[Elecraft] K3 pwr out on digimodes

[AD6XY]

Thanks for this table. It appears we should be aiming for 2-3 bars not 6!

Ideally, everyone will have an accurate RF power meter in circuit. 

If you know the PA current, which you can read accurately and the voltage
which can also be read, you can calculate your input power. All you then
need to know is the power required for 25W output on your band(s) of choice.

This assumes a good match which is safe as no K3 user would operate into a
poor match, but many power meters will not give accurate readings at high
VSWR either. For example with Bird Thrulines you need to do a calculation to
find the true forward power if there is significant reflected power. Meters
like the LP100 do read true forward power, but can still lose accuracy if
the VSWR is high.

< irrelevant nostalgia>

When I started out I bought an FT290, an antenna and a VSWR meter. Back then
in the UK it was a license requirement to know what your transmitted power
was relative to the 100W limit, or failing that your input power and to be
able to demonstrate to an inspector that you were within limits. Our limits
were 100W carrier power, considered to be 100W of CW/FM and 400W PEP for
AM/SSB. Non-coders were only allowed above 144MHz, previously 430MHz, and
the VHF/UHF activity was maybe 10 times what it is now.

</ irrelevant nostalgia>


hb9ari wrote:
> 
> Benson,
> 
> I've done some measurements some time ago with my K3 #1212 and i had the 
> following values:
> K3 power set to 20W, f=7.040MHz   25W 50 Ohms dummy load 
> MCE/Weinschel    LP-100A Wattmeter
> mode USB   1 kHz sine audio at rear line-input, level adjusted to have 
> the desired ALC bar configuration
> 
> ALC bar(s)           Mesured [W] (avg)
> 0                             8.16
> 1 blinking                  9.4
> 1steady+1blk         15.95
> 2steady+1blk         20.72
> 3steady+1blk         21.2
> 
> These values correspond to the above mentioned set-up (K3 #1212 uP rev 
> 2.78) and displayed on the LP-100A with RF head #1143
> 
> 73 QRO fr Rudolf, HB9ARI
> 
> 
> Benson wrote:
>> I do not have the benefit of an external wattmeter at the moment and 
>> frequently use digital modes, esp. JT65A. Assuming I want to transmit 
>> 25 W or less, if I have PWR set at 25 and adjust the mic gain for ALC 
>> just under 1 bar (basically just until one bar disappears), 
>> approximately how much power would be  transmitted? The resolution of 
>> the 100W rf scale doesn't really help at low levels.
>> ------------------------------------------------------------------------
>>
>> _______________________________________________
>> Elecraft mailing list
>> Post to: Elecraft at mailman.qth.net
>> You must be a subscriber to post to the list.
>> Subscriber Info (Addr. Change, sub, unsub etc.):
>>  http://mailman.qth.net/mailman/listinfo/elecraft    
>>
>> Help: http://mailman.qth.net/subscribers.htm
>> Elecraft web page: http://www.elecraft.com
> _______________________________________________
> Elecraft mailing list
> Post to: Elecraft at mailman.qth.net
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft    
> 
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
> 
> 

-- 
View this message in context: http://n2.nabble.com/K3-pwr-out-on-digimodes-tp2163956p2167000.html
Sent from the Elecraft mailing list archive at Nabble.com.