At what input level?
Both sig-gens give the same results, a little better than a 20 DB sig + noise to noise ratio.
Steve,
The notes are out in the shack. Several years ago, on the R-390 e-mail reflector (
http://mailman.qth.net/pipermail/r-390/), I asked how did the military do it? Roger Ruszkowski, one of the more knowledgeable that post there did several write-ups. He worked on these in the military and taught the classes.
So the short version with out the notes, the best as I remember. Disconnect the speaker and hang a 600 ohm resistor on those terminals. Connect a volt meter across the resistor; get the calculator ready if the meter does not have a db scale. Crank up the sig-gen till the volt meter reads a certain (x) value; write down that value. Turn on the modulation, think it was 400Hz at 30%; write down the value........................do the math. DB= 20 times the log of V2 divided by V1. Do this on all the bands, if you get that 20DB number with just about the same output from the sig-gen, the receiver is gud to go. If not, you have more work to do.
My thoughts are to treat the RF section according the impedance of the antenna. So if I'm going to feed the RF section apples, then peak all 6 octaves, (18 RF coils) for apples. I use the same antenna for TX & RX. Tunna keeps the TX happy with 50 ohms unbalanced.
Using the balanced antenna input puts the signal through "all" the IF stages. The unbalanced doesn't, if my memory serves me this evening. More plus reasons to go though the balanced than the unbalanced antenna connection. But I doubt many TX antennas present a 125 ohm balanced load to our transmitters, nor would they like it. So I peak the RF section; balanced antenna connection one side grounded, 50 ohm coax, from the 50 ohm connection on the sig-gens.
Anyway, I could be all wet behind the ears and really don't care much. The plastic radios (YeaComWoods) seldom read less than a S9 RFI level, the R-390/A's any where between 20-40 DB on the carrier meter. I can't hear piss weak stations anyhow.
Craig,