Mohawk selectivity

Tom,

You could broaden the response by changing the values of the resistors and capacitors used in the switching network which control coupling and "Q" in the final IF section; the existing values will give you a starting point for broadening the response curve. Or I guess you could use a coupling cap between transformer sections to broaden the response.

HOWEVER, properly tuned the Mohawk (like its close cousins in the Halli line) is designed to receive AM one sideband at a time so properly tuned the current setup provides response equivalent to a "traditional" setup with a 10 Khz. IF bandpass. When properly tuned the carrier is placed near one cutoff slope in the IF bandpass and the audio response extends out to near 5 Khz. at the 6 db down point (in the broadest selectivity setting).

Make sure the 50 Khz. IF is properly aligned in the Mohawk, it is a critical alignment and must be done at a fairly low signal level to avoid incorrect alignment. Then make sure that the BFO is also calibrated properly. To tune in an AM signal do so in the SSB mode with the BFO set for "0" and zero beat the AM signal. Then choose AM mode and the sideband with the least interference. The nice thing about these selectable sideband receivers is the ability to switch sidebands quickly when QRM rolls in; it is the one thing I really miss after pairing up an SX-88 with my Desk KW in place of the SX-101 and SX-115 which resided there earlier. The SX-88 allows the same effect but requires retuning to do so.

The IF gain control generally should be run fairly low on the Mohawk, particularly on the lower bands. Hallicrafters, Drake, and others wisely put the basic gain set control inside the chassis where it was to be adjusted during alignment. The IF gain control on the Mohawk is the equivalent of this control and the temptation is to run it wide open which leads to high internal noise level and distortion. Typically you should run the RF gain at its full normal setting and adjust the IF gain to where the basic background noise creates very little meter deflection.

Rodger WQ9E