R-390A/URR Radio Receiver


If you're here looking for R390A schematics, then you probably already know about the R390A Y2K manual. The Y2K manual, already in its second release, is primarily developed from the '85 Navlex manual. This endeavor was undertaken by several dedicated 390a enthusiasts: Al Tirevold, Barry Hauser, and me. I volunteered redrawing the schematics and sketches into a hopefully, more easily read format using standard-size paper. The originals were done using Visio and converted into the manual's PDF format that you download to save a lot of file space. Well, file compression is functional, you do get the information but it distorts the drawings a little. What I have here are the originals, updated and presented in their original Visio format. If you have Visio they will download into good-looking drawings where circles are round, junction dots are clearly visible, and text stays readable in its intended fonts and doesn't run over into adjacent lines. If you don't have Visio, you can download a free viewer from Microsoft (see below for link). They will open in your browser window where you can view and print them. They are here as self-extracting zipped files to save space. Just double click on them after downloading to extract the original .vsd file. I also have them available in a .PDF format.

I measured the DC current levels on the various B+ lines going to the different modules using an HP428B Clip-on DC Milliammeter. These values were added to Fig. 5-11 (Power Distribution Diagram) from the Y2K manual. This new diagram is called Power Distribution Current Levels and is included as an additional troubleshooting aid. Note: My R390A has silicon diodes instead of the 26Z5W rectifiers but does not have the compensating dropping resistor as recommended by EIB895. This results in a slightly higher B+ voltage which may slightly affect the current levels shown.

Borrowing legalese from Barry as he so eloquently states on his site: No warranty is expressed or implied regarding merchantability (prohibited anyway) or fitness for any particular use. These drawings are provided as a courtesy without monetary consideration for information purposes only and no liability for any aspect of possible application is assumed by the provider, distributors, developers or compilers, web hosts, or anyone else for that matter. Safety in the use, maintenance and repair of the equipment described requires proper knowledge, training, equipment and adherance to critical procedures all of which are the sole responsibility of the recipient/reader. By opening and reading and/or downloading these document files, you affirm your agreement with this disclaimer and further agree to refrain from distributing these documents in whole or in part in any form to others without express permission to do so.

The R-390A in the picture above is a beautifully restored Rick Mish unit donated to the Battleship Missouri Amateur Radio Club by Mike Taylor. Click on the picture and you can see Rick's impeccable attention to detail. If only mine would look that good!

You can download the Y2K manual from Barry's site here.

Or you can download it from Al Tirevold's site under his 'REFERENCES' here.

Download Visio Viewer from Microsoft here

Feel free to let me know of any errors you come across or tips on how the schematics could be improved. You can e-mail me: just click here.

Here are my current offerings. The easiest way to download is to right-click on the 'DOWNLOAD' and save to a file. But it also works if you just click on 'DOWNLOAD' normally.