[Elecraft] XV-144 Receiver RF Amp Bias Adjustments

[Don Wilhelm]

David,

Well, most all XV transverters out there have this problem and operate 
without obvious symptoms.  The situation is that there is no diode 
across the K5 coil to absorb the "kickback" voltage from the relay coil 
inductance when the power to it is removed.  If you find the time 
between transmit and receive slowed, then that change will help the 
situation. Actually, there is a path  present through the contacts of 
K4, so the diode is still doing its job as long as K4 remains closed 
(and it normally will).  It is just better to have the diode connected 
directly across the K5 relay coil.

All I am saying is that if you get a chance to remove the bottom cover 
for any reason, that is a good time to make the modification - if there 
is no reason to remove the bottom panel, then leave it as-is for now.

73,
Don W3FPR

On 7/30/2011 7:31 PM, KJ4YQK wrote:
> I replaced Q2 and now I have the voltage on R16, and I am able to change the
> Receiver RF Ap bia.  Starting it off at 179 mV.  I am able to get it above
> 200 with no problems.  One transister off, at least I have two good
> transisters nwo.
>
> Updating the Schematic now for the IF and Control circuits.
>
>   I plan on getting this up on the air tonight, maybe in time for the local 2
> meter net.
>
> Thanks for helping me out, this really gave me a good look at the circuits.
> I will write some notes on it.
>
> I will look at the correction you mentions abt the circuit board.  What
> effect does that have on the operation of the unit if left as is?
>
> David
>