[Milsurplus] [ARC5] Interesting ARC-3

[Mike Morrow]

There was the 8-channel R-77()/ARC-3, the 16-channel R-428()/ARC-36, and the 48-channel R-608()/ARC-49.  Now this.

This appears to be a commercial or other-country aftermarket modification of an original R-77//ARC-3 (without the never-issued guard receiver IF input connector of R-77A and later).  It obviously has three banks of eight crystals arranged under the metal blank cover, and the photo of the receiver with the top removed shows the added shelf with the three crystal bank select relays.  The crystals are much smaller than the original CR-1A/A, likely similar to the CR-18/U used in the 48-channel R-608/ARC-49.  Three crystals would be associated with each LO harmonic select dial, just as there were two crystals in the R-428 and six crystals in the R-608.

The crystal select control box looks more commercial-service than military, yet the entire modification is way beyond ham hack quality.

It's too bad that there are no photos of a nomenclature plate that might indicate the source of the modification.

Interesting variation, Dave.  Thanks for posting, and including the link and enough info to make going there worthwhile.

If the AN/ARC-3 had a guard channel, and been built in one box, it would have been the perfect WWII command set.  It's a very innovative true auto-tune system.

Mike / KK5F

-----Original Message-----
>From: David Stinson <arc5 at ix.netcom.com>
>Sent: Nov 26, 2017 8:36 AM
>
>This is an interesting ARC-3 variant. 
>24 channels, but where do the crystals go?
>The original 8-channel sockets are blocked
>with a plate.  Are the crystals in the control
>box?
>
>https://www.ebay.com/itm/292343727195
>
>73 OM DE Dave AB5S