GRC-109 12V DC PS Prototype As with any “One Of” designs, many compromises were made to utilize parts and space available.
Now, some systems test and then off to The Bush for a shakedown cruise. The former stand-alone receiver power module is now installed inside to power both the GRC-9 and GRC-109 receivers. The GRC-109 connectors are made from PVC 3/4 inch threaded pipe adapters with stock Molex female pins held in place with hot glue. It draws about 800 ma with just the receiver section turned on, about 4.8 amps with both sections turned on and the transmitter “key down”. Load and Line regulation is good, with 12.6 VDC input although it is a linear circuit except for the receiver filament source. Need to review the component grounding scheme. The transmitter supply is also quiet in the receiver above 5 MC or so, but some switching harmonics can be weakly heard in the receiver down on 80 meters with the TX supply running. The receiver power supply is electrically very quiet. I couldn’t quickly come up with a simpler, more efficient method for powering them without the heat loss. The only significant heat source is the wire wound dropping resistor for the 6.3 volt DC (despite the 6.3 VAC error on the below schematic) transmitter filaments. Just powering the GRC-109 the supply runs barely warm to the touch. (If I can find a female chassis connector for one!). The connector is very rugged, water tight and should be good for several kilovolts insulation-wise.Ībove: Design and fabrication complete, testing underway, it’s On the Air, it works great! I included a small fan for forced-air cooling which I might need if I include a GRC-9 transmitter power supply inside in the future. The leads penetrate the cap and cover through a small access hole. The solidified glue holds the 4 sockets firmly in place and the pipe cap is attached to the PS cover with a #8 machine screw. I then filled the connector with “hot glue” from a glue gun, squirting the molten glue inside via two access holes in the pipe cap. I positioned the females inside the pipe cap using the receiver male plug as an exact alignment positioner. These are made for 0.125 inch OD pins, the exact size as the ‘109 receiver power pins.
Note: The R/S catalog mis-identifies these sockets as 0.093 inches – they are actually 0.125 inches!). I made the female connector from a 1/2 inch white PVC pipe end-cap for a housing and used 4 “molex” – type female sockets from Radio Shack connectors (R/S Part Number 274-154. So I built up a prototype connector and attached it to the power supply so the ‘109 receiver could plug into it directly, just like the BA-48. The 4-pin battery connector in the GRC-9 and GRC-109 receive systems are unique to those radio as far as I can tell. (The GRC-9 prototype power supply was designed to be powered primarily by a 12 Volt vehicle battery so design simplifications were made at the expense of efficiency.) I later decided to add a capability to allow it to power the GRC-109 receiver as well, but as usual, a custom connector was needed. It uses a custom – designed ferrite core transformer with separate secondaries for each voltage and it draws about 500 ma during receive. It works great and is very quiet, running at approximately 20 KHz, no mechanical, acoustic or electrical noise is evident. The first GRC-9 prototype supply (gold box) provided power to a 4-contact female cable plug (gray cable, seen above) that mated with the receiver battery connector of the GRC-9 Transmitter-Receiver. GRC-109 Receiver powered by DC-DC Converter – N6CC
0 kommentar(er)
