Serious turntable popping problem finally solved!!

Well, for the past few years I have experienced a huge sonic pop going thru my system that has baffled everyone who has kindly offered to help. It has been strong enough to blow out fuses on the power amp and short phono stages. Basically, it's rendered my better turntable worthless. 

A little insight, the problem only occurs when playing a turntable through a higher end phono stage. Through a lower end (heavily shielded) phono amp - no issue. Hence, my Shinola Runwell (a gift from a very kind friend) with built-in phono had no issue. 

Today, finally, I figured out the problem!! It turns out it was the cellphone backup radio connected to my home alarm system.

Big shout out here to Carl from Apex Audio here in Denver who has gone so far above and beyond in pushing me not to give up and has helped me isolate the issue down to an airborne RFI. From there I was able to figure out the longstanding culprit. He has also worked on grounding issues, new cables, loaning amps etc even extension cables to run my system off my neighbor's house power whilst killing my house power. 

Long story short, the cell phone radio backup has a back up battery making it the last possible culprit - even when my house power was shut down. 

Now I can finally enjoy the Vivid B1 speakers I purchased from Harry, an Audiogoner who has been such a pleasure to know via email. And also my new Aesthetix Janus preamp, and compete Tara Labs package courtesy of Carl. Btw, Jim from Aesthetix was also incredibly helpful with tips and his willingness to help find a solution.

Now I can truly focus on listening to beautiful music through my 35 yr old Linn LP12 and get back to the real point of being an Audiophile: Critical obsession of everything that is wrong with my perfectly good system so I can upgrade!!! 😂😂😂

Thanks to all who have helped,  especially Carl and a mention also of the good folks over at Crescendo Audio and other friends who have put up with my frustration over the past few years. 

Gotta go, got new vinyl to hit...... 

That's great news! 
Thanks for posting the cause of the problem.
Enjoy your music!
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Thank you for the follow-up!And I'm very happy for you for the end of your frustration:)
So, how did you fix it?
First step @dweller was to isolate that this is the issue. Pretty simple. Disconnect the radio from the antenna and power. Done. Turntable played like a dream all day. It was located a few feet away from the audio (basement) in the adjacent mechanical room, separated only by sheet rock. Alarm company will relocate the radio to the garage which should solve the issue. 
Thank you so much @Lak, @elizabeth and @jtcf. Yes, huge relief. So lovely to hear my system perform the best that it can. My old Linn has some typical Linn-like issues but it's still plenty musical. Has a Graham Phantom arm and Clearaudio Concerto cart. Next step is likely to replace the Linn and get a deck which better suits the Graham arm. Transrotor is the front runner. 
Perfect example of why these kinds of noises can be so hard to track down. Once you get past the first few obvious things to check it quickly gets into a near infinity of possible culprits. You can't just say check this check that. You have to say check everything that has anything to do with electricity. Some of the stuff Keith Herron told me he's seen had me shaking my head. But cell phone backup radio battery charger, that may be the all-time best! Well done!
This case reminds me of the one posted where an alarm
remote alert feature was the cause of plenty head scratching.

To be clear @millercarbon it was the antenna signal that was causing the issue but it was the battery backup to the device that caused me to miss this possibility when I killed the Master power in the house.

Plus side of all this, I have a dedicated circuit now, better power conditioner and new preamp all as a result of trying to solve the problem!! 
I'm not sure what a cell phone backup radio is, but glad you figured it out.  The RFI could happen to anyone.  My security system is a cell phone run system too, but haven't had any noticeable pops.  Occasional static but that is nothing  out of the ordinary.
Hi @pgaulke60. It seems to me that the level of interference will depend on proximity to the system of the antenna. It's literally just a cell phone signal connected to the alarm. It provides a secondary communication to back up the phone line. Very commonplace. A little surprised this hasn't affected other people on AG. Btw, no issue at all with digital or heavily shielded, more budget level phono. 
OMG!  What a horror story.   I couldn't imagine shutting down the power in my house to resolve that.  I too once had a horrible pop in my system.   It was so long ago I don't remember what it was.
Congrats on solving your problem.

The amount of RFI power at play here reminds me to say to everyone- keep your cellphone away from your head. A few medical professionals I know have been talking about evidence (anecdotal) they are seeing which shows a rise in brain cancer that correlates with the increase in cellphone use. Now, with 5g coming, we will be bathed in this stuff.
Although, @stttt, you would be amazed how fabulous your system sounds when you cut ALL power except one dedicated circuit! The sound just appears from a far darker background than one can usually hear. It certainly makes you appreciate how important a lack of noise can be in shaping the actual sound. 
Question: what type of cell phone radio was it? Do you know if it can be replaced with a 4G cell radio that should produce less interference?
@sleepwalker65 It's being moved away from the system. It won't be an issue. If it is, then at least I know what's causing the problem and will deal with changing out the radio at that time.