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PBSK31

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Bruce Rattray

PBSK31

What is the safe level to operate the K2 at for the PBSK31 mode? I'm
thinking 2 or 3 watts. tnx 73 Bruce ve5rc

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Don Wilhelm

Re: PBSK31

Bruce,

I always operated mine at 5 watts. The K2/10 has a large heatsink area.
You may want to try even higher than 5 watts - if you want to check to make
sure it is OK, feel the bottom rear panel of the K2 enclosure. It will
be warm,
But you should still be able to hold your fingers on it. If it is too
hot to
touch continually, it is too hot.

73,
Don W3FPR

On 4/24/2016 12:37 AM, Bruce Rattray wrote:
> What is the safe level to operate the K2 at for the PBSK31 mode? I'm
> thinking 2 or 3 watts. tnx 73 Bruce ve5rc
>

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lstavenhagen

Re: PBSK31

In reply to this post by Bruce Rattray

I agree with Don, the K2 should be brick-on-key at 5 watts at least. On m 12V batteries, mine are almost that way at full power, the heat sink at the bottom definitely gets warm but seems to go forever without getting hot.

On a regulated PS, though, that doesn't drop into the 11v range like my batts, that may not be true....

73,
LS
W5QD

vk2rq

Re: PBSK31

Wouldn't want to go much higher than 5W though -- you want to maintain linearity, and PSK31 has a peak-to-average-power-ratio of 3dB.
73, Matt VK2RQ

Envoyé d’Outlook Mobile

On Sun, Apr 24, 2016 at 6:18 AM -0700, "lstavenhagen" <[hidden email]> wrote:

I agree with Don, the K2 should be brick-on-key at 5 watts at least. On m 12V
batteries, mine are almost that way at full power, the heat sink at the
bottom definitely gets warm but seems to go forever without getting hot.

On a regulated PS, though, that doesn't drop into the 11v range like my
batts, that may not be true....

73,
LS
W5QD

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David Giles-3

Re: PBSK31

In reply to this post by Bruce Rattray

I've made hundreds of contacts using JT65 and JT9 with my K2 at 5W.
Most of these portable on a 12v battery with solar charging. With a 48
second transmit period, it's probably more of a stress test than BPSK31.

73 de David VK5DG / VK3TUN

On 24/04/2016 2:07 PM, Bruce Rattray wrote:

> What is the safe level to operate the K2 at for the PBSK31 mode? I'm
> thinking 2 or 3 watts. tnx 73 Bruce ve5rc
>
> ______________________________________________________________
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Phil Wheeler-2

Re: PBSK31

David,

Do you do anything special to ensure frequency
stability in those modes with your K2?

Phil W7OX

On 4/24/16 3:02 PM, David Giles wrote:

> I've made hundreds of contacts using JT65 and
> JT9 with my K2 at 5W. Most of these portable on
> a 12v battery with solar charging. With a 48
> second transmit period, it's probably more of a
> stress test than BPSK31.
>
> 73 de David VK5DG / VK3TUN
>
> On 24/04/2016 2:07 PM, Bruce Rattray wrote:
>> What is the safe level to operate the K2 at for
>> the PBSK31 mode? I'm
>> thinking 2 or 3 watts. tnx 73 Bruce ve5rc

Don Wilhelm

Re: PBSK31

Phil,

I cannot say if David did anything special for frequency stability, but
any K2 above SN 3000 had the BFO stability mod and the PLL Temperature
compensation mod installed which can achieve the necessary stability.
K2s below SN 3000 can be upgraded with those upgrade kits.

The stock PLL Temperature Stability Mod has resistor RA as a 33k
resistor. That resistor value can be modified to achieve closer
temperature stability for any particular K2. The K2 manual does not
contain information about how to vary and check the compensation, but
that information is contained in the instructions for the PLL
Temperature Stability Mod - download from Elecraft.

The temperature change in the K2/10 is not likely to be very much even
for long periods of transmit because the PA transistors and heatsink are
not close to the VFO/PLL and BFO areas and there is a lot of 'air space'
inside the enclosure.
With the KPA100 added, that air space is much more confined and the heat
from the KPA100 PA transistors will have an influence.
In other words, while the stock K2/10 may be sufficiently stable, the
K2/100 may need some 'tweaking' of the RA resistor value for equivalent
stability.

