Another small item out of yeterday's haul. A Lowe HF-225 general coverage receiver. Not quite TEA but they have their uses for some diagnostics. This was described as faulty. When I asked they thought it was deaf. An obviously one owner from new item in good clean condition with all the paperwork. It also has the optional FM and syncronous AM detector. The manual indicated a sensitivity of around 1uV / -107dBm. Fired up the R&S CRTU/CMU-200 and connected it up.
Hmm -35dBm, 60dB dwn at 1MHz, yep thats deaf . It was bit better at higher frequencies but not much.
It was on frequency and all filters and the attenuator work as expected. So to basics. It has to antenna inputs a 50R SO-239 and 200R balanced (via 4:1 BALUN). There is also an option (not fitted) for a internal pre-amp for a whip antenna on the SO-239. The antenna in use is selected by a 3 position slide switch on the rer panel. So going to check on the 200R input, as soon as I touched the switch the signal came up. It's a PCB mount 90 degree switch. Not easy to change or find a quality one to fit. So I appled a little switch cleaner and all is good .Sensitivity as actually a it better than spec.
The HF-225 is a late 80's design that was produced until 1997. It was mostly Plessy SL series IC's designed for military radios. It wasn't cheap at around £500 (US$850) but had good performance, holding it's own against receivers costing twice as much. They are still sought after. It's small and neat enough to sit on a bedside table or similar.