Custom Double Balanced Diode Ring Mixer Kit


ken WA2MZE
 

Suggestion:  lift the ground connection from the center tap secondary of T1 from ground (connect to ground via a PC jumper that can be cut and provide a pad to connect to the center tap).  This will allow injecting a voltage into the mixer to unbalance it to pass the LO signal out the RF/IF ports.  This will allow the use of the Diplexor with this option.  That way, one can use the mixer in the uBitX circuit.  They unbalance the mixer to allow the LO signal to get out of the mixer when transmitting in CW. (the mixers run balaterally).  I don't think you can do this with the ADE-1 mixer, I don't know if separate pins are used for the input primary and secondary grounds (I think they are on the older metal can through hole style cased MCL mixers).  You can't use the diplexor in the IF output to inject the unbalace bias, the 51 ohm resistors get in the way, though maybe a large value RF choke with a low DC resistance in series with the mixer IF output to supply the bias, and capacitor coupling to the diplexor / IF signal output would work.  Either option would require cuts and jumpers to the PCB.


 


On 3/4/21 11:36 AM, ken WA2MZE wrote:
Suggestion:  lift the ground connection from the center tap secondary of T1 from ground (connect to ground via a PC jumper that can be cut and provide a pad to connect to the center tap).  This will allow injecting a voltage into the mixer to unbalance it to pass the LO signal out the RF/IF ports. 

Like this?


You can also take a drill bit and manually remove teh GND connection on the bottom of the PCB


This will allow the use of the Diplexor with this option.  That way, one can use the mixer in the uBitX circuit.  They unbalance the mixer to allow the LO signal to get out of the mixer when transmitting in CW. (the mixers run balaterally).  I don't think you can do this with the ADE-1 mixer, I don't know if separate pins are used for the input primary and secondary grounds (I think they are on the older metal can through hole style cased MCL mixers).  You can't use the diplexor in the IF output to inject the unbalace bias, the 51 ohm resistors get in the way, though maybe a large value RF choke with a low DC resistance in series with the mixer IF output to supply the bias, and capacitor coupling to the diplexor / IF signal output would work.  Either option would require cuts and jumpers to the PCB.


ken WA2MZE
 

What did you do there, put a diplexer on both center taps?  Not exactly what I meant.  I just wanted to be able to feed a bias voltage into the diode ring.  The uBitx doesn't have a diplexer, so they feed a dc bias through two isolation resistors in series bypassed in the middle  (1K and 2.2k) into the IF output of the mixer  and AC couple the IF signal in/out of it.  The Diplexer would put a DC short to ground through a 51 ohm resister, so I figured I could feed the DC bias into the primary ct, through an isolation resistor or choke, and AC bypass that center tap to ground with a 100nf cap.  You seem to have divided the diplexer into two to allow for 2 IF signal outputs, not exactly what I meant!  Without moding the PCB, I would just lift the CT lead of the primary and connect a through hole 100nf cap to the ground via and the transformer CT lead, then bring out the transformer ct lead off board through a 3.3K ohm resistor for the bias, and leave the IF output the way it is. (Diplexer tuned to 45mhz in this case).


 

I was just showing you what I have in the works...nothing more

Use a drill bit to remove the GND

-Diz

On 3/4/21 1:40 PM, ken WA2MZE wrote:
What did you do there, put a diplexer on both center taps?  Not exactly what I meant.  I just wanted to be able to feed a bias voltage into the diode ring.  The uBitx doesn't have a diplexer, so they feed a dc bias through two isolation resistors in series bypassed in the middle  (1K and 2.2k) into the IF output of the mixer  and AC couple the IF signal in/out of it.  The Diplexer would put a DC short to ground through a 51 ohm resister, so I figured I could feed the DC bias into the primary ct, through an isolation resistor or choke, and AC bypass that center tap to ground with a 100nf cap.  You seem to have divided the diplexer into two to allow for 2 IF signal outputs, not exactly what I meant!  Without moding the PCB, I would just lift the CT lead of the primary and connect a through hole 100nf cap to the ground via and the transformer CT lead, then bring out the transformer ct lead off board through a 3.3K ohm resistor for the bias, and leave the IF output the way it is. (Diplexer tuned to 45mhz in this case).


ken WA2MZE
 

OK on that.   What does your possible mod actually do?


 


On 3/4/21 4:16 PM, ken WA2MZE wrote:
OK on that.   What does your possible mod actually do?

Not sure...it's just a "differential" double balance diode ring mixer...no ground connections.

May work very well or not at all...but it is balanced...or maybe organic?...whatever  :)

I have 10 PCBs I ordered but have not built/tested one.

I can include one free with any future parts order (goes for anyone else interested

-Diz