[Jeffhs]

Congrats on getting that radio working -- it's a good feeling getting these old sets singing again as they did when they were new (as I have done with several 1950s-'60s vintage Zenith radios). I was having a difficult time finding the tuning knob on your Grebe set until I did a Bing search and found info on the Grebe Synchrophase sets, model MU-1 et al. It was there I found a picture of a Grebe set similar to yours. The tuning knob is a large gear-shaped affair directly beneath the tuning dial. It then dawned on me why I didn't see this knob (or the tuning dial) on your radio--the picture I was looking at was of the empty cabinet; you must have had the chassis on the bench at the time.

BTW, your Grebe radio should do very well for DXing, if you use an outdoor antenna. I noticed a hole for a "local-distance" switch on the bezel, so this radio must have been built for distance reception. It has a TRF circuit (a console set of the same brand I saw on the same website yours was on has the same circuit design, according to the description), which, as I understand it, could work very well in areas far away from local radio stations, but it didn't work nearly as well in urban areas with several powerful stations. My grandmother had a late-1940s vintage GE clock radio with a TRF circuit (only four tubes). She used it mainly in her summer cottage, which was located between Cleveland and Akron, Ohio; while the radio worked well receiving all local stations from both areas, one 50kW Cleveland station, the transmitter for which was just about five miles down the road, came in not only on its fundamental frequency (1220 kHz), but also around 600-650 kHz at the low end of the dial. (I have the same difficulty with a 1kW local station about two miles away from me that comes in on 1460 and 560 kHz, at least during the day; the problem seems to disappear when they cut their power in half after dark.) I don't know if you are particularly close to any flamethrowers like that, but if you are, you could have the same problem with your set. If your radio has an RF amplifier stage ahead of the antenna, as I think it does, images shouldn't be an issue unless you are almost literally within spitting distance of one or more very strong stations. It was mentioned by, I believe, wa2ise in answer to another post that AM RF amplifiers in most post-war radios did little more than improve the set's image rejection, not RF sensitivity.