[Elecraft] Power too high in PSK31 / SSB

[Rob May]

Ok, Joe, that's the way I understand it and is the way I'm doing it.  I adjust mic gain with Digipan in "tune" mode until it's right at the level where the first bar starts to flash.    Compression is set at 0.  Output power is set with the Pwr knob.  I generally run between 5 and 20 watts on PSK.  I get good reports and make plenty of contacts, so I must be doing something right.  
Rob
NV5E

> From: lists at microham-usa.com
> To: roblitespeed at hotmail.com; elecraft at mailman.qth.net
> Subject: RE: [Elecraft] Power too high in PSK31 / SSB
> Date: Sat, 4 Oct 2008 12:18:46 -0400
>
>
>
>> So, no bars equals more noise and IMD or even one bar causes
>> more IMD?
>
> My information comes directly from Lyle - I don't remember if
> it was on the reflector or in a direct e-mail during testing
> of some beta ALC code.
>
>> FWIW, I leave my K3's power control set at 100 watts, but I
>> adjust the mic gain control to a setting which ensures I get
>> zero ALC reading (even one bar causes a noticeable increase
>> in IMD as measured on a PSKmeter)."
>
> Setting the power out to 100 watts in PSK will guarantee that
> the final is being driven into compression on peaks if you see
> ALC (enough drive to reach 100 watts).
>
> I measure no difference in IMD with no ALC (just below the
> point at which the first bar shows) vs. five solid bars if
> the power level is kept below about 60 watts. Put another
> way, if the peak (CW equivalent) power level is kept below
> about 60 watts to prevent compression (and the onset of IMD
> generation) in the K3's finals, there is no difference with
> ALC just below the level of the first bar and five solid bars.
> If the mic/line gain is open just enough to get power output
> the PSK has more noise, has about 1 dB more IMD, and power
> output is less stable than with five bars of ALC.
>
> What Rich's procedure does accomplish is assure that the power
> output does not exceed the 50/60 watt level.
>
> 73,
>
> ... Joe, W4TV
>
>
>
>> -----Original Message-----
>> From: elecraft-bounces at mailman.qth.net
>> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Rob May
>> Sent: Saturday, October 04, 2008 11:03 AM
>> To: elecraft at mailman.qth.net
>> Subject: RE: [Elecraft] Power too high in PSK31 / SSB
>>
>>
>>
>> Joe, W4TV, wrote:
>>
>>
>> Running "no bars" of ALC in PSK/AFSK causes the microphone
>> gain to be increased to compensate for the insufficient
>> drive. This will result in added distortion (noise and IMD)."
>>
>>
>>
>> Richard, VE3JAY, wrote:
>>
>>
>> FWIW, I leave my K3's power control set at 100 watts, but I
>> adjust the mic gain control to a setting which ensures I get
>> zero ALC reading (even one bar causes a noticeable increase
>> in IMD as measured on a PSKmeter)."
>>
>>
>>
>> So, no bars equals more noise and IMD or even one bar causes
>> more IMD?
>> These two statements seem to contradict each other. I'm
>> thinking that the
>> ALC will only limit mic gain, it won't bring it up if it's
>> low, other wise you wouldn't
>> have any dynamic range on your voice, the ALC would tend to
>> make everything the same level. I'll just keep doing the way
>> I've been doing it. I get good
>> reports and the power output that I expect.
>> Rob
>> NV5E
>>
>>
>>
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