[R-390] Mackay 3007A

[Tom Chirhart]

The only safe way to use these receivers is with an isolation transformer. I have a Triad N-68X that I plan on using but have way too many other projects ahead of this one. I guess we should take this off the 390 reflector now and keep it between us. Thanks for the bandwidth. 73
Tom K4NCG an old Chief Radioman who still swears by the 390's not at them like the R-1051's...

Sent from my iPad

On Feb 20, 2011, at 6:37 PM, N4TUA <n4tua at aol.com> wrote:

> 
> 
> 
> THANK YOU Al; W8UT, Tom; K4NCG and Don for the help.
> I am beginning to think this is a rare receiver or at least the manuals are rare. This receiver is running now but will need some more work. I replaced all (4) plug in capacitors (note R-390A similarity), one cooked and vented/blew the fuse. This receiver is a transformer-less receiver and makes B+ from the 120 volt line. I am working from hand drawn schematics parts and pieces which I have started developing as I troubleshoot. I am not sure but it looks like the 120 volt input needs to float from ground. In other words it may need an isolation transformer or run it with out a ground wire connected. It looks like the B+ is centered at chassis ground like +45 volts to ground and -45 volts to ground = 90 volts B+. As you can tell I have much more to do, sure wish I had a schematic...
> 
> Best 73, Collin
> 
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