Re: [Elecraft_K3] K3 Voltage Drop

Dennis Ashworth
 

I just adjusted the voltage on my RS35 ... easy - very intuitive once you removed the top covers
Dennis, K7FL


On Wed, Apr 10, 2013 at 8:12 PM, Richard Fjeld <rpfjeld@...> wrote:
 

As I recall, the Astron 35M has an adjustment pot for voltage, but it is on the bottom of the board with very little clearance.  It is the reason why I have not increased my voltage.  I keep hearing Murphy saying;  "If it ain't broke, don't fix it."
 
Rich, n0ce
 
 
----- Original Message -----
Sent: Wednesday, April 10, 2013 12:53 AM
Subject: RE: [Elecraft_K3] K3 Voltage Drop

 

I believe your Astron is adjustable internally. If not a search of the Internet will review where to add a cal pot.

73, Fred, AE6QL

From: Elecraft_K3@... [mailto:Elecraft_K3@...] On Behalf Of James Rossell
Sent: Tuesday, April 09, 2013 8:30 PM
To: Elecraft_K3@...
Subject: Re: [Elecraft_K3] K3 Voltage Drop

 

Excellent ! Now I need an adjustable PS. No Problem.

Thanks for the response.  Case closed.


73, Jim


From: Fred Townsend <fptownsend@...>
To: Elecraft_K3@...
Sent: Tuesday, April 9, 2013 12:59 PM
Subject: RE: [Elecraft_K3] K3 Voltage Drop

 

James I waited to let others to answer your question but I’m not seeing a real answer.

Yes, your readings are normal, well almost. The K3 does not measure the voltage at the input terminal and I think 0.2v difference is normal and it does not change much from transmit to receive. However your cable drop is based upon IR losses and it will drop on transmit.

Your numbers illustrate how easily power can be lost in a low voltage, high current situation. Furthermore these systems deteriorate very quickly and require monitoring to make sure some terminal doesn’t go bad. It’s simple to do. Just touch your power terminals after you have been in a long QSO. If you find a warm one investigate.

Check your input voltage specifications for the K3 and you will find you may increase the input voltage well about 14.0V. It may seem counterintuitive but your K3 will run cooler if you increase voltage. Before you increase anything make sure a higher input voltage setting on your power supply is compatible with your other 12 volt loads.

73, Fred, AE6QL

From: Elecraft_K3@... [mailto:Elecraft_K3@...] On Behalf Of James Rossell
Sent: Monday, April 08, 2013 6:19 PM
To: Elecraft_K3@...
Subject: [Elecraft_K3] K3 Voltage Drop

 

I  never noticed this before but wonder if this is normal.  I am using an Astron RS-35M.

I measure 13.88 volts at the terminals. A small amount of possible meter error.

At the K3  Power Pole connector I measure 13.39 Volts while transmitting 65 Watts.

The K3 Volt Meter shows 12.7 Volts.

The cable is about of10 feet long of stranded #12. 

Cleaned the fuse holders and replaced the fuses.

That is a 0.49 voltage  drop.

The K3 initially shows 13.8 Volts but when transmitting it reads 12.7 Volts.

That is a 0.69 Volt drop from the 13.39 Volts read at the Power Pole connector at the K3.

Is this normal  when transmitting to see the Volt Meter in the K3 to show a Voltage drop?

The K3 works just fine getting good output.

Hope I explained things well. I appreciate any and all comments.

Jim, KQ3R


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