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KX3 Extended VFO temperature compensation procedure

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Phil Wheeler-2

KX3 Extended VFO temperature compensation procedure

Reading the document on this, I get the impression
that the procedure is done wholly within the KX3,
because in the latter "post-refrigerator" part it
says "If the KX3 is connected to a PC running KX3
Utility, data will be sent to the Command Tester
screen." implying the connection to KX3 Utility is
optional.

Is connection to a computer required or optional?

73, Phil w7ox
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Oliver Dröse

Re: KX3 Extended VFO temperature compensation procedure

Optional.

73, Olli

Contest, DX & radio projects: http://www.dh8bqa.de

Am 18.03.2014 01:49, schrieb Phil Wheeler:

> Reading the document on this, I get the impression that the procedure
> is done wholly within the KX3, because in the latter
> "post-refrigerator" part it says "If the KX3 is connected to a PC
> running KX3 Utility, data will be sent to the Command Tester screen."
> implying the connection to KX3 Utility is optional.
>
> Is connection to a computer required or optional?
>
> 73, Phil w7ox
> ______________________________________________________________
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Phil Wheeler-2

Re: KX3 Extended VFO temperature compensation procedure

Thanks, Olli. Starting it now.

73, Phil

On 3/17/14, 5:52 PM, Oliver Dröse wrote:

>
> Optional.
>
> 73, Olli
>
> Contest, DX & radio projects: http://www.dh8bqa.de
>
>
>
> Am 18.03.2014 01:49, schrieb Phil Wheeler:
>> Reading the document on this, I get the
>> impression that the procedure is done wholly
>> within the KX3, because in the latter
>> "post-refrigerator" part it says "If the KX3 is
>> connected to a PC running KX3 Utility, data
>> will be sent to the Command Tester screen."
>> implying the connection to KX3 Utility is
>> optional.
>>
>> Is connection to a computer required or optional?
>>
>> 73, Phil w7ox
>

Phil Wheeler-2

Re: KX3 Extended VFO temperature compensation procedure

Done. It does take more than the nominal 30 min --
more like 90-120 min. But it's done.

Phil

On 3/17/14, 6:36 PM, Phil Wheeler wrote:

> Thanks, Olli. Starting it now.
>
> 73, Phil
>
> On 3/17/14, 5:52 PM, Oliver Dröse wrote:
>>
>> Optional.
>>
>> 73, Olli
>>
>> Contest, DX & radio projects: http://www.dh8bqa.de
>>
>>
>>
>> Am 18.03.2014 01:49, schrieb Phil Wheeler:
>>> Reading the document on this, I get the
>>> impression that the procedure is done wholly
>>> within the KX3, because in the latter
>>> "post-refrigerator" part it says "If the KX3
>>> is connected to a PC running KX3 Utility, data
>>> will be sent to the Command Tester screen."
>>> implying the connection to KX3 Utility is
>>> optional.
>>>
>>> Is connection to a computer required or optional?
>>>
>>> 73, Phil w7ox
>>
>
>

David Pratt

Re: KX3 Extended VFO temperature compensation procedure

In reply to this post by Phil Wheeler-2

And well worth doing too. Drift from 2C to 45C is now less than 5Hz.

73 de David G4DMP

On 18 Mar 2014 03:50, Phil Wheeler <[hidden email]> wrote:
>
> Done. It does take more than the nominal 30 min --
> more like 90-120 min. But it's done.

David Pratt
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Phil Wheeler-2

Re: KX3 Extended VFO temperature compensation procedure

Yes, I'm glad I did it. There was no question I
would eventually.

But 2 deg-C? Did you run a test that low in temp?
I think mine went to 17 deg-C when it came out of
the cooler.

Phil

On 3/17/14, 10:05 PM, David Pratt wrote:
> And well worth doing too. Drift from 2C to 45C is now less than 5Hz.
>
> 73 de David G4DMP
>
> On 18 Mar 2014 03:50, Phil Wheeler <[hidden email]> wrote:
>> Done. It does take more than the nominal 30 min --
>> more like 90-120 min. But it's done.
> David Pratt

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WB4SON

Re: KX3 Extended VFO temperature compensation procedure

Anybody else having issues with non-linear oscillator changes around 40C?
I've done the extended temp calibration 3 times (each time takes about 2
hours), and someplace between 38C and 42C the calibration goes crazy. Up
to that point as the temperature gradually increases the tone shifts lower.
But around that 38-42C spot it start rapidly shifting up in tone and down
in tone (frankly all over the place). When you actually use the KX3 it is
obvious that there is something bad happening around there because you can
hear signals start to wildly drift around in the receiver as the rig temp
moves through that range. That makes me think that the values obtained by
the calibration process are not accurately reflecting true changes in
internal oscillator frequency.