73,
Don W3FPR

On 4/24/2016 6:23 PM, Phil Wheeler wrote:

Phil Wheeler-2

Re: PBSK31

I've done all those mods to #380, Don. I didn't
realize they were that effective! And after
reading of thermal stability issues some have had
in JT65 (e.g., using a KX3) I assumed the K2/10
would have even larger issues in those modes,
given the age of the design.

Your message is good news indeed!

73, Phil W7OX

On 4/24/16 3:52 PM, Don Wilhelm wrote:

> Phil,
>
> I cannot say if David did anything special for
> frequency stability, but any K2 above SN 3000
> had the BFO stability mod and the PLL
> Temperature compensation mod installed which can
> achieve the necessary stability. K2s below SN
> 3000 can be upgraded with those upgrade kits.
>
> The stock PLL Temperature Stability Mod has
> resistor RA as a 33k resistor. That resistor
> value can be modified to achieve closer
> temperature stability for any particular K2.
> The K2 manual does not contain information about
> how to vary and check the compensation, but that
> information is contained in the instructions for
> the PLL Temperature Stability Mod - download
> from Elecraft.
>
> The temperature change in the K2/10 is not
> likely to be very much even for long periods of
> transmit because the PA transistors and heatsink
> are not close to the VFO/PLL and BFO areas and
> there is a lot of 'air space' inside the enclosure.
> With the KPA100 added, that air space is much
> more confined and the heat from the KPA100 PA
> transistors will have an influence.
> In other words, while the stock K2/10 may be
> sufficiently stable, the K2/100 may need some
> 'tweaking' of the RA resistor value for
> equivalent stability.
>
> 73,
> Don W3FPR
>
> On 4/24/2016 6:23 PM, Phil Wheeler wrote:
>> David,
>>
>> Do you do anything special to ensure frequency
>> stability in those modes with your K2?
>>
>> Phil W7OX
>>
>> On 4/24/16 3:02 PM, David Giles wrote:
>>> I've made hundreds of contacts using JT65 and
>>> JT9 with my K2 at 5W. Most of these portable
>>> on a 12v battery with solar charging. With a
>>> 48 second transmit period, it's probably more
>>> of a stress test than BPSK31.
>>>
>>> 73 de David VK5DG / VK3TUN
>
>

Don Wilhelm

Re: PBSK31

Phil and all,

Yes, those mods can do a lot for temperature stability of the K2. Adjust
the Thermistor board RA value if necessary to achieve the best stability.
The KX3 can achieve good temperature stability if the Extended
Temperature Compensation procedure is completed - I would not attempt
any of the JT data modes without doing that first.

73,
Don W3FPR

On 4/24/2016 7:28 PM, Phil Wheeler wrote:
> I've done all those mods to #380, Don. I didn't realize they were that
> effective! And after reading of thermal stability issues some have
> had in JT65 (e.g., using a KX3) I assumed the K2/10 would have even
> larger issues in those modes, given the age of the design.
>
> Your message is good news indeed!
>
> 73, Phil W7OX
>

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David Giles-3

Re: PBSK31

In reply to this post by Phil Wheeler-2

Hello Phil,

My K2's serial number is in the 5000s so it has the temperature
stability circuit built in. I have only just recently started using it
on JT9 after some time on JT65. I don't start transmitting until it has
warmed up after 5 minutes or so. I first used it outdoors at my remote
site (see VK3TUN on qrz.com) and had to shield it from the wind. Now
that the shed is up, that is no longer an issue. I don't know if it
helps that much with dissipating the heat, but I always have the bail
extended.

73 de David VK5DG / VK3TUN

On 25/04/2016 7:53 AM, Phil Wheeler wrote:

> David,
>
> Do you do anything special to ensure frequency stability in those
> modes with your K2?
>
> Phil W7OX
>
> On 4/24/16 3:02 PM, David Giles wrote:
>> I've made hundreds of contacts using JT65 and JT9 with my K2 at 5W.
>> Most of these portable on a 12v battery with solar charging. With a
>> 48 second transmit period, it's probably more of a stress test than
>> BPSK31.
>>
>> 73 de David VK5DG / VK3TUN
>>
>> On 24/04/2016 2:07 PM, Bruce Rattray wrote:
>>> What is the safe level to operate the K2 at for the PBSK31 mode? I'm
>>> thinking 2 or 3 watts. tnx 73 Bruce ve5rc
>
> ______________________________________________________________
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>