You – you lucky devil – will be learning about tube testing today. But before we do that, a background course in radio repair as a warm-up…
It was a quiet weekend on the electronics bench as Universe had presented a mildly interesting case: A super cheap (Under $100 on eBay) radio – classic Heathkit HW-100 late 60’s vintage, I seem to recall
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Not a bad radio, really. Inexpensive, it was in the 100-watts output class and for thousands of hams, it was their soldering iron entry point to a career in electronics.
I didn’t have the time blocked to do a thorough work-up on this one – a more urgent radio was pending. But the initial pass through the radio revealed a non-functioning “loading control.”
This is nothing more than a simple variable capacitor – those things like look like “bread slicers” in the innards of older radio gear. What was unique about the Heathkit design was that the plate tuning and loading controls were on two concentric shafts. Tuning was the inner shaft and it was a solid rod from the front of the radio to the final amplifier compartment.
The loading was different. It was a co0ncentric sleeve that went to the vicinity of the outside of the final amp cage. And there, a large >1″ pulley was installed on the shaft. From here, the idea was that a soft rubber belt – scrounged from a plumbing supply joint – would run down an inch and a half to another pulley. And this pulley was on the front rod of the other capacitor – the one used for loading into the antenna.
There is a point to this part: My son rails at me constantly (when he’s not off working somewhere in the world) “Dad what are you doing with all these obscure parts?”
Whole thing was a 15-minute fix.
Yet today, there it was in the top drawer of the “Save me when I need it odd parts rollaround” – the precise and exact plumbing slip joint gasket that Heath engineers had used.
It was a grand morning, already, for the Radio Detective. I took a picture to put on the way: “This is why we hoard obscure but important radio shit around here…” reads a piece of masking tape (with three exclamation points following…).
I’m sure my younger sister (who is a professional hoarding fixer) would crack at such trivialities. But with 76 staring me in the face, I have no time to waste on shipping delays. Besides, my supply was bought at pennies on the dollar! Inflation’s a bitch – so when you pick a hobby, build in a Biden-Beater. Or a Fed F*ck plan. You’ll feel like a genius on the way out.
The SR-400 Case
Let’s begin with the evolution of Hallicrafters into Rockwell, first. Acquisition by Northrop Corporation: In 1966, Hallicrafters was acquired by Northrop Corporation, an aerospace and defense contractor. Sales slumped. Eventually, Northrop decided to divest or restructure parts of its operations, including Hallicrafters. They ended on the balance sheet of Rockwell International, another major aerospace and defense contractor. In the end, Hallicrafters died on the corporate vine as good people were offered other Rockwell jobs in automation or in Collins, a big name in avionics…
Now, with the backstory in mind, here’s what landed in the Radio ER this week:
The receiver in this is “hot as a $3-dollar pistol.” But the transmit side was non-existent. So it was time to start pulling the covers off.
The blue “A” is the rock solid VFO (variable frequency oscillator, the guts of tuning the radio). B is the amplifier section. Under the screwed on perf cover are two high power (relatively) transmitter output tubes. And the yellow arrow points to the black heat shield on the driver tube, a 12BY7. I’ve never (or more than 60-years of radio work) had very good luck with these tubes. Must be some kind of subtle astrological conflict.
IMPORTANT NOTE: Before opening radio, power supply is disconnected. Charged HV capacitors can kill. So all HV points in the now open radio are shorted to ground for safety! This is not a mistake you get do-overs on if you screw up. SHORT TO GROUND! Everything you want to touch. Anything you might inadvertently touch, too~
Regardless of reason, after having a quick “once-over” of the innards (looking for smoke traces and melted components) I was anxious to try the 12BY7 out on the tube tester.
Let’s explain the arrows. Top left, small yellow arrow points to the Sencore tester manual. When the clear plastic is slid to the down position, it holds the tube manual fairly flat and readable. Neat idea, really.
The lower larger yellow arrow points to the tube tester manual. It has two columns of information: In each, there is a tube number, which socket to test in, and settings that correspond to the four knobs which are to the right of our blue arrow above. Easy? The Major and I were doing this stuff at age 12. Except it was up at Owen’s Pharmacy up the hill; we we both poor to the extent that our parents didn’t provide suites full of test gear to “children.” (All has since been forgiven…)
Let’s focus next on the 12BY7: Here’s the socket number and settings dope:
The “normal short” is worth thinking about – lots of tubes have them. Here’s how the parts inside the 12BY7 are laid out:
We see that pin [3] is marked IS (internal short) which is internally connected to pin [9]. A lot of tubes so this because you can fit a component (to the suppressor grid, in this case) from either side of the tube which can make wiring more direct.
