KX3 OSC Temp And Freq Drift Relationship?

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KX3 OSC Temp And Freq Drift Relationship?

Jack Chomley
Tonight I have been experimenting on PSK31 at 3 watts and 5 watts. In my shack the OSC Temp is about 38 deg and transmitting my CQ call about every 60 seconds @ 3 watts takes the OSC Temp to 39 deg, on RX it drops back to 38 deg.
At 5 watts it goes up to 41 deg, but immediately settles back to 38 deg.
My question is, what would the estimated frequency change be, per degree of OSC Temp change? I am trying to work out the total freq shift between the start and the end of my PSK31 transmission.
Now, I have not done the OSC temp compensation routine to my radio. Trying not to go down this road in case I make a hash of it :-)
In closing, I will not be using WSPR or JT65 etc with this radio.


73,

Jack VK4JRC

Club.    www.cqara.org.au
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Re: KX3 OSC Temp And Freq Drift Relationship?

Don Wilhelm-4

I can't answer your question without measuring your particular KX3, and
about the only thing I can do is quote the specification of +/- 1 ppm
over 0 to 50 degC.  You can better that with the Temp Compensation.

I don't think doing the Temperature Compensation will make a 'hash' of
anything, but if you have such fears, save the configuration before you
do that.  It is a time consuming process, but it is not difficult.  Plan
about 2 hours to accomplish that process - you don't even have to open
the KX3.

73,
Don W3FPR

On 3/26/2014 8:59 AM, Jack Chomley wrote:
> Tonight I have been experimenting on PSK31 at 3 watts and 5 watts. In my shack the OSC Temp is about 38 deg and transmitting my CQ call about every 60 seconds @ 3 watts takes the OSC Temp to 39 deg, on RX it drops back to 38 deg.
> At 5 watts it goes up to 41 deg, but immediately settles back to 38 deg.
> My question is, what would the estimated frequency change be, per degree of OSC Temp change? I am trying to work out the total freq shift between the start and the end of my PSK31 transmission.
> Now, I have not done the OSC temp compensation routine to my radio. Trying not to go down this road in case I make a hash of it :-)
>

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Re: KX3 OSC Temp And Freq Drift Relationship?

Jim Bennett
In reply to this post by Jack Chomley
Jack,

My KX3 #5539 is used on and off for PSK31 and JT9 / JT65. I've made a bunch of JT65 and JT9 QSO's with it on 80, 20, and 10 meters, in addition to quite a few PSK31 contacts on several bands. That being said, I did do the temperature compensation procedure before I started doing data JT9 and JT65 modes with the KX3. As Don said, it is a very easy procedure, but just set aside about 90 - 120 minutes to complete it. The only tools you need are (1) a refrigerator, and (2) a hair dryer. :-)

73, Jim / W6JHB


On   Wednesday, Mar 26, 2014, at  Wednesday, 5:59 AM, Jack Chomley wrote:

> Tonight I have been experimenting on PSK31 at 3 watts and 5 watts. In my shack the OSC Temp is about 38 deg and transmitting my CQ call about every 60 seconds @ 3 watts takes the OSC Temp to 39 deg, on RX it drops back to 38 deg.
> At 5 watts it goes up to 41 deg, but immediately settles back to 38 deg.
> My question is, what would the estimated frequency change be, per degree of OSC Temp change? I am trying to work out the total freq shift between the start and the end of my PSK31 transmission.
> Now, I have not done the OSC temp compensation routine to my radio. Trying not to go down this road in case I make a hash of it :-)
> In closing, I will not be using WSPR or JT65 etc with this radio.
>
>
> 73,
>
> Jack VK4JRC
>
> Club.    www.cqara.org.au
> Member WIA SARL ARRL
> GQRP       #14392
> QRPARCI #15068
> VKQRP.    #833
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

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Re: KX3 OSC Temp And Freq Drift Relationship?

vk2rq
In reply to this post by Jack Chomley
Just back up your configuration with the KX3 utility before you start, and for extra security write down your current refcal value. If you do somehow "make a hash" of the compensation procedure, you can simply restore your saved configuration to get back where you started. Even if you somehow didn't save your configuration, it is very simple to simply revert the compensation menu setting from "CUSTOM" back to "STANDARD", and zero-beat your radio to the WWV carrier to reset your refcal.

Of course, you should only do what you are comfortable with, but in my view (I finally got around to doing the procedure last weekend) it is a reasonably straightforward and nicely automated procedure that yields a big benefit for digital mode operation. The Elecraft team has done well with this one.

