1. if you see the amp schematic related to farhan's Minima. You find these
"band select" used there for LPF switching with help of a decoder.
2. "TRIFILAR" It is a way of making uniform the winding transformer..
three insulated wires, are twisted at 5 turns per inch. then such combined
wire is wound , number of turns on the toroid core.
then the start and finish of each winding is identified and soldered to
3. YES> You can connect a headset there.
4. A there are three such across the lower filter. they are used as series
LC resonators. I remember Farhan had described them.
B. there are two more for the final setting of BFO (LSB) and BFO (USB)
5. Yes. It is for Antenna INPUT /OUTPUT.
6. The schematic clearly shows that they are driven by transistors and the
coils are shown connected to 12V. Thus, obviously they are 12V relays.
7. It helps keeping the source pins of both FETs at a slightly positive
voltage( means to keep gates relatively at negative potential wrt to
The actual voltage could be adjusted for optimum performance of the mixer.
Hope i have tried to clear your doubts or made further complication, LoL
all the best
On Tue, Apr 4, 2017 at 4:46 PM, Glenn Gutshall <dmarc-noreply@xxxxxxxxxxxxx>
Looking at the schematic diagram at http://www.phonestack.com/
These questions arose:
1. What is the component marked "Band Select"?
2. Define "Triflar" - is this wrapping three conductors as if they were
one or 3 separate sets of 8 wraps?
3. Between Q17 & Q18 is a jack. Is that the audio out?
4. There are several 22p variable capacitors. How are they set?
5. I take it the circular symbol above D1 is the RF out jack is that
6. There are several relays (I count 3 SPDT & 1 DPDT) what is the coil
voltage on these? 5V? What about contact ratings?
7. How is the pot to the right of the LM7805 set? Also there are +5V
connections noted elsewhere in the schematic. Are they supplied by this