I need an Audio Detective

@jr96aolcom

For over 25 years I was Chief Engineer of a number of both FM and AM radio stations. I was always on the hunt for a tuner that provided to me at home (to monitor the audio quality of the FM station’s I engineered) the same performance of our station’s modulation monitors (which sample RF directly from the station’s transmitter output - no multipath of any sort is introduced). I found that one day in the Yamaha T-85 (I also owned a MR 78 at one point in time). If you’ve never tried one...

I was actually able to confirm the audio performance of the T-85 by installing a few (at different transmitter sites), and hooking them up to an A-B audio switch (A being the station’s modulation monitors, and B being the T-85). With audio levels matched, I could easily switch back and forth between the two, and the T-85 always sounded almost exactly like the modulation monitors. Just in case you were interested.

One last thing; for outdoor FM antenna reception, many times I used lower loss Belden 9292 (RG-11) over various RG-6 cables. It’s harder to terminate (as RG-11 connectors require a special crimping tool), but can help with fringe reception.

Belden 9292

@erik_squires 

Erik has it right, disregard my first post.

I don’t keep the DAC on but you will have to admit this is a head scratcher

Um, no it isn't!!

Anything with a computer or DAC generates some RF.  Your particular situation is just more noisy than others.   I'm not sure why this is a puzzle, really. What's probably happening is that the RF from the DAC is broadly across the channels you are trying to tune, and it's lowering the quality of the signal lock.

Follow up all 4 of my tuners are behaving in the same way and the other two are on the left side of preamp nowhere near the DAC and it’s interconnects or power cable. The interconnects only get close where they connect to preamp. Thanks for all your thoughts. Like I said not really a problem I don,t leave DAC on but the curiosity factor was quite interesting 

erik_squires

Sounds like RF interference. 

I want to point out though that this isn't much of a problem unless you like to keep your gear warmed up.  Distance, shielded interconnects and shielded power cables are the usual solutions.

Awhile back I read a lot of claims that equipment sounds best when left permanently powered on. 

Could it be the opposite is true and powering off after each listening session and then powering on 30 minutes before the next is the best option?