I just bought an excellent example on ebay for $300 from a fellow Ham Radio hobbyist. The last time I used an HP339A was back in 1980, when working proudly in Test Engineering at Harris Broadcast Products in Quincy IL.
Very much want to use it to check out my vintage Phase Linear 700B rebuild, as well as Pioneer and B&O receivers from the 70's! It even has an AM BCB range AM detector, which was undoubtedly used for Broadcast Transmitter monitoring. With a custom mixer, I am sure that the Ham 160, 80 & 40m AM frequencies could be monitored.