Also notice that for a 6.3 volt filament (heater) voltage pins 4 and 5 would be tied together and the 6.3 volts would be fed into pin 6. This allows (if you have a 12.6 volt filament winding) for one side to be fed to pin [4] and the other to [pin 5] while [pin 6] is left unconnected.
OK, so we put the settings into the tube tester’s A, B, C, and D positions, pop the tube itself into socket 12 and wait for the tube to warm up. Surprise! the 12BY7 is good!
If you ever find yourself wondering how long tubes should take to “light up?” The RCA Tube Handbook (depending on edition) specifies for (many/most) common receiver tubes a warm-up of 11.5 seconds generally, and 15 seconds being good.
Maybe my relationship with 12BY7’s has improved?
Meanwhile, Back in the OR
The Radio Detective considers his bench layout. The big yellow arrow left is the power supply for the radio. On the right is the radio itself. Between is the bench PC so I can eye the market now and then while working on gear…a small Win11 mini on the back of the monitor.
Looking at the clock? Time to go finish part 1 of this article, so the hand tools (so far) get tossed into the tool cases, the tube tester is stowed….
And the Detective takes a break to consider symptoms. Here’s the list for you to consider:
- There is plate voltage (draws >300 ma. when keyed so final tubes likely OK for now).
- 12 BY7 driver is good. We just did that.
- The plate tuning and loading controls are not changing plate current into a dummy load.
With a good driver, we look at the schematic and come up with a test plan: We will focus on the capacitors in the plate output circuit because a ground short on any of these (or the coupling capacitor C150 failing open) could all offer similar “no tuning outcomes.
That’s where will will pick it up next weekend.
Enjoy ham radio Field Day. See you on the low end of 40 M CW today and as the day warms up, onto the low end of 20-meters… first, a spin through 3806….
Write when you get rich,
George@ure.net ac7x
I fixed a couple of TVs back in the days of tube testers being in 7-11 stores, but tinkering on the innards of a radio never drew my interest.
Speaking of Rockwell, they also bought out Collins Radio back around ’71. I got caught in the ‘downsizing’ of Collins in ’72. Yes, I worked at Collins Radio, but not as a tech or engineer. I did commercial photography that went with their tech brochures and sales stuff. Hauling a huge case, tripod and lights to the various buildings to do my ‘light waving magic’ to eliminate shadows. The camera was an 8X10 Kodak view camera, and exposures at f-64 on Plus-X film ran a minute or more. The 8X10 negatives allowed using lithographer’s tape (transparent red) to block out the background so the equipment they wanted was all alone in the photo.
Now, there’s some lost art – lighting trumps everything I hear
When I showed up to shoot equipment, often an 11′ tall rack, I’d draw a crowd of folks to watch me walk around behind/beside the camera waving a 500 watt light with 18″ reflector in circular patterns while keeping an eye on the second hand of my watch. It must’ve been quite a show.
I think it was Ansel Adams (famous photographer of yore) who said,
“Photography is much more about light and shadow than it is about things.”
73
Amen….wheel Adams was my idol..
I always wanted to be the next wheel adams.. the kids always talk about big hunting trips and I could get into that..mountain goats grizzly bears..but I wouldn’t hunt with a gun.. A camera..
https://sharpshooterindustries.com/images/StockBipod.png
sadly it would be taken as a gun not a camera..
Ansel not wheel lol
What the blazes ? what in darnation ?
Dude what is that thing, an Edsel ?
Thinking here an cinder block might be cheaper alternative – Never Again Volunteer Yourself, from somewheres West of the Rocky Mtns – https://youtu.be/Ce9rSwNs7Hg?si=7P0Qspa_1PJOV2zG
Get an iCom, stop the risky behavior of f-ing around with high voltages. Elaine should be throwing Ure ass in the Penalty Box for this nonesense. I cant even See a Red Tag in any of these pics – what the what!
Safety VIOLATION – RED FLAG down on the Bench !
Radio9s live in fear of me – though I am meticulous in my HV technique. Keeps me sharp.
