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Title: Yet another Valiant Question: VFO Post by: ka4koe on March 25, 2013, 07:52:48 AM The VFO on the Beast is way outta wack. The output freek on 80m is about 150 KHz above the dial reading, so I have to dial in around 3730 to get 3885. I understand there is a calibration procedure in the manual. Is this amount of error correctable via the adjusting trimmers, and is this also a normal condition given the age of the transmitter?
I also noticed quite a lot of VFO backlash. This may just be loose hardware on the connecting shaft. The red TRANSMIT lamp is out. This is likely an easy replacement. AHHHHH, the joys of YET another project, and the R388 isn't even finished yet. Yep, I've got it bad, really bad indeed. Philip Title: Re: Yet another Valiant Question: VFO Post by: WQ9E on March 25, 2013, 09:04:20 AM Start by making sure that the dropping resistor for the VFO has been replaced with a higher wattage but same value part. The VFO does stabilize more quickly when the replacement resistor is mounted back inside the VFO compartment as was done originally.
If the VFO doesn't move smoothly you need to clean and re-lubricate the ball reduction drive in the VFO. Pull it, clean the old lube out completely ( I flush it with WD-40) and then repack with standard bearing lube. Be careful not to lose the bearings (3 in the sides, depending upon the style the thrust bearing will either be a separate ball or machined as part of the shaft, I have seen both in Johnson gear). Tighten the case halves just enough so that there isn't slippage under normal torque loads. Now make sure that the VFO dial pointer has equal overlap at either end of the dial and that the capacitor is at full mesh at the low frequency end. Once all of this is done you are ready to recalibrate. Title: Re: Yet another Valiant Question: VFO Post by: KM1H on March 25, 2013, 11:15:03 AM A NOS 6AH6 will improve stability over the 6AU6 used.
Carl Title: Re: Yet another Valiant Question: VFO Post by: ke7trp on March 25, 2013, 10:13:15 PM Before adjusting the slugs on the top of the VFO, Check the VFO voltage and or replace the regulator and tube. It might come back in line. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
Another tip.. When you take the valiant out of the case, Set the radio on its side and work on it from that angle. Do not set the valiant on its back. If you do, The front panel will flex out and the VFO coupling will snap off. If that happens, you really have alot of work ahead of you... C |