Here's how we will get the DSP-610 ready for the off-board power amplifier (OBPA). if you already have a DSP-610 built and working (like I do) you are going to have to do some dis-assembly to get ready for the OBPA. The schematic for the DSP-610 main board with the unnecessary components removed is the files section below. If you are building the DSP-610 main board from scratch, use the schematic below as a guide for which parts to use.
Basically the MPSH10 post-mixer amplifier is gone. The output of the filter-switch matrix is fed directly into the SKY65017 MMIC amplifier. So we'll need to jumper from the R84 side of C132 over to the R81 side of C129. Q10 is no longer the driver, it's now the pre-driver and is tweaked to produce a little more gain (20 dB or so) and there's no impedance conversion so the drain sees 50 ohms from the next stage. This means that the maximum output will be:
Po = Vcc^2/(2*Zo) = 13^2/100 or around 1.5 watts
which is more than we need to drive the driver satage in the new PA.
We also need to remove RL1 through RL4, which will be a relief to everyone who can't find them anyway. The new PA board has a RX output for 10M and another for 6M and these can be connected vie coax jumpers to pins 7 and 8 of RL1 and RL4 as shown in the schematic. R103 and R104 are good places to pick up control signals for the new PA and the PA_BIAS signal can be use both for biasing the new PA and activating the T/R relay.
The only other signal we need is a switched 13.8V for the relays which we can get from anywhere convenient.
I'm going to start taking mine apart this weekend and I'll take pictures as I do.