Hmmm, maybe a synchronous detector? I feel a project coming on. On the function switch, there is an ACC or accessory position to add a proper FM detector. You tune off to the side and use slope detection in the broad position, just the way the old buzzards did. The NC303 in the broad position works great on the top end of 10 meters to listen to the FM activity there. Some have reported 9 to 10 MHz signals on 20 meters I have a fix for that later in the article. These are the only spurious responses I noted while testing this radio. Note that it is possible to have foreign broadcast images from around 24.5 MC on 10 meters. As a bonus, the NC-303 low IF can be aligned much easier than an HQ-170, unless it has been the victim of major tampering. Each S unit is about 6 dB, and the scale above S9 is pretty close, until you get to full scale. The S meter even works correctly! I measured it when I had the equipment set up on the bench to do an HQ-170. The AGC time constant is a little short by today's standards, but you can add a larger capacitor if you want. There is a product detector (that works) for linear detection of SSB. It can be operated without AGC in the CW position or with AGC in the SSB position in the narrow 400 cycle, or a wider bandwidth as desired. The CW can be operated in a narrow selectivity or a wider one. (OK, it is not an R390 with a 16 KHz filter, but we are comparing similar cost brackets here. For AM it has an 8 KHz wide bandwidth position (presumably compatible with its VHF converters) which sounds beautiful when tuned to a Class E rig. It has excellent sensitivity on all bands and superior selectivity. It is dual conversion with the first IF at 2215 KC and the second at 80 KC. The dial calibration accuracy and length of the dial itself is better than its contemporaries. It uses high stability ceramic coil forms for the oscillator, not cheap paper forms like those used in the HQ-170. Unlike many of the cheaper National receivers, which delivered a lot of performance for the price, this one is heavily braced and has a very rigid thick front panel for good mechanical stability. Projects/Receivers/HammarlundHQ170-180.html. I discuss the comparison of thes three classic receivers at length in my article on the HQ-170: I would also rate it at better than the Hallicrafters SX101. I would prefer the NC-303 to the HQ-170, in spite of my love for Hammarlund receivers. The National NC-303 is a real performer for its time.
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