Farhan, thanks a lot for the schematics and great for the minimal hardware upgrade you suggest. Can we use through hole components or SMD are mandatory? Can inductances also be made in through hole discrete components too? I am asking this as the local store where I usually get the components has a very limited supply of SMD components and no toroids, while they have a full set of through hole components.
Il 12/nov/2018 09:01, "Ashhar Farhan" <
farhanbox@...> ha scritto:
i have further simplified the fixes:
1. change the resistors R26 and R46 to 220 ohms (from 470 ohms). this increases the darlington pair's standing current and decreases the Harmonic distortions.
2. the 90 MHz trap was difficult to tune unless you had a spectrum analyzer. Instead, we can use a Low Pass Filter instead. A 'T', rather than a Pi was used. This helps better in isolation or RX/TX path.?
3. The LPF consists of an L-C-L of 300nh, 47pf, 300nh.?
4. With the relays that are now used for ubitx,? the harmonics at 3.5, 7 and 10 are in under -45 dbc. we don't need the axicom relays.
I am attaching a hand-drawn circuit to explain this better.
- f