Safety 1st Kemmosabe..for Ures review – and all the other rogue radio techs out there reading and not comprehending what the outcomes of their reckless behavior leads to..dun,dun,dun -https://substack.com/redirect/667005db-7a4d-4773-8cbd-ec1be221dcc4?j=eyJ1IjoiMWtrNHlkIn0.fVVcJH6f1r_zprDxpYe9yhWMCY9me-zumT3TyeeDR9A
Remember HomeGamers – Only Youse Can Prevent Forest Fires.
Or, like we say, “Go Bear and don’t worry about the smoke…”
I don’t have a link, but I still remember the film we had to watch as an early 60’s vintage Navy electronic tech. It was titled “Your Deadly Shipmate”. After 10 minutes of cautions, it concluded with a sailor drilling a hole in a bulkhead, with a 480 volt cable on the other side.
I did get zapped good from a klystron on a 3 megawatt radar transmitter when the HV jumped from the Tektronics probe to my hand. I was out for a while, and woke feeling refreshed. Lesson learned the hard way.
Your deadly ship mate is on youtube…
https://youtu.be/jAVahRAsGpY?si=wtcjtA7TBOKoghl2
https://youtu.be/LSyN40xNpZc?si=jpau0Coh_TG4UVW1
they are all up ..that’s just two of them..I looked to see the film on rodents..
That iCom [nice kit] of Yours? Is that EMP resistant?
That Radio of Ure’s is.
LMAO……..
Got Blockchain?
Green star Smart Reader who gets it awarded!
thank you.
Don’t get me started on HV ‘accidents’ I have witnessed in my 40 year career in TV…. when a CRT had 25kv on it, even days after being disconnected. My radios now all run on 12 vdc… including the IC-7300. :-)
You know (after finishing the SR400 today) I am actually considering a brand new 7300 for the 76th bday next month.
It’s working on me, Hank…working on me…
Look deep into my eyes, and dream of bit-slicing incoming RF directly. You will not be happy until…
No tag, flag, or nag needed, if’fn one knows what they’re doing.
I got a 37kv wake-up call when I was about 15. HV box of a Silvertone color TV. Left birdfinger was securely gripping rearmost belt loop. That jolt was sufficient to deliver a lifelong impression on me memory banks. Once it registers, you strive to never repeat the event…
Speaking of Elaine and radio repair brings to mind something from the heyday of my ham receiver restoring, around the year 2000.
During those 3-5 years, depending on how you count, I had a good relationship with a pretty and smart woman who lived just 6 or 7 miles away. Looking back, it was the relationship with her that gave me the calmness and completeness to my life which allowed me to focus so fully (as George describes now) on the restorative, intricate, and salubrious job of fixing these things up.
Without that restoring the radios never had quite the same results as I seemed to need to spend more time on personal survival type things…
I’m impressed! I don’t keep much extra basket material around as the reed cracks when stored too long. But I think I’m going to stock up on handles, wooden bases, and sea grass, all which last forever. Good idea.
Most of you probably know that corporate Joanne’s is closing. A local employee told me that all the stores are closing in February or March. A few things are on sale but they are not restocking. Now is a good time to buy a few patterns, sewing machine needles, or other sewing supplies or whatever craft items you prefer.
I hear it is hanging on by a thread.
Cut the puns, pleats
Will Walmart be the only place left to buy fabric?
Try Amazon…
I need to feel fabric before I buy it, which is one of the reasons I never buy clothes online, either. Joanne’s closures will be a huge blow to an occupation/hobby that has been slowly dying, but will be valued and necessary when SHTF.
Michael’s and Hobby Lobby are both far better than WallyWorld.
Jo-Ann’s 2nd bankruptcy in the last year. The raiders who bought Big Lots put in a lowball bid. Jo-Ann is soliciting other bidders. The grapevine says they’ve got between 23 and 37 B&M losers, but I find it hard to believe 5% of their retail outlets could drag the whole chain into the ground. If true, their ~760 stores that are running black ink are barely doing so. Local store is in a 70yo strip mall and typically runs one POS-jockey and one cutter for 8000sq.ft. of retail. Their issue has to be pricing. Maybe they should stop allowing coupons to stack, or better-select seasonal fabrics, ’cause they can’t cut employees or overhead any further.
That news really made my wife sad…Joannes fabrics is her favorite store. I get a good feeling watching her sew..
her mother use to do lacemaking.. wow
Bear-on-the-Boat wrote: “The Radio Detective considers his bench layout”
Uhm, what bench? Disingenuous to say layout. Looks like a sprawl methinks. Why does every horizontal surface invite collections? Mine, all of them, are just as bad but I don’t publish photos of my stuff.
