|
RFS1 Loss
Built this kit, and the PA1, years ago and I thought it worked okay, but I never really checked it thoroughly.
I used a DPDT switch to take the amp in and out of the circuit, so I routed the coax through the switch, using RG-174 as suggested in the instructions.
So, I just got this stuff out of storage and was checking it out and was seeing a loss of about 2-3dB and started to investigate.
I realized that I had been dumb and that the loss was most likely because of the stupid wiring job I did, so I fixed that and wired the power through the switch like I should have originally.
Satisfied that it would work properly now that I had removed a foot or so of lossy coax wired through a standard DPDT switch, I tested it but found that the loss was still there.
I put 7W into the RFS1, I get about 3.5-4W out.
Okay, maybe I didn't do such a great job when I built it, so I open it back up and touch up all the solder joints and check for shorts, but I still get the same thing, 7W in, 3.5-4W out.
So now I'm at a loss.
The coax is (I believe) Radio Shack RG-174, which I know isn't the highest quality, but six inches or so shouldn't cause that much loss.
I've checked the power and SWR on both the input and output side and get the 7 in, 4 out, with SWR of 1.2 or lower, so SWR loss or radio protection isn't the culprit either.
Other than the loss, it seems to work fine. When it's powered, it does switch in the amp, and it amplifies, but I don't get as much output as the specs say; 7W in, 25-28W out, but I'm not sure where the loss is. Some is probably my original wiring of the PA1 not being optimal, but if the amp is only getting say 4W in because of loss before the relay, then that looks better, being 6-7dB or so gain, but maybe there is more loss on the output side of the RFS1 so I'm not really seeing the true output.
Anyone have any ideas?
|