73,
Matt VK2RQ

> On 26 Mar 2014, at 11:59 pm, Jack Chomley <[hidden email]> wrote:
>
> Tonight I have been experimenting on PSK31 at 3 watts and 5 watts. In my shack the OSC Temp is about 38 deg and transmitting my CQ call about every 60 seconds @ 3 watts takes the OSC Temp to 39 deg, on RX it drops back to 38 deg.
> At 5 watts it goes up to 41 deg, but immediately settles back to 38 deg.
> My question is, what would the estimated frequency change be, per degree of OSC Temp change? I am trying to work out the total freq shift between the start and the end of my PSK31 transmission.
> Now, I have not done the OSC temp compensation routine to my radio. Trying not to go down this road in case I make a hash of it :-)
> In closing, I will not be using WSPR or JT65 etc with this radio.
>
>
> 73,
>
> Jack VK4JRC
>
> Club.    www.cqara.org.au
> Member WIA SARL ARRL
> GQRP       #14392
> QRPARCI #15068
> VKQRP.    #833
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
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Re: KX3 OSC Temp And Freq Drift Relationship?

Jack Chomley
Thanks everyone for the ideas.....I have the XG50 for the job. Doing the Temp Comp routine hopefully will improve the reliability of decoding PSK31 directly with the KX3 and my HCT. Yes, will write down REFCAL, save config thanks Matt.

73,

Jack VK4JRC

Club.    www.cqara.org.au
Member WIA SARL ARRL
GQRP       #14392
QRPARCI #15068
VKQRP.    #833

> On 27 Mar 2014, at 6:51 am, Matt VK2RQ <[hidden email]> wrote:
>
> Just back up your configuration with the KX3 utility before you start, and for extra security write down your current refcal value. If you do somehow "make a hash" of the compensation procedure, you can simply restore your saved configuration to get back where you started. Even if you somehow didn't save your configuration, it is very simple to simply revert the compensation menu setting from "CUSTOM" back to "STANDARD", and zero-beat your radio to the WWV carrier to reset your refcal.
>
> Of course, you should only do what you are comfortable with, but in my view (I finally got around to doing the procedure last weekend) it is a reasonably straightforward and nicely automated procedure that yields a big benefit for digital mode operation. The Elecraft team has done well with this one.
>
> 73,
> Matt VK2RQ
>
>> On 26 Mar 2014, at 11:59 pm, Jack Chomley <[hidden email]> wrote:
>>
>> Tonight I have been experimenting on PSK31 at 3 watts and 5 watts. In my shack the OSC Temp is about 38 deg and transmitting my CQ call about every 60 seconds @ 3 watts takes the OSC Temp to 39 deg, on RX it drops back to 38 deg.
>> At 5 watts it goes up to 41 deg, but immediately settles back to 38 deg.
>> My question is, what would the estimated frequency change be, per degree of OSC Temp change? I am trying to work out the total freq shift between the start and the end of my PSK31 transmission.
>> Now, I have not done the OSC temp compensation routine to my radio. Trying not to go down this road in case I make a hash of it :-)
>> In closing, I will not be using WSPR or JT65 etc with this radio.
>>
>>
>> 73,
>>
>> Jack VK4JRC
>>
>> Club.    www.cqara.org.au
>> Member WIA SARL ARRL
>> GQRP       #14392
>> QRPARCI #15068
>> VKQRP.    #833
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
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Re: KX3 OSC Temp And Freq Drift Relationship?

KE6BB
In reply to this post by Jack Chomley
RE:  The extended temp compensation is mostly about transmit frequency stability. It might make some difference in decoding PSK31 as the rig cools down, but I would expect that to be a smaller effect.

To elaborate a bit more on wunder's comment, it is about frequency stability as related to temperature changes.  The reason it appears to affect transmit more than receive is because the KX3 power amplifier transistors generate lots of heat during transmit, heating up the SI570 oscillator.  The SI570 also generates heat, but generates the same amount of heat during transmit and receive (it doesn't know the difference), so it tends to add to the heat during transmit, and slow the cool-down during receive.  The relatively poor heat rejection capability of the KX3's enclosure (designed for TFR, not heat rejection) figures into that mix as well.  So, fast frequency drift during transmit, slower drift during receive.

I've used SI570's for a number of years on my SDR projects, but have always had the luxury of being able to isolate them from the radio's final amplifier transistors, and any other heat source.  They have therefore been very frequency stable once their temperature levels off following power-up.  The tight packaging of the KX3 doesn't allow that.  From the reports so far, it looks like Elecraft's "look-up table" approach is pretty effective at compensating.

Mark
KE6BB
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