National HRO 500 Communications Receiver Video #1 - Power Up Testing

This radio is not working and it may be due to something defective in the internal power supply. I can bypass the internal power supply with an external 12V supply and bring the radio to life, maybe.

[@cindys1819]

This was the Absolute SUPER professional grade General coverage receiver of the mid 1960's. This was like $1200. in the mid 60's dollars and a lot elite users were clients from embassies to ultra luxury yachts. The VLF bands, to maintain good sensitivity. had a seperate preselector/amp. It WAS somewhat complex in terms of block function structure. One of th e greatest receivers I ever owned...including, Collins and Racal units. My uncle later has the HRO 600.

[@Slay3rOne]

Oh I also got my hands on this same model a year or two ago, it was quite cheap I'd say, not working of course. It's been sitting there for a while, as I have other things to take care of for the moment, but I definitely intend on attempting to repair it one day. Curious to see how this goes! Good luck with the repair!

[@decastroesilva]

1° Like, muito bom dia!!! É sempre muito prazeroso acompanhar as restaurações dessas 'máquinas', que registram os fatos do tempo por mãos habilidosas, competentes que trazem a vida e preserva a história do Rádio e sua eletrônica, parabéns Jim's.

[@myradiovideos]

I have 3 of these radios, and they all need to be repaired, your videos will be interesting..

[@w6by]

This radio mutes the audio when the synthesizer is unlocked. Internally is a harmonic generator and a phase detector similar to an FM discriminator that locks when the proper harmonic is selected. That circuit is a bit finicky to adjust, but is the most common cause of unlock conditions, and probably a lot of components have drifted over time. National did not use the best quality components in this radio.

[@truthreigns7]

good interesting video

[@cindys1819]

Why don't you order the mfg service manual instead of making it hard on yourself?