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eHam Forums => Boat Anchors => Topic started by: AB1MN on May 05, 2013, 11:25:03 AM



Title: IS THIS THE VERY FIRST NCX-3?
Post by: AB1MN on May 05, 2013, 11:25:03 AM
At the May of 2013 New England Amateur Radio festival (NEARFest), I picked up a rather dusty National NCX-3 transceiver. There were a couple of unusual things that caught my eye about this particular radio and got me wondering about its history. Unfortunately, I was not able to get a history when I purchased the radio, so I still have some detective work to do although the ham that sold it to me said that the rig used to belong to an engineer at that worked at National.

As I started cleaning the radio and looking it over, I noticed a number of unusual things that got me wondering about the history of this rig:

1.   The front panel showed no evidence of ever having been screen printed with the labeling of the various controls. This was not a case of the lettering having worn off, it never was there.
2.   Likewise, the NCX-3 identification had never been incorporated into the bezel surrounding the frequency dial.
3.   There is no “National” labeling or logo on the bottom of the front panel as there are on production models.
4.   On the rear of the front panel, an area has been machined out to clear the circular frequency dial.
5.   The circular frequency dial does not look like a production item. It consists of a translucent plastic disk with a printed thin plastic overlay having the frequency markings (this appears to have been glued on to the translucent plastic, but is now starting to separate).
6.   There is no serial number printed on the rear of the chassis.
7.   In fact there was no labeling at all of any of the rear panel controls or connectors, other than some hand labeling to identify the controls.
8.   The antenna jack is a BNC connector and not the SO-239 that appears on production models. This was not a case of a BNC connector being retrofitted in place of the SO-239 as the hole sizes are significantly different.
9.   There is no printing on the chassis to identify the various tube types as there is on production models.
10.   Several of the holes for tubes have been elongated or enlarged in order to reposition the tubes slightly.
11.   There are several areas on the chassis with layout lines used for locating the holes for various screws and components. Clearly, these would not have been present on a production unit.
12.   The Transmit/Receive relay is mounted in a socket. My understanding is that the relay on the NCX-3 was originally soldered in and then in a later production run mounted in a socket to facilitate replacement.
13.   The MIC Preamp and Relay Control tube is a 6AN8 in this radio and a 6GH8 in production models. (I still need to verify that the socket is wired for the 6AN8 and that this is not just a case of the wrong tube in the socket.)

So, if you can provide any insight or history into this radio it would be greatly appreciated.

Thanks,
Bob  AB1MN


Title: RE: IS THIS THE VERY FIRST NCX-3?
Post by: W4OP on May 05, 2013, 05:28:23 PM
Run it by KM1H, he worked for National during that time period.

Dale W4OP


Title: RE: IS THIS THE VERY FIRST NCX-3?
Post by: KD0REQ on May 06, 2013, 02:29:45 PM
sure sounds like an engineering prototype