All the BoatHouse horizontals (two formica countertops) are covered in end of year pier-jerk bits and pieces which, will be needed in a few months. The garage bench was crazy clean and then I managed to cover it with tool clutter in no time. I have (4) monster industrial steel workbenches in the barn, all packed with tools. And, the 20′ bench set in the barn toolshop is a joke. Need spare time.
ATL: day 1 of the DN Iceboat gracing our 7″ ice cake. We need some of the surface snow to layer up then will have a new game until spring thaw. Fleet Captain (FC) took the Inaugural spin and we hope to sail every day through mid week. TBD.
Stay warm,
Egor
ps – cold on the ice. I’m breaking out the Arctic Issue Mickey Mouse boots
Um… I consider it “Documentation of Gravity Effects.” Held over any horizontal surface, shit will cover it.
(“cold on the ice. I’m breaking out the Arctic Issue Mickey Mouse boots”)
the best snow boots I ever had came from Antarctica.. sports equipment usually are targeted by season..so the really good stuff is sold by regional temps. I need slightly warmer boots because I froze my feet walking to work in winter with o my tennis boss on..
the air force supplied the ice with new snowboots..the problem was.. they had steel toes. steel toes down on the ice will cut your toes off..so they were burning them in their heaters.. since I needed a new pair that year they sent me a pair.. in our northern but not arctic circle dam they were the warmest boots I ever owned..
when they wore out I was in a blizzard all the warm scrap on.. visiting with one of the survivalist on naked and afraid ( laura) she was stuck in her car a few miles from us and as I came around the corner I said..you were on naked and afraid..do you want to see named and stupid..there was my grandson fifty below zero forty mile an hour breeze in shorts flip flops sweatshirt and a stocking cap scooping snow..
it was a funny sight .. but she told me where to go for your winter duds and those wonderful heavy duty socks..
https://mukluks.com/
https://mukluks.com/products/icelandic-ice-socks-j-b-fields
Here’s the socks..dam warm..
Cold as a Witches tit..colder than brass toilet in an igloo, freeze the Balls off a brass monkey?.. that chunky monkey..? https://youtu.be/nBbQyXZvkbA?si=8aebCrgk7ov9V4aWy-
No, brass monkeys are not chunky as general rule. But if exposed to cold enough temperatures as to effect contraction and expansion of Brass Balls..well then yes they will fall off and roll away..
How come about 1st hand knowledge of said frozen brass monkeys ?
Tall Ships – Philadelphia .
Biggest question of frozen Sunday in late Jan – whats “current” on Ure workbench ?
Here in tropics Garden Bench is most “current” wit 2 Papayas Trees, 2 Vietnamese Vanillas and a Trumpet Tree (devils trumpet) that need planting.
Fishing/Boat Bench – bit of a mess..a little Idle Control Motor-Suzuki DF90, and a Throttle Control Body.
Just diagnosed and removed yesterday. Next Saturday hope to be back on da Water hunting for my dinnas. All else fails out there spearfishing- I just resort to slamming Lionfish, and throwing them at the boat upon surfacing. Gotz to be Ure toes when out on da Water with an amphibian type.
* Local Artists use the spines of Lionfish in Jewelry making for the touristas.
*Dead of Winter – trad is Furniture making, See Shakers/Quakers/PennsyDutch in Pennsyltucky. Dont forget to cut enough blocks to Fill Ure Ice House – should be plenty of sawdust from all the furniture making.
I just ordered our seeds … got double the beets.. I thought I made enough beet pickles for the year. shoot we are down to two quarts left..
Never sailed an Ice Boat … but sure looked like fun when I lived in north mid Michigan. Only did cross country skiing up there, but was out 4 to 6 days a week going across the lakes, through the woods, and enjoying the wildlife. Found I really liked a hard winter, with the proper clothes it isn’t a bad way to spend a few months.
Still have my LL Bean insulated Duck Boots that with replaceable THICK wool inserts from those days. Still work wonders at keeping the feet warm … if it is AT LEAST zero, 10 or 20 below is better. Above that they are sweat boxes.
When you are dropping 75% of the paychecks a month into a bottomless credit payment pit, minimalism is a lot more appealing, if not a grim reality. Revel in Ure parts clutter.