I contacted the factory. Their best advice was to do the calibration again
but use an electronic heat source (like a 50 ohm dummy load) under the KX3
with a variable power supply running the dummy load to get a more linear
temperature increase. I haven't done that yet, but my three prior attempts
have had a pretty linear temperature increase (one changing the rig temp
about 1C per minute from 15C up to 60C).

73, Bob, WB4SON
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73, Bob, WB4SON

Phil Wheeler-2

Re: KX3 Extended VFO temperature compensation procedure

I noticed something similar last night when doing
this. I've not operated since so I don't have any
experience with the result.

At temp of 45 deg or thereabouts the tone started
back up. But it didn't rapidly shift or do
anything bizarre, just increased slowly as the
temp went to 52 deg. Then I locked in the
compensation; have to do RefCal today.

I was surprised that the tone didn't just keep
going down until temp reached 52 deg.

It would be good to know if this is normal or I
need to redo the temp comp procedure (hopefully not).

73, Phil w7ox

On 3/18/14, 7:37 AM, Bob wrote:

> Anybody else having issues with non-linear
> oscillator changes around 40C? I've done the
> extended temp calibration 3 times (each time
> takes about 2 hours), and someplace between 38C
> and 42C the calibration goes crazy. Up to that
> point as the temperature gradually increases the
> tone shifts lower. But around that 38-42C spot
> it start rapidly shifting up in tone and down in
> tone (frankly all over the place). When you
> actually use the KX3 it is obvious that there is
> something bad happening around there because you
> can hear signals start to wildly drift around in
> the receiver as the rig temp moves through that
> range. That makes me think that the values
> obtained by the calibration process are not
> accurately reflecting true changes in internal
> oscillator frequency.
>
> I contacted the factory. Their best advice was
> to do the calibration again but use an
> electronic heat source (like a 50 ohm dummy
> load) under the KX3 with a variable power supply
> running the dummy load to get a more linear
> temperature increase. I haven't done that yet,
> but my three prior attempts have had a pretty
> linear temperature increase (one changing the
> rig temp about 1C per minute from 15C up to 60C).
>
>
> 73, Bob, WB4SON
>

WB4SON

Re: KX3 Extended VFO temperature compensation procedure

Glad to know I wasn't the only one. In my case the issue around 38 to 42C
is a big deal because that is where the PA sits when running JT65. So it
makes that mode unusable. If the odd break didn't happen until 52C I'd be
all set. And it was definitely hopping all over the place (sometimes
rising, other times lowering, and in larger step changes than I was seeing
before).

I'm not so sure this isn't a problem with the radio locking onto a harmonic
of the tone as it shifts lower and lower in pitch. I need to run the test
sometime with a scope on the output to see what the signal looks like as
gets very low in pitch.

Please let us know how it works out when you try it on air.

73, Bob, WB4SON
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73, Bob, WB4SON

Phil Wheeler-2

Re: KX3 Extended VFO temperature compensation procedure

Mine didn't do anything so "wavering" as yours and
it changed at a higher temp. So I wouldn't expect
to see much effect while operating, since it was
at high temps, above 42C.

My concern is if the calibration is off. If it was
a simple linear fit then it could be. If a table
look up or more complex fit then it should still
be good at a normal operating temp range.

73, Phil

On 3/18/14, 8:18 AM, Bob wrote:

> Glad to know I wasn't the only one. In my case
> the issue around 38 to 42C is a big deal because
> that is where the PA sits when running JT65. So
> it makes that mode unusable. If the odd break
> didn't happen until 52C I'd be all set. And it
> was definitely hopping all over the place
> (sometimes rising, other times lowering, and in
> larger step changes than I was seeing before).
>
> I'm not so sure this isn't a problem with the
> radio locking onto a harmonic of the tone as it
> shifts lower and lower in pitch. I need to run
> the test sometime with a scope on the output to
> see what the signal looks like as gets very low
> in pitch.
>
> Please let us know how it works out when you try
> it on air.
>
> 73, Bob, WB4SON
>

Phil Wheeler-2

Re: KX3 Extended VFO temperature compensation procedure

Also -- I haven't done any digital/data modes with
my KX3 as yet, and may not (have a K2/100 and a
K3/100 which may be more favorable for that than a
barefoot KX3). However, I do have a SignaLink USB
with cables for the KX3 so I may eventually use it
that way portable if the opportunity arises.

I suspect the thermal conditions will stay pretty
benign in CW and SSB modes.

