I run an Astron 50 amp linear supply and a 4' cord between it and the K2
I see .6 of a volt drop on keydown at 100 watts
From: James Bennett <[email protected]>
To: Elecraft Reflector Reflector <[email protected]>
Sent: Thursday, March 9, 2017 8:09 PM
Subject: [Elecraft] K3 Power Supply Question
Hi All -
I’ve been powering my station for anywhere from 7 - 9 years (can’t recall
exactly how long!) with an MFJ4245MV switching power supply. I use it in
conjunction with a 72 watt GE solar panel, 110 Ah AGM battery, ProStar charge
controller, N8XJK Boost Regulator, and a KI0BK Low Loss PowerGate. All cables
have been fitted with multiple mix 31 ferrite dounts with multiple wraps - I’ve
got pretty much NO RF hash on any of the HF bands on the K3 or my KX3. All the
above power equipment feeds into a Rig Runner 4008. Anderson PowerPole
connectors connect to as short as possible #12 cable to several devices: K3,
P3, KX3, PX3, KXPA100, and a home brew W6PQL 2 meter all mode amp.
Haven’t had any issues with the above configuration. Until today, when I
happened to punch the K3 DISP button, changing it from reading my VFO B
frequency to the other various bits of information. One of them was the rig
voltage. Sitting there on 17 meters in CW mode receive it was showing a nice
13.8V. Cool. I hit the key and - wait a minute…… it dropped way down to 12.4v.
Huh - not so cool. My first thought was that the Boost Regulator was not doing
it’s job. But I decided to start trouble shooring at ground zero - the MFJ
4245. I disconnected it from the Power Gate and ran it directly to the K3. Key
up = 13.8V. Key down = 12.0V. Yikes! I think (IMHO) calling this poor
regulation (15%) would be a gross understatement.
Am I wrong for expecting a desk power supply to do better than this? I had
purchased this 4245 years ago because the price was right AND that it can run
on 117 or 220 volts. At one time I had been contemplating a move to the
Philippines and a 220v supply would be needed. By the way, nothing else running
here in the shack other than a computer which was in sleep mode anyway, so line
voltage sag likely is not the issue.
So, if this this a common problem with the MFJ stuff, what other 25+ amp
supplies are folks using with their K3’s that have better regulation than 15%?
Jim / W6JHB
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