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Author Topic: Amp Supply LK-500B questions.  (Read 630 times)
KB8ASO
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Posts: 71




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« on: April 06, 2008, 07:07:10 AM »

Since the owner of Omega is now SK, who is now the best source of info and parts? Anyone taking over Omega? I have read here that there is some kind of tube protection on the "B" version and more on the "C". I see nothing on the schematic and nothing mentioned in the manual. Can anyone clarify this please???

Thank you,
Randy AB9GO
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W1QJ
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Posts: 1445




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« Reply #1 on: April 06, 2008, 12:07:47 PM »

The Lk-500 (A) (B) (c) models are pretty much all the same amplifers "rf wise". The B has some protection circuits and the C has even more protection circuits.  The A has none that I know of.  Other than that there is very little difference.  Some models were offered with QSK.  Lou
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KB8ASO
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Posts: 71




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« Reply #2 on: April 06, 2008, 05:39:17 PM »

That is what I understand is that the "B" series had some kind of protection and the "C" series even more.  Does someone know what the protection is/was.  The schematic is no help.  This manual should be required reading in a course on technical documentation as a prime example of poor documentation and the issues raised by it.  

Randy AB9GO    
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KB8ASO
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« Reply #3 on: April 06, 2008, 05:42:59 PM »

p.s.  I have the QSK model.
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W1QJ
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« Reply #4 on: April 06, 2008, 10:37:46 PM »

I am not 100% certain, but the Lk-500A model had no protection circuits, much like an Sb-220.  The "B" model incorporated a high grid and I think a High plate current shut down protection crcuit.  The "C" model went beyond the B to also include high swr shut down.  The QSK might have been a "standard" on the C model as well not sure.  The basic schematic of all all 3 amps are the same except for the protection circuitry which most of it was on PC boards.  Troubleshooting any "RF" problem can be done with the basic schematic.  If the protection circuits are acting up, you would need the schematic for that model.
Lou
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N4AWP
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Posts: 21




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« Reply #5 on: April 09, 2008, 07:02:09 AM »

I have a "C" model with QSK. It also has a High / Low switch for the fan. The fan is very loud and am trying to find a replacement without much luck. Can you help?? It is a Nidec Alpha V TA450 Model A 30045-10 fan. It is two speed , 117VAC @ .26/.21amp.
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KB8ASO
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Posts: 71




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« Reply #6 on: April 09, 2008, 08:07:06 AM »

Hello,  My 500B uses a 120 V single speed fan, but with a resistor in one leg of the AC feed.  You can use a standard fan with this arrangement and get two speeds by putting a switch across the resistor.  The resistor on my schematic is R4 250 ohm @ 10 watts.  You are going to have a hard time finding a two speed fan either surplus or off the shelf @ a supplier as they were not commonly used.  

Question.  Do you have a scanner and if so would you please scan the schematic and parts list of your 500C?
My Email address is randallr@healthall.com

Thank you,
Randy.
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N4AWP
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Posts: 21




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« Reply #7 on: April 10, 2008, 01:05:28 PM »

Thanks for the info. Makes sense now. I do not have a schematic or parts list. I need the the same as you. If I find one I will let you know and you the same.
tnx Art
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KB8ASO
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Posts: 71




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« Reply #8 on: April 10, 2008, 05:06:37 PM »

Thanks.  I'll send you the "C" schematic as soon as I find one.  From what I am finding out the Amp Supply amplifiers were a continual work in progress.  Many have said that the correct exact schematic for many of the LK series simply does not exist.  Modification of the circuits was ongoing and continual.  I'll send you what I can find.

Randy AB9GO  
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N4AWP
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Posts: 21




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« Reply #9 on: April 13, 2008, 04:35:46 AM »

Thanks Randy.
I will send you what I have.

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