[Elecraft] KX3 IQ Outputs - What to expect?

[Peter Lambert]

Hello again John,

Looking at the schematic, any difference you see should be so slight that
you'd not make comment on it.  If it were me I'd take a look at the
inductors LD-LG (on page 4 of the schematic) to see if there is the
possibility of one of them being shorted.  I haven't had look at these but
it's common to twist the terminating wires together - a likely spot for a
short.

I'd stick the CRO on the output of each of the 4 inductors (where the
circuit shows "RX_I" and "RX_Q" and the opposite side of C1K and C1L) all
the levels here should be pretty much identical.

Of course you can only expect this over the range of +- 96kHz or so.

73's Peter VK4JD

PS - love this little radio, it's an amazing bit of portable kit

-----Original Message-----
From: John [mailto:kx4o at hamradio.me] 
Sent: Tuesday, 17 March 2015 1:53 PM
To: Peter Lambert; Elecraft at mailman.qth.net
Subject: Re: [Elecraft] KX3 IQ Outputs - What to expect?

Thanks Peter.

I do see the 90 degree phase difference and how it changes if I move above
or below the test frequency.  However the amplitude of just one, the ring
conductor on the connector, decreases with increasing delta frequency.  The
amplitude of the tip remains steady regardless of the delta frequency.

I assume this isn't what I should be seeing.  Now I need to figure out me
next move as this seems to not be what the PX3 wants.

Does anyone know a reason the I and Q might be different amplitudes for the
same signal?

Thanks.
John, kx4o

On 3/16/2015 8:38 PM, Peter Lambert wrote:
> Hi John,
>
> In this situation the amplitude of both the I and Q channels should be 
> the same and they should always be 90 degrees out of phase.
>
> Peter VK4JD
>
>