Been listening around on the shortwave bands this last week as I work from home in the office. I was using a Hallicrafters S-40A that I had recently recapped until I noticed that every day the log scale was having fits and changing. One day Radio havana Cuba would be around 65.5 on the scale, the next day it was around 50. That is quite a change even with drifting during warm up. it appears that the dial is a little loose, so i will have to take the front off the radio and realign and tighten it back up.
The other thing I noticed that when the Hallicrafters S-40a was first turned on it would pop and snap for about 30 to 60 seconds, even with the volume and rf gain turned all the way down. It would make an awful racket when you applied power to it. I notice that the only electrolitic cap in it was C46 but the schematics do not show the polarity, so it could be wrong.
The Hallicrafters is still a graet radio with a fantastic sound for a 65 year old radio.
I switched out the Hallicrafters S-40a yesterday for the Hammarlund HQ-150. The HQ-150 is a fantaastic radio even with it's bassy sound. It receives as well as my kenwood TS-850 on the shortwave bands. The dial is fairly accurate and I can usually get pretty close to the frequency I want to use using the dial. The only thing wrong with the HQ-150 is the Null and Peak filter is boogered up right now. It still works great for shortwave listening but not so great for CW (Morse Code) work. The probelm with the Null and Peak filtering is a couple of bad capacitors, mainly C87 and C88. They were bad when I got the radio and decided to dig into it and fix the problem with the help of a local ham tech that really knows these old tube radios inside and out. It is just a matter of finding the right caps to put back in. The values are Silver mica 3300 mmf %5 and Silver Mica 1100 mmf %2. It originally had the little flat square type that had a color code in it.