I picked up a cosmic blue National at a hamfest. Thought at first glance it was another NC-270 but it turned out to be the NC-155. I read Osterman's descriptions. Specs for the cheaper NC-155 shows it as slightly more sensitive. Both are 6 to 80 meter ham bands only. The NC-270 has a calibrator built in and the NC-155 lists a calibrator as optional accessory. Other than that one item, what are the differences between the two?

Tnx,

-- Rich

The manuals are here

http://bama.edebris.com/manuals/national/

Carl

Yes, have the manual copies. Looked up the National ad in the 1962 handbook. Looks like the NC-155 is essentially a somewhat reduced NC-270 at $80 cheaper. No notch filter and fewer selectivity levels. Also looks like Osterman may have gotten the specs on sensitivity wrong. He lists the NC-270 at <1.5 uV and the NC-155 at <1.0 uV. (I suppose since the < is in front, he is theoretically correct)
National shows both specs at the same sensitivity, 1.0 uV. Will see if I can locate one or two of the reviews which are listed in Osterman. Here is a copy of the ad writeup.


Tnx,

-- Rich

Since the front ends are the same, even most of the parts are shared, so is the sensitivity. Ive never read Ostermans book or most other "collectors" types as they all get too many things wrong.

Carl

Yes, I've caught several errors in his book, but it is a decent overall reference. I will note this error when I write up the radio for my website.

We all make mistakes. Even one of the the prior owners of the NC-155 who replaced the receive/ send switch with a DPST made a rather serious mistake. Dead set. It would have worked OK if he had not mixed up the connections. Yes, B+ on the back terminal strip. I wonder if a shocking experience was why it was sold.

Hey, the hamfest price was right. I will replace the switch with a DPDT since the original design was to turn ON a device connected to the terminal strip when switched over to send. (And that terminal strip device must never see B+)

Tnx,
Rich