: August 03, 2012, 01:15:14 PM » |
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Are you sure about that 4150v idle plate current? Are you sure it's not 3150 and 2700 you mean.?
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