Hi Mark,
Thanks, this seems to be the best explanation as to why the Hi Cur
warning is happening.
I'm now trying to decide whether to go for LifePo or LiPo. I like fact
LiPo have higher voltage per cell thus creating a nominal working
voltage around 14.8V but I will likely go for LifePo (nominal working
voltage 13.2V) since they seem a lot safer during charging process.
Gary
KK6GXD
On 12/13/2013 10:01 AM, Mark Petiford wrote:
Gary,
I didn't find the table, but I did find two relevant posts:
This was the problem reported by one poster:
>>During xmit at modest power 8 - 9 watts, I occasionally see a msg
flash on the display that shows "hi curr". It seems that when that
happens, the xmit power gets reset to 5.0 watts. I have the battery
charger option installed and NiMH batteries in the unit, but have been
running from an external 12v gel cell.
Sounds quite similar to your experience. There was a response from
Myron, WV0H, who has done considerable testing on his KX3:
>>8-9V will allow you 3W on any band.
>>9-11V will allow you 5W on any band.
>>11-13V will allow you 10W on 160-15m, 8W on 12-6m, and HI CURR if
you exceed 2.5A.
>>13-15V will allow you 12W on 160-15m and HI CURR if you exceed 3.0A,
or if on 12-6m HI CURR
if you exceed 2.5A.
>>If the HI CURR warning shows up, expect to see the power setting
throttled back.
I have tested some of these data points and my results are very
similar to Myron's. In addition, I took a look at some SLA datasheets,
and would be very surprised if the voltage at the KX3 during transmit
stays above 11v for long. The discharge curve (NOT the same thing as
the resting curve, or the charge curve) for SLA's is pretty steep.
Combine that with the relatively high internal resistance of the
cells, cable/connector drop, and the KX3's reverse polarity
protection, and the voltage at the KX3's Power Amplifier tends to get
knocked down a lot. I ran successfully ran SLA's for a while after
receiving my KX3, but only at 5w and below.
I suspect your decision to move to Lifepo/Lipo cells is the right
answer if you want to stay in the 8-10 watt range. There are lots of
folks using them successfully for that reason.
Mark
KE6BB
From: Gary [email protected]>
Sent: Fri, Dec 13, 2013 at 9:04 AM
To: Mark Petiford [email protected]>; [email protected]
[email protected]>
Subject: Re: [Elecraft] [KX3] Hi Curr Warning
Hi Mark,
I have revision C2 of the manual and, if I remember correctly,
theimportant power voltage setting is >11V for full power. Thatbeing
said, if 13.8V is what is required this may explain what'sgoing on.
The SLA nominal voltage is marginal. I'm going topurchase some
Lifepo/Lipo batteries to both reduce weight in packand provide a
slightly higher nominal voltage.
I'm not a member of the Yahoo KX3 user group - perhaps I shouldjoin.
If you do find the table you referenced I'd love to see it.
Best regards,
Gary
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