Hammarlund HQ-110-AC on the bench!

[KI4YAN]

I recently was gifted the above radio in working, although very dirty, condition. Unfortunately, I'm not entirely sure if the radio has the Silver Mica Disease or not...it seems to work fine, however the noise floor is pretty high. I have done the audio mods detailed on the AM window and they made a big difference in the listenability.

Anyone have any tips/experience with this receiver? I'm currently feeding it from a 40M dipole, 50ft or so of RG-11 coax into a 75R-300R balun at the receiver. The center of the dipole is 38ft off the ground, the ends are about 30ft off the ground.

I can receive a LOT of stations, AM and CW, but SSB just sounds...garbled. All the time. It's pretty rare that I can tune in a sidebander and actually hear what they are saying. That, and some warbling chirping QRM on 3885 is just wiping out the AM activity. I can copy a few stations, but no one really stands out in the crowd.

[w3jn]

Does the noise go away when you disconnect the antenna?  You'll get *some* noise with no antenna but it shouldnt be enough to deflect the S-meter.

If you still get tunable noise with the ant disconnected, there's trouble with the oscillator/mixer.  Try a different tube - Hammarlunds are notorious for being picky about the 6C4 LO tube.

[KA2DZT]

I would removed the 75-300 balun.  Just connect the coax directly to the terminals,  one of the terminals is at RF ground.  I have a HQ-110 and thats how mine is connected.  If the balun is one commonly used for TV it may not be good at low shortwave frequencies.

SSB reception,  you may have to reduce the RF gain control to get the sideband to sound good.

Hammarlunds are notorious for having bad IF tramsformers

[WQ9E]

I am pretty sure your A version doesn't have the earlier (and very troublesome) open construction silver mica caps in the IF transformers.  This doesn't mean that the dipped units don't ever go bad but that is not that common. 

For SSB operation alignment could be one issue.  As a first check, the tone of the background hiss should be at the lowest when the Pitch control is centered and should increase in pitch either side of center.  If this is off then your initial setting of the control for either LSB or USB reception will be incorrect resulting in poor SSB intelligence recovery (assuming there is intelligence to recover which is a problem with some SSB groups!).

The HQ-110 is designed to be used without AGC on CW/SSB so the proper setting is AGC off with the volume set to at least the half full setting and then control the volume with the RF gain control.  Otherwise there will be insufficient BFO to signal ratio.  If there is a problem in the audio section of the receiver resulting in low post detection gain then this will cause you to use excessive RF gain resulting in a lot of noise and poor detection.

Night time operation on 75 requires a receiver with good selectivity and the HQ-110 will benefit from the use of its Q multiplier once you get the hang of using it.  Keep the Q multiplier setting very low until you get some experience in using it; too high a setting results in difficult tuning and muffled audio on the voice modes.  You might experiment with the receiver on 40 or 20 to get more experience with how it "handles" on a band with a lot less QRM and QRN than 75/80.