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THE AM BULLETIN BOARD => Technical Forum => Topic started by: KW4H on September 10, 2021, 11:42:09 AM



Title: HRO-60 Coil Pack Alignment & Down-Dial Sensitivity Loss
Post by: KW4H on September 10, 2021, 11:42:09 AM
Iíve been cleaning and aligning the coil packs for my HRO-60 and have run into a curious anomaly:  in general coverage, the sensitivity drops significantly at the lower end of the tuning range Ė for example, a whopping difference between S9 at 14.400, and S2 at 7.0.  You can hear the background noise begin to drop like a rock about halfway down the dial Ė and adjusting the ant tune doesnít provide enough compensation.  This is happening on two coil packs (havenít aligned the other two yet, they're still being examined and cleaned up).  Iím assuming it might not be the coil packs but something in the 1st or 2nd RF amplifier sections surrounding T-1 and T-2.  Iíve stopped what Iím doing to consider this and find a solution.

FYI -- Iíve found, in the coil pack alignment process, that adjusting the inductors for peak signal at the low end of the tuning range produces little to no response.  Any difference in signal level is vague.  If this behavior is abnormal, it might be an additional clue that something around those coil packs is affecting performance.

Appreciate any/all thoughts and advice.

73 - Steve, KW4H


Title: Re: HRO-60 Coil Pack Alignment & Down-Dial Sensitivity Loss
Post by: KW4H on September 12, 2021, 10:17:14 AM
So this posting doesn't hang out there with no further information -- the issue appears to have been resolved, and was caused by two factors.  One was a rather significant impedance mismatch at the antenna input, the other was that the prongs connecting to the coil packs needed additional cleaning.  The latter seems to have resolved the matter more than the former. 


Title: Re: HRO-60 Coil Pack Alignment & Down-Dial Sensitivity Loss
Post by: w3jn on September 13, 2021, 06:33:06 PM
Steve, thanks for posting the followup with the resolution.  Too many folks that come in and ask for help get advice and leave things hanging.  Posting the resolution of the problem will undoubtedly help someone out in the future. 

Sorry you didn't get an answer.
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