G4NSJ - National HRO 5TA1 5A1 comms receiver - part three 

Enjoying this series here, Ray. To answer your question, I've restored some US domestic sets from the 1930s. The term 1st detector was used quite commonly for a valve working solely as the mixer (with a separate valve as oscillator) as 1st detector/Osc, where valves like the 6A8 combined both functions. It is a strange term to we Brits! Looking forward to more of the story. 73

Fascinating Ray. Please keep the updates coming. From ZS land

Hi Ray, sorry I gave you such a challenge, but it sounds like you are enjoying fixing it. I’m also very pleased that you are making progress. I have no idea what the previous history is for the radio, but my son-in-law and I went to look at a vehicle that he was interested in buying. Next to it was a very beat up old van, inside were two old valve radios and this is one of them. When I expressed an interest in it, the owner told me to take it, otherwise it was going to the local council tip. All the best, Roy - G4WTV

Thank you for sharing Ray , it's all marvellous as always .73

Hi Ray, Yank here. I've been fixing all sorts of radios since 1966, and I've not heard of 1st Det/2nd Det. I have always called your 1st Det "The Mixer", also, and in some cases it's a mixer/oscillator (1R5 for instance). Perhaps it's just a National term, as they were a bit weird. Cheers, mate. Oh, I had a look at all my pots and the 10Ks I have are all screwdriver adjust carbon track units. Sorry.

Thanks for the journey. Keep it up!

Pleased to hear I'm not the only one with NAFFI Gongs !

Hi Ray Having just refurbished / "updated" a 1960s Codar CR45 regen receiver (two valves + rectifier) with great success, I think I'll quit while I'm ahead and leave complicated stuff like this HRO to experts like you!

i hope these two youtube videos help a bit

very nice work! its very frusterating haveing to find that someone dinked up the radio! like to just smack them around lol!

Hi Ray. I wonder if "1st detector" is an RF wideband sample used for noise blanking. Just a thought. PS. The camera didn't pick up the wet shirt spot until you mentioned it. Better to have egg on ones shirt, than on the face. 73 M8

Ray, when convirting from 6V to 12V heaters, would the H.T. need to be changed too, so to suit that for the 12V valves.

the audio amp should be a 6v6

ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-l0yYBoiaLa0.html