73, Phil w7ox

On 3/18/14, 9:43 AM, Phil Wheeler wrote:

> Mine didn't do anything so "wavering" as yours
> and it changed at a higher temp. So I wouldn't
> expect to see much effect while operating, since
> it was at high temps, above 42C.
>
> My concern is if the calibration is off. If it
> was a simple linear fit then it could be. If a
> table look up or more complex fit then it should
> still be good at a normal operating temp range.
>
> 73, Phil
>
> On 3/18/14, 8:18 AM, Bob wrote:
>> Glad to know I wasn't the only one. In my case
>> the issue around 38 to 42C is a big deal
>> because that is where the PA sits when running
>> JT65. So it makes that mode unusable. If the
>> odd break didn't happen until 52C I'd be all
>> set. And it was definitely hopping all over
>> the place (sometimes rising, other times
>> lowering, and in larger step changes than I was
>> seeing before).
>>
>> I'm not so sure this isn't a problem with the
>> radio locking onto a harmonic of the tone as it
>> shifts lower and lower in pitch. I need to run
>> the test sometime with a scope on the output to
>> see what the signal looks like as gets very low
>> in pitch.
>>
>> Please let us know how it works out when you
>> try it on air.
>>
>> 73, Bob, WB4SON
>>
>
>

W6NF

Re: KX3 Extended VFO temperature compensation procedure

I have been following this thread with interest.

Given our change in living arrangements, from a house with plenty of
space for antennas to an apartment with no place for antennas, we are
forced to do mobile and portable operation. In that case we can no
longer easily operate our K3/P3 and have been considering getting a KX3
instead. This thread causes me to wonder if this would be a good idea
since one of the things we would want to do, while operating portable,
are various digital modes, including JT65.

Is this VFO temperature compensation problem serious enough to make
reconsidering the KX3 wise?

Thanks,

Jack, W6NF/VE4SNA

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Phil Wheeler-2

Re: KX3 Extended VFO temperature compensation procedure

At this point I wouldn't characterize my
experience as a concern. So far as I can tell the
calibration worked well, though I was surprised to
see the tone vs. temp behavior above about 45
deg-C. My impression is that the calibration is
done with a table, so such nonlinear behavior
should not be an issue, so long as it is
repeatable. The post by Bob, WB4SON early today in
this thread described some "crazy" behavior which
would concern me.

Of more concern in such modes might be the power
limitation at higher temps. There is some
temperature at which the PA power will be limited.
I don't know if that limit is of concern for JT65
operation or not. I know there have been
discussions in the Yahoo KX3 group about different
ways to add cooling to the KX3 for portable ops --
including fans, larger heat sinks with fins, and
in one case leaning a cold cooler against the rig.

73, Phil w7ox

On 3/18/14, 11:39 AM, Jack wrote:

>
> I have been following this thread with interest.
>
> Given our change in living arrangements, from a
> house with plenty of space for antennas to an
> apartment with no place for antennas, we are
> forced to do mobile and portable operation. In
> that case we can no longer easily operate our
> K3/P3 and have been considering getting a KX3
> instead. This thread causes me to wonder if this
> would be a good idea since one of the things we
> would want to do, while operating portable, are
> various digital modes, including JT65.
>
> Is this VFO temperature compensation problem
> serious enough to make reconsidering the KX3 wise?
>
> Thanks,
>
> Jack, W6NF/VE4SNA

Dominic Baines-3

Re: KX3 Extended VFO temperature compensation procedure

Having run my KX3 in 40'C ambient temp just for ssb or cw and the odd
bit of data and seem high pa temps and the kx3 folding back you
absolutely have to consider better/decent cooling if you seeing pa temps
consistently at this level.

You trying to run at 10W non stop then wind the power levels down?
Running at this level with high temps is a bad idea without better cooling.

A simple extra external heatsink can be added to the current heatsink
plate, with or without fan cooling and that should make a huge difference.

Or

Use the KX3 at 1-3 W and add a PA.

72

Dom
M1KTA

On 18/03/2014 19:19, Phil Wheeler wrote:

> At this point I wouldn't characterize my experience as a concern. So
> far as I can tell the calibration worked well, though I was surprised
> to see the tone vs. temp behavior above about 45 deg-C. My impression
> is that the calibration is done with a table, so such nonlinear
> behavior should not be an issue, so long as it is repeatable. The post
> by Bob, WB4SON early today in this thread described some "crazy"
> behavior which would concern me.
>
> Of more concern in such modes might be the power limitation at higher
> temps. There is some temperature at which the PA power will be
> limited. I don't know if that limit is of concern for JT65 operation
> or not. I know there have been discussions in the Yahoo KX3 group
> about different ways to add cooling to the KX3 for portable ops --
> including fans, larger heat sinks with fins, and in one case leaning a
> cold cooler against the rig.
>
> 73, Phil w7ox
>
>
> On 3/18/14, 11:39 AM, Jack wrote:
>>
>> I have been following this thread with interest.
>>
>> Given our change in living arrangements, from a house with plenty of
>> space for antennas to an apartment with no place for antennas, we are
>> forced to do mobile and portable operation. In that case we can no
>> longer easily operate our K3/P3 and have been considering getting a
>> KX3 instead. This thread causes me to wonder if this would be a good
>> idea since one of the things we would want to do, while operating
>> portable, are various digital modes, including JT65.
>>
>> Is this VFO temperature compensation problem serious enough to make
>> reconsidering the KX3 wise?
>>
>> Thanks,
>>
>> Jack, W6NF/VE4SNA
>