Elecraft

Re: [KX3] KX3 and Digital Modea (KM4VX)

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Gary Hawkins

Re: [KX3] KX3 and Digital Modea (KM4VX)

Hi Ron,

I've never run my KX3 on digital as it came out of the box but from the testing I've done I think you're going to struggle with digital until you add a third-party heatsink. I installed the VE7FMN heatsink after experiencing overheating issues running SSB on 10m in California summer weather. I subsequently got into JT65/JT9, and after doing the temperature calibration, the addition of the heatsink is allowing me to run at 10W on 20m and below. Not sure whether this performance can be maintained on the higher frequency bands but at least I'm up and running. I like the KX3 a lot - I've nearly 2000 portable SOTA contacts and I'm rapidly adding digital contacts from the home QTH but it's not perfect. It's a radio that needs a little extra work. IMHO for portable SOTA operation the SideKX by GEM Products is a must and a third party heatsink is a must for digital. I'd love the radio if Elecraft had done this from the outset but they did not and fortunately some good third pa
rty suppliers have neatly solved a couple of significant shortcomings.

73's Gary K6YOA

Message: 3
Date: Mon, 20 Jul 2015 06:28:19 -0700 (MST)
From: KM4VX<[hidden email]>
To:[hidden email]
Subject: [Elecraft] KX3 and Digital Modea
Message-ID:<[hidden email]>
Content-Type: text/plain; charset=us-ascii

I am on my second KX3, having sold the first one and then find myself
missing it. However, I now find the KX3 routinely overheats in digital
modes. Specifically, at just 5 watts on WSPR with transmission time of 2
minutes (as regulated by WSPR software) the KX3 overheats "HI TEMP" at a
minute and a half, resulting in a safety shutdown of the rig. This radio has
a wonderful built-in digital capability, but digital appears beyond the
rig's ability, save CW which is my main digital interest anyway. I would
like to use the KX3 occasionally on PSK, JT65 and WSPR without the absurdity
of having to buy an after-market heat sink to replace a factory installed
heat sink. There is no guarantee the after-market one is superior, and it
shouldn't be necessary since a radio with a digital capability should not
need some after-market accessory to enable the advertised digital mode. I
wonder if anyone has found a firmware or software answer to the over heating
problem. The overheating problem happens regularly in digital modes and I
believe comments about the KX3 working correctly in digital are simply
incorrect. This is not an antenna issue and not an SWR issue.
Thanks Ron
KM4VX

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KM4VX

Re: [KX3] KX3 and Digital Modea (KM4VX)

I have found that the use of an inexpensive computer type fan on even low power running behind the KX3 works well in allowing the full use of the digital modes, to include WSPR at 5 watts full cycle of 112 seconds. Thank you for all the thoughtful inputs. Running WSPR at 3 watts does not require the fan, but at 5 watts the fan is adequate. The radio gets warms, but does not overheat. My KX3 came with the latest heat sink from ElecraftI, have not performed the temperature compensation mod, and will not be buying any after-market heat sink. 73 Ron KM4VX

bs usb

Re: [KX3] KX3 and Digital Modea (KM4VX)

On Thursday, July 23, 2015 03:40:22 PM KM4VX wrote:
> I have found that the use of an inexpensive computer type fan on
even low
> power running behind the KX3 works well in allowing the full use of the
> digital modes, to include WSPR at 5 watts full cycle of 112 seconds.
Thank
> you for all the thoughtful inputs. Running WSPR at 3 watts does not
> require the fan, but at 5 watts the fan is adequate. The radio gets
warms,
> but does not overheat. My KX3 came with the latest heat sink from
> ElecraftI, have not performed the temperature compensation mod,
and will
> not be buying any after-market heat sink. 73 Ron KM4VX

A not so thrifty way of avoiding spending your cash on an aftermarket
heat sink is to spend it on a KXPA100.

Yes, I know you don't need that sort of power for digital modes, but it
does eliminate the need for a bigger heat sink on the KX3 and it
upgrades the KX3 in case you want to run power on SSB or drive a larger
amp to get heard in DX pileups.
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k6dgw

Re: [KX3] KX3 and Digital Modea (KM4VX)

In reply to this post by KM4VX

FWIW and don't know how this would work on a KX3 but ...

When I still had my KPA100 on my K2, and was using the K2/100 in RTTY
contests, I stuck a brushless 12 VDC computer muffin fan to the top of
the heat sink, blowing down, with a little tab of velcro over the PA's.
I have a digital thermometer with a remote sensor on a very small
wire, and I tacked it to one of the PA transistors. I was able to run
in a contest at 100 W and the PA temp stayed well within limits. The
heat sink stayed cool to the touch.

As I said, FWIW. I finally sold the KPA100 and use my K2 as my field
rig with the Alex Loop and no digital now.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015
- www.cqp.org

On 7/23/2015 1:40 PM, KM4VX wrote:
> I have found that the use of an inexpensive computer type fan on even low
> power running behind the KX3 works well in allowing the full use of the
> digital modes, to include WSPR at 5 watts full cycle of 112 seconds. Thank
> you for all the thoughtful inputs. Running WSPR at 3 watts does not require
> the fan, but at 5 watts the fan is adequate. The radio gets warms, but does
> not overheat. My KX3 came with the latest heat sink from ElecraftI, have not
> performed the temperature compensation mod, and will not be buying any
> after-market heat sink. 73 Ron KM4VX

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GM4JJJ

Re: [KX3] KX3 and Digital Modea (KM4VX)

In reply to this post by KM4VX

Ron, the drift reports will be a better on WSPR for you if you do the KX3 extended temperature frequency calibration. Well worth doing it for modes that depend on low frequency drift like WSPR and JT65b.

73

David Anderson GM4JJJ

> On 23 Jul 2015, at 21:40, KM4VX <[hidden email]> wrote:
>
> I have found that the use of an inexpensive computer type fan on even low
> power running behind the KX3 works well in allowing the full use of the
> digital modes, to include WSPR at 5 watts full cycle of 112 seconds. Thank
> you for all the thoughtful inputs. Running WSPR at 3 watts does not require
> the fan, but at 5 watts the fan is adequate. The radio gets warms, but does
> not overheat. My KX3 came with the latest heat sink from ElecraftI, have not
> performed the temperature compensation mod, and will not be buying any
> after-market heat sink. 73 Ron KM4VX
>
>
>

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Alan Bloom

Re: [KX3] KX3 and Digital Modea (KM4VX)

In reply to this post by KM4VX

I used to have fans as one of my categories back when I was employed as
a components engineer at Hewlett Packard. One thing I remember is that
even a small amount of moving air makes a big difference in a heat
sink's thermal resistance. You don't need a huge fan.

Alan N1AL

On 07/23/2015 01:40 PM, KM4VX wrote:

> I have found that the use of an inexpensive computer type fan on even low
> power running behind the KX3 works well in allowing the full use of the
> digital modes, to include WSPR at 5 watts full cycle of 112 seconds. Thank
> you for all the thoughtful inputs. Running WSPR at 3 watts does not require
> the fan, but at 5 watts the fan is adequate. The radio gets warms, but does
> not overheat. My KX3 came with the latest heat sink from ElecraftI, have not
> performed the temperature compensation mod, and will not be buying any
> after-market heat sink. 73 Ron KM4VX
>
>
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/Re-KX3-KX3-and-Digital-Modea-KM4VX-tp7605181p7605261.html
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