Couple of years back I took more than forty lawn leaf bags of useless crapola out of the attic and garage. I need to dispose of more. But not in the name of minimalism. I need room for more relevant stuff. Long live useful clutter.
God, do I know that one! What is cool, though, is that as part of Ure’s “Live Long and under the radar” is that all this old radio gear does have collector value. And – the best part – is that if you can contain your top-line income, the long-term gains rate comes down.
So let’s say I have $40,000 of hobby radio gear that I get rid of. Since it was all acquired >2-years ago, no question about long-term gains. Yep, you bet. Sure, I can go back and do the whole cost of acquisition for each unit I’d sell, but since I’m already in the tax sweet spot (cap gains rate of zero) who cares? God knows we don’t need more work on the way out…
But the tax rate for MFJ couple of LT gains is what? Here are some hints: https://taxfoundation.org/taxedu/glossary/capital-gains-tax/?utm_term=capital%20gains%20tax&utm_campaign=TaxEDU&utm_source=adwords&utm_medium=ppc&hsa_acc=7281195102&hsa_cam=10677477086&hsa_grp=122188010616&hsa_ad=519053786785&hsa_src=g&hsa_tgt=kwd-13279012&hsa_kw=capital%20gains%20tax&hsa_mt=b&hsa_net=adwords&hsa_ver=3&gad_source=1&gclid=Cj0KCQiA19e8BhCVARIsALpFMgHBGraMGUhJ_vi6rtzvORQVm_lv16P42MdZZjIH-vfrZOhc9MOb210aAkRLEALw_wcB
In other words, since we eliminated all debt, and I structure income so we are under $94,000/year, including radio gear if I sell some, then the radio sales cap gains rate is?
ZERO!!
So, figure’s aye, the government must want me to do this (tax-advantaged) hobby!
Of course, if I accidentally make more than $94,050, which we try to avoid, anything over that is only taxed at 15%…so yeah, have fun and enjoy life!
Taxes are only on gains, not on total revenue from sales of long-term (in my case hobby) assets.
(“What is cool, though, is that as part of Ure’s “Live Long and under the radar” is that all this old radio gear does have collector value. And – the best part – is that if you can contain your top-line income, the long-term gains rate comes down.”)
growing up there was a guy he had five acres on the edge of town..that had piles of stuff buildings of stuff.. if you needed to get rid of something you hauled it to him he would say put in this or that pile or that shed.
if you needed something you’d go ask and he’d say look in this or that pile.. at one time he was the mechanic for carnival rides.. he died.. his wife was in tears talking to an auctioneer in our community.. he told her don’t worry we will take care of it for you..
every week they would haul a pile out..advertised it all over.. movie production teams would come and buy it.. he had the original television station beer that ended up in a few movies the old party line switchboard.. ( we were seven rings the pause) by the time they were through she was a multi millionaire and all the piles were gone..
That’s the ticket – have fun, make shit, help others, and roll on the grind, brother.
That is a helluva good retirement income for a cash sort of guy. Maybe you do need a travel van or something to waste some money on.
For me, the retirement wild card is social security. If I continue to work a few more years until age 70 before full retirement, I won’t be drawing maximum SS rate, but I’ll be close. Waiting until 70 increases the draw 25%+ over the 66 and some change retirement. SS is calculated off the best 35 income years. I still have a few years that are at a mean rate about a third to half of the remaining years that I need to drop of the calculation ledger, so I will get another boost from that. Those few adult years I only had unearned income cost me on the SS calculation, but I will have it largely made up before I lock in my payment. For those of you who don’t have a readout on anticipated SS benefits, set up a SS web account to monitor with. Same for Medicare.
I am still saving all of the interest in tax deferred savings, and I will probably restart my 401K draw, which I suspended until I had some things worked out with the employer. Negotiations were successful, and it doesn’t look like I will be forced to retire at full retirement age (or before). I am becoming more optimistic about 2025 and prospects for a fully funded retirement in a few short years.
Current Value Cash = +++++++
Opportunity Cost = – , -, -, -, -, -, -, -, -, NEGATIVE .
How much Mag 7 stocks appreciated in last 10 years ?
How much BTC appreciated last 5-10 years ?
How much Dividend Income Collected last 10 years, and REINVESTED ?
How much Interest Income from UST’s…..
You be trying to Maximize a RIGGED Game. Maybe, just maybe think OUTSIDE The Box, and change the Game a lil, and or make Ure own Rules..
