National NC183 NR

[KA7WOC]

Any NC 183 NR owners?  (Rack mounted diversity version.)  I have a couple of questions regarding terminal strips on the back of the chassis.  Antenna and Audio out are clear enough but I also have a two terminal strip and a four terminal strip.  A description of their proper use is desired.
tnx

[The Slab Bacon]

I have never seen one of those, but do have a 183 and a 183D.

My guess would be that the 2 terminal strip is probably for muting, and the 4 terminal strip is probably the way you tie the AGC (AVC) lines together. Most receivers used in diversity mode have their AGC tied together to equalize the gain and output volume for both receivers.

Are you sure it is a diversity version?? If so that would be my bet.


                                          The Slab Bacon

[KA7WOC]

For reference see:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=380247347427

Mine looks very similar to this one.
tnx for your comments.
Bob

[The Slab Bacon]

that is a neat receiver! The AVC output is an RCA connector, the IF output is also a pretty cool amenity as well. It has 2 additional control knobs as well, the ones next to the tuning knobs. It would definately be kool to have a pair of them.

The terminal strips are speaker and antenna for the 2 smaller ones. the 4 terminal one, the first 2 terminals must be the muting (note they are jumped together in the pix) the second pair on the 4-termaial board are the only mystery left. A little careful examination and tracing should reveal their function. that thing looks way different from a standard 183.

have you looked on BAMA yet??

Where is W3JN?? He is the one that should know!!

[KM1H]

Thats an interesting radio. It appears to have the same added 3rd IF stage with variable selectivity as in the NBS-1 variant which JN and I own. In that case it is an excellent AM battle conditions radio with superb audio.

Carl

[k4kyv]

How is all the weight of that rack-mounted receiver supported by just the front panel, without any side brackets?

[KA7WOC]

My guess is, not very well. 
My rig came in an SP600 cabinet and honestly I cannot say if it is different from the one posted on ebay.  I'm planning on pulling it out of the cabinet and giving it some stare time and testing tonight. 
It is not R390A or SP 600 heavy but brackets would be advised.  Fortunately I have several to choose from and use if needed.
Bob

[KM1H]

National hung most of their rack mounts that way, you dont just bull it up to the rack and slap some screws in. The intelligent (required) way in commercial or military installations was a pair of L angles for the radio to slide in on. The racks were built with internal vertical supports drilled and tapped for the rails.

Carl

[KA7WOC]

Got into the rig after work.  There are full panel height brackets running full depth of the chassis panel support  Found some 'modifications' underneath and discovered one of the terminal strips has been added.  After replacing the missing voltage regulator and  the filter caps, the rig plays well.  Push-pull audio.  Will take a little longer to get it 'rackworthy'. 
The extra knobs are for local or external osc and IF selection.  The mode switch is is in the upper left position.
Still have not found a schematic for this variation.
bob

[w3jn]

I've never had one; seen plenty at hamfests but they were always a bit out of my price range.

Not seeing what those terminal strips are marked I couldn't give you much guidance on how to use 'em.

[KA7WOC]

The antenna terminal strip has been re-wired as the send/receive remote switching.  The speaker terminal strip is intact.   A new two terminal strip was added for the antenna and the IF out (SO 239) was rewired as an alternative antenna connection.  I believe the 4 terminal strip might have originally been wired to function similar to the Collins for muting etc. but can't say for sure.  Haven't traced it out.