[Elecraft] [K2] How much AF volts at 1kHz to get full RF power using KSB2?

[Don Wilhelm]

Gareth,

During transmit you should have about 1.4 volts DC on pin 1 or the 
balanced modulator U5.
I just measured the U5 pin 1 audio using a 'scope with a 10X probe and 
found the peak to peak voltage ranged from 200 to 400 millivolts.  If 
you have a good microphone, you should see a similar amplitude signal.  
The RF output at U5 pin 4 should have a similar amplitude.
The BFO injection at U5 pin 6 should be greater than 200 millivolts peak 
to peak and on the one I just measured there was a 1 volt BFO signal there.

73,
Don W3FPR

On 9/29/2014 4:52 AM, Gareth - M5KVK wrote:
> I have K2 serial no 03885. I've recently finished building the KSB2 SSB
> adapter, but I'm having problems getting it to work.
>
> The problem is very low output power when I speak into the mic. I'm using
> an Icom MK36 mic and I've set the P1 header as per the KSB2 manual;
> including the resistor to get Mic bias.
>
> The options as set SSBA = 2, SSBC = 2-1 and I've done the carrier balance.
>
>
>
> I've checked all the DC voltages and they are OK. I used a scope on U5
> (NE602) and there is an enormous disparity between the voltages on pin 6
> (hi) and on pin 1 (very low). The waveform on U3 pin 7 (the compressed AF
> out) is greater than that on pin 4, (the AF input), but not by much.
>
> I want to eliminate the Mic as the source of the problem (It works
> perfectly with the IC-756 Pro II) by using an AF sig gen, but I'm not sure
> how much AF drive should cause 100% output power.
>
> Gareth - M5KVK
>