Lol lol lol ..when I was young how things worked was a big deal..I collected patterns plans and if you haven’t heard I read a little..love books.. I had a full garage of books and tools.. the wife got irritable and insisted I get rid of the books so she can park in the garage..
her new thing is I have my extruder out.the plan was to set up a table with the extruder and corn canon there to show everyone now like puffed wheat or rice and corn curls are made..at the farmers market.. then hand out bags of cheese or peanut puffs..let them drop donations for the local pool repairs for the kids..
https://youtu.be/JzzyQRfdR6M?si=FnxVPL2dTaOpVRT7
.https://youtu.be/S59038lV8Ho?si=vbeJ6Kr41SvBx06e
I like how this guys canon is set up..I actually took of the pressure gauge to put a relief valve on the back. instead of popping it open at ten pounds do five.. not as big of kabang but still enough pressure.. the other thing is I wand a grain cage….
https://youtu.be/SRHlEMlfArA?si=pOe-e6deXQulVZiZ
set up the candy planner for peanut flips..
(“Dad what are you doing with all these obscure parts?”)
how did that go over?
my son inlaw kept at me about my garage.. I don’t get upset easy and I don’t care about the stuff. But for some strange reason I felt as if I had lost control..
Yu can make a dandy “EMP Bucket” out of a METAL garbage can and lid. You don’t need any exotic materials — a standard galvanized steel garbage can will do fine. (Copper or lead will perform no better.)
If you like, you can add a steel wool gasket around the lid to improve contact, but this a refined nicety, not required for sufficient performance to do the job.
Place the can on a piece of wood to keep it off the Earth ground or concrete floor. You can put your protected equipment on a chunk of wood inside the can also if you like.
Key concept: EMP comes in a wide variety of strength levels from “hardly there” to “fricasee your hearing aid” It all depends where IT is, and where YOU are, and how powerful IT is, when it goes off.
With radios, sometimes just not being connected to an antenna or power lines will be enough. Some older radios are built into metal cabinetry. This helps some.
Generally, solid state (modern) equipment is more suseptible to EMP than older (vacuum tube) radios.
Some older radios, however, are a mix of tube circuits and solid state devices.
For an “EMP Bucket” the main protective feature is the EMP wavefronts are merely reflected away by the shielding effect of the metal. “Reverse EMF currents” form in the shield, and that cancels the incoming field.
Copper will do no better. Steel is fine. Keep the can off ground, and keep the gear inside insulated from contact with the can.
— and pray it never needs to be tested.
73
73
The 80 dB RFI adhesive gaskets work well for the lid, and aren’t that expensive. All the electronics houses stock them. I line the large cans with cardboard, and set them directly on the concrete. I have one small can that is lined with a five gallon bucket.
I put everything inside the can in aluminum foil, or better yet, wrap with foil and put in a dry bag for both EMP and moisture.
Do you think that a piece of cardboard underneath the can would be an improvement, William ?
One thing that I think will help is a sheet of carbon RFI absorber material placed on top inside. I have a little 20dB carbon absorber material I got from an EMF shielding paranoia supply house. I suspect that a sheet of 30# tarpaper would probably work about as well. My walls and roof have 30# tarpaper on top of the sheathing, and I only get decent cell signals close to a couple of windows.
You touched the key word: “attenuation.”
In RFI / EMI / EMC stuff, loss or protectoin is measured in “how much?” and not in terms of a perfect shut-off or total exclusion.
Decibels, (“dB”) is a relative measurement. If one thing is ten decibels down from another, it’s one-tenth the strength. If is UP 30 dB, then it’s a thousand times stronger: dB is a measure of relative strength. (The “B” is capitalized because it’s a guy’s name — as in Alexander Graham Bell.)
Every ten dB is a ten-to-one ratio. (Sorta like the earthquake scale,)
In shielded rooms — for either containment OR exclusion of signals — a “60dB room is a million times attenuating of either inbound or outbound radio frequeny fields. That’s a lot.
Government SCIFs (often conference rooms said to be bugproof) are sold and rated at 100 or even 120 decibels in atttenuation. This is high perfromance, and doesn’t come cheap. And mostly more than they really need.
My Kentucky spit-windage guess of the garbage can EMP Bucket’s shielding efectivenes is maybe 40 to 60 dB. That’s a lot of protection in the real world. Leakage from smalll spot locations (gaps — mostly the lid)) would be the main de-rating factor. I’d expect a well-sealed up garbage can, with no leakage paths, to easily exceed 90 to 100 dB in attenuation — shielding effectiveness.
