Where are the places that most benefit from shielded connectors linking components?
From Jerry Gaffke in post
#26552
I'm getting by without coax, using the wiring harnesses provided, but I did cut them reasonably short. ? On critical signals I twisted the signal wire with the associated ground wire, perhaps 1 or 2 turns per inch. ?Caps (signal to ground) on both ends of the tuning pot cable are a good idea. ?My antenna cable is about 2" long, I wouldn't want to go much longer without using coax. ?If you use coax, I'd ground the braid on both ends in all cases, the center conductor carries the signal. ?Something like RG178 coax is small and flexible enough. ?Should be able to extract pins from the connectors provided by pressing the springy metal tab at the wire end of the the rectangular window while gently tugging at the wire. ?Then you can solder RG178 directly to those connector pins.
I think a conservatively designed commercial rig might use coax for all of the signals below to avoid potential trouble. ?I'm listing them roughly in the order in which I'd consider them critical, opinions will vary. ?
? ? Main board DDS connector to Raduino
? ? Main board to tuning pot middle pin (and 0.1uF caps on both ends)
? ? Main board to antenna connector
? ? Main board to microphone
? ? Main board to volume control center pin
? ? Main board to volume control top pin
Larry Smith?WA9DOH? adds in post
#26579?
Shielded wire from the DDS to the VFO input on the main PCB
Shielded wire from the tune pot to the DDS
RG174 from the PCB ant. to the SO239 or BNC (rg8X)
When running the power wires run them down low on the Metal chassis...you can tape them down.
I hope to shield if not encase the DDS from ?the main PCB.
I may add 1000uf with parallel 100 pF to the 12v power connector pin to ground.
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