Hi All, I am in the process of restoring one of those R-4B radios that were offered on this list. I have never owned an R-4B and I have a couple of questions:
First of all, I have the receiver 95% operational. 1) I am used to the S meter on other radios going to full scale when RF gain is reduced to zero. The R4b doesn't do that. Also, the RF gain control just reduces background noise level by about 5 S units while the signal remains about the same. Is this normal? 2)I think the previous owner made some changes in the AVC circuitry. As it stands now AVC fast seems to operate as it would in any other radio, a fairly fast tracking rate. AVC slow, however, is really slow taking a full 4-5 seconds for the S meter reading to decay in the absence of a signal. Is this normal? I will be examining the AVC circuitry for mods tomorrow but won't dive into that if this is normal operation. AVC off works as normal. 3) Last question: With RF gain fully CW on the R4B the ambient (no signal) noise level is 3-4 S units above where the TS-850 and TS-480 indicate the noise level is for the same antenna system (trap dipole up 27') and RF gain full on. Is this an indication that tube radios have a higher sensitivity to atmospheric noise? With the RF gain fully CCW the indicated noise level on the R4B is comparable to the newer radios with RF gain full on. Not sure what to make of this. Thanks! Ron KK7KZ _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
