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Author Topic: Henry K-2000 amplifier  (Read 20730 times)
N0SQ
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« on: April 01, 2017, 12:51:58 PM »

I just got donated this amplifier and have one question, for now. That is: do I need a relay buffer between my Kenwood TS2000 and this amplifier? The manual that I have isn't clear on that.
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W1QJ
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« Reply #1 on: April 01, 2017, 01:42:31 PM »

Is this the amp thta has Two (2) 8873 tubes?  It should have a heat sink on the back.  Is that the one?  Do you have a manual?
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N0SQ
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« Reply #2 on: April 01, 2017, 01:44:29 PM »

Is this the amp thta has Two (2) 8873 tubes?  It should have a heat sink on the back.  Is that the one?  Do you have a manual?

That's the one. I do have a manual.
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W1QJ
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« Reply #3 on: April 01, 2017, 02:10:59 PM »

OK great, can you tell from the manual what the antenna relay voltage is?  Perhaps from the schematic?  Compare the relay voltage to what the TS-2000 can handle and that should tell you if you need an interface.
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N0SQ
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« Reply #4 on: April 01, 2017, 03:01:26 PM »

OK great, can you tell from the manual what the antenna relay voltage is?  Perhaps from the schematic?  Compare the relay voltage to what the TS-2000 can handle and that should tell you if you need an interface.

The amplifier relay is 12 VDC and the TS2000 does 12 VDC @ 10mA - it's actually a switch between open and ground.
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W1QJ
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« Reply #5 on: April 01, 2017, 04:23:33 PM »

OK great, can you tell from the manual what the antenna relay voltage is?  Perhaps from the schematic?  Compare the relay voltage to what the TS-2000 can handle and that should tell you if you need an interface.

The amplifier relay is 12 VDC and the TS2000 does 12 VDC @ 10mA - it's actually a switch between open and ground.
 

NO NO NO NO.......The Remote jack is used to activate an external amplifier.  The ground connection of the linear amp antenna cable goes to PIN2 and the center conductor goes to PIN 4.  When you key the radio pin 2 and 4 come together and turns on the amp relay.  Unfortunately there are no specs given on what that relay in the radio can handle. Being a relay and not a transistor (on HF) it should easily handle 12 volts at I'd say 500ma most likey.  I would make sure the antenna relay has a quench diode across the coil.  The 12v you refer to at 10ma is a signal output not a switch contact.  You don't want voltage comig to the relay, you just want a contacts coming together.  So use PIN2 and PIN4.
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N0SQ
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« Reply #6 on: April 01, 2017, 05:54:32 PM »

OK great, can you tell from the manual what the antenna relay voltage is?  Perhaps from the schematic?  Compare the relay voltage to what the TS-2000 can handle and that should tell you if you need an interface.

The amplifier relay is 12 VDC and the TS2000 does 12 VDC @ 10mA - it's actually a switch between open and ground.
 

NO NO NO NO.......The Remote jack is used to activate an external amplifier.  The ground connection of the linear amp antenna cable goes to PIN2 and the center conductor goes to PIN 4.  When you key the radio pin 2 and 4 come together and turns on the amp relay.  Unfortunately there are no specs given on what that relay in the radio can handle. Being a relay and not a transistor (on HF) it should easily handle 12 volts at I'd say 500ma most likey.  I would make sure the antenna relay has a quench diode across the coil.  The 12v you refer to at 10ma is a signal output not a switch contact.  You don't want voltage comig to the relay, you just want a contacts coming together.  So use PIN2 and PIN4.

My bad. You're right. The remote cable that I'm using was originally built when I had an AL-811H. Same cable, same rig, different amplifier. The RCA cable that I'm using is connected to the TS2000 REMOTE connector pins 2 and 4 just as you said. The only question is whether or not the rig can sink the current.  My guess is if the rig worked with the AL-811H it should work with this "new" amplifier. If my ohmmeter readings are correct, the amplifier relay winding measures 140 ohms so the current draw will be about 85 mA. According to the amplifier schematic, the amplifier relay doesn't have the diode across its windings like the AL-811H did.
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W1QJ
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« Reply #7 on: April 01, 2017, 06:23:12 PM »

The radio relay should easily handle that relay.  Just put a diode 1n4007 across the coil
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N0SQ
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« Reply #8 on: April 02, 2017, 07:37:36 AM »

Is it possible to replace the BeO blocks in this amplifier with something "safer"? Such as Aluminum Nitride?
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N0SQ
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« Reply #9 on: April 02, 2017, 07:39:59 AM »

The radio relay should easily handle that relay.  Just put a diode 1n4007 across the coil

It's not a trivial matter to add this diode. Looks like I have to take apart a lot of stuff to get to the coil winding terminals. I'm considering alternatives.
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W1QJ
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« Reply #10 on: April 02, 2017, 07:41:57 AM »

Is it possible to replace the BeO blocks in this amplifier with something "safer"? Such as Aluminum Nitride?

BeO is only unsafe when it is crumbled, sanded or chipped etc.  As it is in the amp it is safe, no need to do anything.
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N0SQ
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« Reply #11 on: April 02, 2017, 07:46:39 AM »

Is it possible to replace the BeO blocks in this amplifier with something "safer"? Such as Aluminum Nitride?

BeO is only unsafe when it is crumbled, sanded or chipped etc.  As it is in the amp it is safe, no need to do anything.

That's my understanding. It doesn't look like it'll be easy to accidentally chip it and I certainly won't sand and/or drill it. I've also noticed that this amplifier doesn't have an interlock switch. I probably won't need it but it wouldn't hurt to add one (if possible).
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W1QJ
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« Reply #12 on: April 02, 2017, 07:52:00 AM »

Is it possible to replace the BeO blocks in this amplifier with something "safer"? Such as Aluminum Nitride?

BeO is only unsafe when it is crumbled, sanded or chipped etc.  As it is in the amp it is safe, no need to do anything.

That's my understanding. It doesn't look like it'll be easy to accidentally chip it and I certainly won't sand and/or drill it. I've also noticed that this amplifier doesn't have an interlock switch. I probably won't need it but it wouldn't hurt to add one (if possible).

Well safety  is always a good thing.  Some amps have two safety methods, an interlock and a HV shorting circuit that grounds the HV if the lid is off.  Some amps only have one or the other and others have nothing.  Since I am the only one that works on my amps I take necessary precautions always even though some of the amps have no interlocks.
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N0SQ
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« Reply #13 on: April 02, 2017, 01:10:13 PM »

Does anyone know of a source for a rocker power switch for this amplifier? So far, I've found rockers that are physically too small or too large. Of course, I could do a mod to make them work but if someone knows of a rocker that will fit the existing cutout please let me know.
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AE0Q
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« Reply #14 on: April 03, 2017, 07:42:58 AM »

I just got donated this amplifier and have one question, for now. That is: do I need a relay buffer between my Kenwood TS2000 and this amplifier? The manual that I have isn't clear on that.

Lee, I think another question is, do you really want to use that amp (8873 tubes) on RTTY ?  Watch the grid current.

Glenn AE0Q
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Glenn and V-NATCH Katie,
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