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Author Topic: Pair of 4D32's ... What's the Output Impedence?  (Read 3824 times)
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W2WDX
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« on: December 31, 2009, 03:00:25 PM »
Hi All,

Can't find the data so I'll throw this out there for someone to answer.

What would be the output impedence for a pair of 4D32's in parallel, Class C plate modulated with 675V B+

Trying to match it up with an existing modulator & supply I have.

John
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W7TFO
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IN A TRIODE NO ONE CAN HEAR YOUR SCREEN


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« Reply #1 on: December 31, 2009, 03:13:09 PM »
Just use Ohm's law for the plate voltage and current (X2 for two tubes) and solve for the resistence.  You will get the modulating impedance needed.

73 dg
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N2DTS
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« Reply #2 on: December 31, 2009, 03:37:06 PM »
Better to run them at 800 to 1000 volts.
They seem to modulate much better that way.

At 675 volts, say 360ma per pair, 243 watts in, about 200 watts out, 1875 ohms.

You can run them at higher currents, but the peak modulation seems to fall off, they like higher voltages and less current for the most positive modulation.

I run the 3x4D32 rig at 1200 volts, lots of peak power, 300 watts carrier and close to 1500 watts pep.

Brett
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w1vtp
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« Reply #3 on: December 31, 2009, 04:47:45 PM »
Quote from: N2DTS on December 31, 2009, 03:37:06 PM
Better to run them at 800 to 1000 volts.
They seem to modulate much better that way.

At 675 volts, say 360ma per pair, 243 watts in, about 200 watts out, 1875 ohms.

You can run them at higher currents, but the peak modulation seems to fall off, they like higher voltages and less current for the most positive modulation.

I run the 3x4D32 rig at 1200 volts, lots of peak power, 300 watts carrier and close to 1500 watts pep.

Brett


Yes, Brett -- It's unnerving to know you do that but I've heard you in QSO and that's a FB AM xmtr.  Was it you that said the 4D32 was a poor man's 813?


Nothing poor  about that sig Grin


Al
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N2DTS
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« Reply #4 on: December 31, 2009, 04:57:29 PM »
No, I would say its a rich mans 6146...

Brett
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w1vtp
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« Reply #5 on: December 31, 2009, 08:14:02 PM »
Quote from: N2DTS on December 31, 2009, 04:57:29 PM
No, I would say its a rich mans 6146...

Brett


OH!  I get it.  Honest I did hear it the other way Brent
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KM1H
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« Reply #6 on: January 01, 2010, 01:17:26 PM »
The 814 is a poor mans 813 that loves HV abuse.

The 4D32 is a great tube for a line operated voltage multiplier PS especially when using several.

Carl
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kg8lb
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« Reply #7 on: January 01, 2010, 03:35:57 PM »
Quote from: N2DTS on December 31, 2009, 04:57:29 PM
No, I would say its a rich mans 6146...

Brett


  I have seen NOS 4D32s for $17.00 a pop.In fact, I recently bought 20 of them for $8 each. At the current pricing for good 6146 pairs they could well be a poor man's 6146 !
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