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Hopefully not a pressure washer...

...unless you have lots of concrete to wash, one of the few safe uses for a pressure washer.

Its amazing the amount of damage that is done by pressure washers when they blow water past seals and into bearings or worse brake calipers. The other day I cringed when I watched neighbor kids line up their bikes for a good pressure washing from a well meaning neighbor. I wonder if all the bearings are shot yet?

From the size I guess window AC.
 
OK, a little history lesson...

It wasn't until 1968 that the federal government set radiation exposure limits for consumer devices. With microwave ovens becoming popular and GE's color TV x-ray debacle, the feds got busy. The regulation set exposure limits for new and 'broken in' microwave ovens and also required two forms of interlock. As far as I can tell, this mechanical lock was Amana's solution. The rules went into effect Oct 1970 so the timeline matches.

Of course other manufacturers were playing with similar locks or dual interlock switches, but unfortunately the probability of dual interlock switches failing was surprisingly high, especially if both were in series and an overload occurred. One study found 600 units of a popular model to have at least one shorted switch, and 60 of those had both switches shorted! Because the switches are typically staggered, it would be possible to get a brief, high impulse exposure even with the one failure. A company that rhymes with Feneral Selectric had a lot of issues.

This happened to occur the year before the '70 rules went into effect and started a lot of people thinking. New rules were drafted that required dual switch interlocks that were capable of being monitored, and if either or both failed, the machine was required to become inoperable. While just as safe, Amana's mechanical lock wasn't going to meet this requirement, and was redundant if a monitoring circuit were added (as required).

I don't know when Amana stopped making the 3H, and I've only ever seen one other example (in addition to the remains of a panel I have) It has a plastic screen liner and glass inner door like the 4 and 4D, but is the only model I'm aware of with the LOCK slider. I've gone through the literature and haven't found any reference to a straight up 3, either. Interesting stuff!
 
At last!

Cadman: I knew it was an Amana from the get-go -but I could have been easily wrong. Maybe it was my recent visit to your radar58.com page a few days ago and looking at the micro-convection model(hope to find!).

Now your remains of the RR3-H can be replaced with in a photo of a full unit(I know..not likely to happen soon).

How many of these have actually survived the dumpster/crushers? Nice find, congrats! And thanks again, for having a reference of Amana's. They're still a work of art.
 
That's a great find!

What does the "H" stands for?

So the RR-3 introduced the door glass and ventilation system, had the new background for the timers but still had the blue "light" switch. Were they the first with black trim around the timers or did some late RR-2 models had it too?

 

Do you have links to articles where they showed the stats about safety switch failures o different brands and which models had these issues? I recall seeing one which showed models which were more prone to "leakage".
 
Very nice RadarRange.  Thank You for explaining why this was a big deal in MW evolution.  alr
 
Darn

I was  looking forward to winning some new luggage or a recliner. 

 

I remember it being a lot of years that CR wouldn't recommend them because of the leakage issue. Wished they had all their old mags online.
 
Pretty cool microwave Cory! I am amazed that the interlocks were that easy to defeat and that prone to failure. The 'Lock' setting reminds me of the self-clean ovens that used to have the manual locking mechanism. Thanks for the background information and the pictures!!
 
Thanks guys!

Phil R, you're correct, this model introduced all those features. I also forgot to mention, you can't physically press Start unless the lock lever is engaged, and unlocking automatically forces the Stop button in.

Service lit says the RR-4 was introduced in '72, and the RR-2 was still in production in '70. That would make the 3H a 1 year only model, and my serial tag and the one other known example are both '71 date codes.

For those interested in additional reading, the link below takes you to an article on the interlock situation... And the NCBI link is a survey performed in Arkansas on microwave ovens in use at the time (prior to the Federal law, regulations were managed at a state level). I think I'll avoid the Littons and Tappans. TYVM!!

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1775150/?page=1
http://www.jmpee.org/JMPEE_PDFs/09-1_bl/JMPEE-Vol9-Pg3-VanDeGriek.pdf
 
RR-3H

Neat rare Amana MW oven, and I enjoyed the history about the development of the door interlock system used on MW ovens.   On my old 1958 and 1962 Westinghouse built-in MWs [ both built by Tappan ] there is just one simple door switch activated by the left hinge arm to cut off the oven with no latch or backup switch of any kind, makes you wounder how often that could fail.

 

  In our W Va home we have a 1969 Tappan built-in wall oven where the top oven is a 1000 watt MW oven it this one only has a switch activated by the male strike on the door and an added hidden reed switch behind the model # tag that a hidden magnet in the door operates, it would be very easy to fool this system with a small magnet and the tip of a pencil.

 

But since MW leakage is not all that dangerous there is probably more concern than real danger to having a MW oven in your house. The last time I saw statistics for MW oven safety there had NEVER been anyone harmed by microwave leakage from a MW oven, if you think about this this would probably make MW ovens about the safest electrical item in any home.
 
What's Also Neat:

Is that while this system didn't work out for Amana, they evidently put the control panel tooling to good use when they were working on the RR-4D; the RR-3's lock button setup morphed slightly into the control setup for the new defrost feature.

That's a proper respect for costs, unlike today's approach, where many appliances get re-designed from the ground up, using little or nothing from previous versions, with cost containment coming from execution in the cheapest and flimsiest materials.
 
Harm from microwave leakage.

to categorically say that harm from microwave leakage doesn't exist is wrong. Bodily harm from non-ionizing radiation is slow and possibly cumulative. Its not like someone touching a hot element and getting a burn. The cause / effect isn't clear.

It is equally incorrect to say that low level microwave oven leakage causes harm though, that can't be proven either.

The one point I always make clear, is that anyone concerned with microwave oven leakage, better not EVER come within a few feet of a cell phone without being more concerned about that energy. The field strength of the 1.9Ghz signal from a cell phone at even a foot distance is thousands of times stronger then the leakiest microwave you have ever seen. The potential for damage from cell phones is much greater then one would ever see from a microwave. Even being in the same room at a WiFi router exposes the user to more microwave RF field strength then an oven would...
 
All things in moderation....

My biggest concern is accelerated cataracts with long-term, repeated exposure, but these Amana ranges are some of the best made, and all it takes is a quick check with a leakage meter to see if we've got a problem.

John, now those Tappan's sound like a scary time. I think we'd all enjoy seeing some pics of your machines! -Cory
 
Cory:

I am glad you got this. I saw this on CL and wanted it, but couldn't figure out how to ship it.
 
Travis, I don't think I ever saw an ad, this little number came out of Rhode Island. Got a link?

There was an RR-2 advertised not too far from you as part of an estate, but it appears to have sold pretty quickly.
 
Cory:

My mistake then. This is a picture of the one from Joplin. I figured it was an RR2 or an RR3. I was told someone in the area was coming after it. When I saw this post, I figured that person was connected with you.

I would like an RR4 or older, but something fairly local.

travis++8-14-2013-12-31-4.jpg
 
Unbelievable!

I had to do a double-take, mine came with the same book. Judging by the Joplin CL text, I assumed the machine was a 2. Too bad we don't have the serial number from this one. That would be about a 4 hour hike for you, wouldn't it : )
 
That's why I thought you got it!

The one in Joplin sold. I thought about going to fetch it, but that's a 4 hr drive through the most boring and conservative area of Missouri.
 
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