ADE1 mixer kit Diplexer


ken WA2MZE
 

Any suggestions on the Diplexer coils and capacitors for use at 45mhz?  Application will be in a scratch built ubitx.


 

At higher freqs (VHF) it's recommended to use a Q of 3 or 4 or 5

Using a Q of 4 L1 as T37-17 with 21 turns is 200 ohms needing about 18pF capacitance

L2 should be about 12 ohms using a T37-0 with 9 turns and a capacitance of about 300 pF

I would parallel a trimmer across C4  to tune the parallel circuit easier.

If you order a kit (when avail) I'll make sure you'll get any custom parts (replacements)

Again...use https://toroids.info to calculate the values for any freq and part

Anybody need help with toroids.info???

-Diz

On 1/21/21 10:44 AM, ken WA2MZE wrote:
Any suggestions on the Diplexer coils and capacitors for use at 45mhz?  Application will be in a scratch built ubitx.


ken WA2MZE
 
Edited

I have some SBL-1s in the junkbox.  These have separate ground connections for the RF and LO inputs, as well as separate connections for the cold end of each of the 4 coils of the transformer secondaries.  I can therefore feed an unbalancing bias voltage into the LO side transformer for CW operation, and use a diplexer on the IF output connection.  These mixers work from 0.5 to 400mhz.  I will use one for the first mixer feeding the 45mhz IF on a manhattan style (or pad cut) home brew board.
I also have some RMS-5 mixers that could be used for the 45mhz to 11 mhz conversion.  I don't know if these are the same pinout as the ADE-1, if so I could order a PCB from you.

Found some T37-10's from a recent order, the required inductance for L1 would require 17 turns, and the material is suitable for 45mhz.  Guess I can use those, also have some 25pf trimmer caps in junk box.
Have T37-0's for L2, the 300pf cap could be a 50pf trimmer and a 270pf SM in parallel.  If the trimmer won't peak, I'd have to figure out if I'm too high or too low and then go to the next available value for the fixed cap.
The uBitx has a 45 mhz LPF on the IF output of the first mixer to knock down a second harmonic spur of the 45 mhz signal on TX.  I think the duplexer will serve that function, so the LPF wouldn't be needed (the ubitx has no duplexers on their mixers).