I recall that Arthur Bradley was of the opinion that somewhere around 50 dB of attenuation is sufficient for protection of consumer equipment against a HEMP event. I would guess that a lightning EMP would require better shielding. The combination of the bucket, the foil and the dry bag should get you there. You inspired me to stick a piece of cardboard under the cans.
Yes she’ll bucket is nice …But….if there was a Carrington event… and your in the epicentre… how many miles of wire do you have on hand…
One of the guys that lived in our spare room was a hundred year old man..he would tell me stories of having to string five miles of wire when rural electrification first came out..just to get it from the electric line then to his farm ..the cost of the poles back then you had to string it yourself..
if your in the epicentre all the insulation would be burnt off for a few miles..
“how many miles of wire do you have on hand…”
About 40.
School was liquidating wire spools about a dozen years ago. I thought “trailer park lawn furniture” and bought a trailer full at $5-$8 each. I had no idea until I arrived to pick them up that they contained significant scraps of THHN, stranded UF, 1,2,4,5 conductor shielded, mic cabling, RG-{damn’ near everything}, and various flavors of 4x/6x/8x COMMS cable.
If’fn y’all ever get bored, doing the “Mike & Frank (RIP) thing” is a fun adventure, and it sure does fix that problem we all have, of too much open space and not enough clutter…
And if you want to find out how that garbage can will actually work. Take a remote temperature sensor, like the one that came with my digital clock, and put it in the garbage can.
Even the weak signal from that temperature sensor will easily pass through the can and still be strong enough for the temperature to be read on the clock in my living room. The electromagnetic radiation from an EMP will be MUCH STRONGER.
Galvanized Steel? Really? No. I’ve tried it.
With respect, no, you haven’t tried it. EMP has not been tested by us. Yet. (Hope it never is…)
If your can leaked RF at 300 mHz — about where these remote thermometers work — then it’s the leak that’s the problem, not the material.
I kniw what I’m talking about. I’ve tested RF shielded enclosures in the field for years. If they de-rate from purchased spec, it’s a leak, not a bad material choice.
Try the same experiment with your microwave oven. They usually shield pretty well.
Or try with a portable FM radio. Even the strongest local FM signal will not get in past a closed door. (Unless you have power leads for the radio, bypassing the closed door.
Maybe an old microwave oven…
Depends on the EMP source. HEMP radiation is little more than a wisp of energy- the EMP from a nearby lightning strike is orders of magnitude more powerful. The difference lies in the rise times. The rise times on HEMP impulse are down in the low nanoseconds. While the energy is very low, it blows right past slow protection devices. Also, I have heard that the HEMP frequencies can propagate across open switches, so having the power turned off may or may not help. I’ve never found anything that will 100% protect my off-air coupler board on the TV antenna. It’s been out for a month after a relatively mild lightning event. Been enjoying the peace and quiet.
Arthur Bradley has done a lot of testing on his EMP Doctor website. He has really sensitive test equipment.
“Why Property Tax Is Illegal”
https://www.zerohedge.com/economics/why-property-tax-illegal
Money grabbers running roughshod over the law.
re: “The Hitchhiker’s Guide to the Galaxy”, 2005
feat: Ursa Major, Ursa Minor
Folks,
Move over Twenty-second Amendment! President Lukashenko marked his ballot for a seventh term leading Belarus. He was accompanied by his white Pomeranian, Umka (‘Polar Bear’), who also reportedly left a mark at the polling station. The President suggested the latter’s message was intended for critics at the EU.
Pomeranian dogs were apparently first introduced to England by the wife of King George III. Queen Victoria’s Pomeranian infatuation made them in demand by 19th century Royal Families. Despite such popularity, a postage stamp does not appear to have been issued until 1972 in the Sunni Muslim former British Protectorate of Sharjah believed by some to originally have been called Abed Al Shareq.
re: “The Proposal”, 2009
feat: like a Norman Rockwell painting
Folks,
As a leftist South American president showed his guerilla roots, the universe winked in television schedules. Sunday evening a subsidiary of the Magic Kingdom aired a 2009 romcom “The Proposal”. A Canadian in America facing deportation visits her fiancé’s family in Sitka, Alaska. However it turns out movie filming actually took place in Rockport, Ma.