Elecraft › [K2]

K2 - Protect those Finals

Classic

List

Threaded

4 messages Options

John Huggins, kx4o

K2 - Protect those Finals

K2 Folks,

After monitoring this list for quite a while and knowing a few locals
who use or used the K2, the topic of damaged finals comes up often.

I especially took note of a post highlighting the KAT2 has a "real"
power meter which, I suppose, augments the stock power output control
loop... right?

This brings up a simple question.

If I order the K2, is ordering and installing the KAT2 a smart move that
will reduce the chance of damaging the finals?

Thanks.

John, kx4o
______________________________________________________________
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

k6dgw

Re: K2 - Protect those Finals

On 4/21/2012 9:44 AM, John wrote:

> After monitoring this list for quite a while and knowing a few locals
> who use or used the K2, the topic of damaged finals comes up often.

It does? I hadn't noticed that, the K2 is very good at protecting
itself, but since it concerns you ...

> If I order the K2, is ordering and installing the KAT2 a smart move that
> will reduce the chance of damaging the finals?

The KAT2 will match a very wide range of impedances presented to the
antenna connector and it fits inside the K2. It is well worth the
investment, especially if you intend to use your K2 in portable
situations with less than well matched antennas. I use mine primarily
that way, often on SOTA summits, with a variety of antennas. As to
protecting the PA transistors, I suppose it could, I just don't think
that's the reason you want it.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2012 Cal QSO Party 6-7 Oct 2012
- www.cqp.org

______________________________________________________________
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

Dave-7

Re: K2 - Protect those Finals

In reply to this post by John Huggins, kx4o

Protecting the finals in a K2? Comes up often on this list? I don't
recall that. Maybe you are thinking of another list or maybe you could
copy some of these discussions for as a refresher for those of us who
don't recall?

I've been reading this list for 10 years or so. I think a discussion
of the finals has came up a couple of times. Those were usually where
someone installed them incorrectly. Left out thermal pads or failed to
retighten the screws after a few hours of operation. Follow the
instructions and you'll be very unlikely to have any problems with the
finals in a K2, or K1, or KPA100.

73 de dave
ab9ca/4

On 4/21/12 11:44 AM, John wrote:

> K2 Folks,
>
> After monitoring this list for quite a while and knowing a few locals
> who use or used the K2, the topic of damaged finals comes up often.
>
> I especially took note of a post highlighting the KAT2 has a "real"
> power meter which, I suppose, augments the stock power output control
> loop... right?
>
> This brings up a simple question.
>
> If I order the K2, is ordering and installing the KAT2 a smart move that
> will reduce the chance of damaging the finals?
>
> Thanks.
>
> John, kx4o
> ______________________________________________________________
> 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
>

______________________________________________________________
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

Don Wilhelm-4

Re: K2 - Protect those Finals

There is one situation with the basic K2 (no KAT2, no KPA100, no KAT100)
when the PA transistors can be stressed. That is if you are running in
the upper range of the power control and you have an antenna that
presents a low impedance.

Giving a complete explanation -- the RF detector in the basic K2 is a
simple diode detector. When driving a lower impedance load, that
detector output voltage will be lower than that from a 50 ohm (or higher
impedance) load. With that reduced voltage, the MCU *thinks* the power
output is lower than it actually is, and will increase the drive to make
up for that fact. If the conditions are extreme enough, you can drive
the PA transistors to their maximum.

There is a protective mechanism in the CAL CUR menu setting - if that
current limit is reached, the K2 will reduce power. I would recommend
you do not increase CAL CUR above 2.50 amps unless either the KAT2 or
KPA100 or KAT100 is added - then you can increase CAL CUR to 3.50 amps.

The other thing is to not run the K2 with "all knobs to the right"
There is little difference on the receiving end between 10 and 12 (even
15 watts is only 1.76 dB greater than 10). Keep the power to a
reasonable level and all will be OK.

Most K2 PA failures are due to abuse of one nature or another.

73,
Don W3FPR

On 4/21/2012 1:44 PM, dave wrote:

> Protecting the finals in a K2? Comes up often on this list? I don't
> recall that. Maybe you are thinking of another list or maybe you could
> copy some of these discussions for as a refresher for those of us who
> don't recall?
>
> I've been reading this list for 10 years or so. I think a discussion
> of the finals has came up a couple of times. Those were usually where
> someone installed them incorrectly. Left out thermal pads or failed to
> retighten the screws after a few hours of operation. Follow the
> instructions and you'll be very unlikely to have any problems with the
> finals in a K2, or K1, or KPA100.
>
>
> 73 de dave
> ab9ca/4
>
>
>
>
>
> On 4/21/12 11:44 AM, John wrote:
>> K2 Folks,
>>
>> After monitoring this list for quite a while and knowing a few locals
>> who use or used the K2, the topic of damaged finals comes up often.
>>
>> I especially took note of a post highlighting the KAT2 has a "real"
>> power meter which, I suppose, augments the stock power output control
>> loop... right?
>>
>> This brings up a simple question.
>>
>> If I order the K2, is ordering and installing the KAT2 a smart move that
>> will reduce the chance of damaging the finals?
>>
>> Thanks.
>>
>> John, kx4o
>> ______________________________________________________________
>> 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
>>
> ______________________________________________________________
> 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
>