REVEALED! Riverside’s peculiar microwave oven

I’ve always been a little disappointed by the display of an early microwave oven in Riverside (Glasgow’s transport museum).

As seen in the pic below, it’s always on show with the lid closed, so it’s not possible to the interior, beneath the chrome.

That said, there’s no real mystery, as this type of microwave oven has been documented elsewhere, as summarised in the original post: Riverside’s peculiar microwave oven

Husqvarna Electronic Microwave Oven 1959

However, it’s always possible to ‘Do Better’, and my luck was in as was near Riverside recently, and popped in for a quick look.

Always surprisingly (or should I say disappointingly) busy, I’m grateful for my noise-cancelling earbuds, which help to tone down the sound of a thousand screaming kids which seems to fill the place nowadays.

Coming down the stairs at the back, I took a walk along the shop displays, and was rewarded with a view of this old microwave oven, in the OPEN position.

I’ve become slightly intrigued by this design, and wonder how effective it was.

A modern microwave oven has flat sides, and I’m guessing the dimensions of the aperture are designed to promote standing waves and resonance, to couple the maximum power from the magnetron, and avoid the waves just bouncing around in there and cancelling themselves out.

I’m not sure how this work using the shape seen here.

There’s an amusing episode of MythBusters from some years ago, where they thought they’d build a Mega Microwave, with FOUR magnetrons firing into the chamber.

As they built it, and fitted the magnetrons, I was surprised they didn’t take the operating frequency/wavelength into account, calculate the appropriate length, width, and height of the oven’s chamber, and position the magnetrons accordingly (for standing waves and reinforcement).

They were surprised, and mystified, when their Mega Oven not only didn’t work, and instantly incinerate anything placed inside, it didn’t work at all, and apparently didn’t produce ANY heating of the contents. This really was a surprise, as I’m usually impressed at their research, and level of attention paid to many of the myth they investigate and attempt to reproduce. In past episodes, they’ve often researched the reason for a failure, and revised their built to take that into account, but this time – nothing. They just scratched their heads, and were done with it.

I always wondered if there was ever a follow-up, or if anyone told them about their massive boo-boo.

Riverside’s peculiar microwave oven

Another pic I never used at the time I took it, this time from Riverside.

I’m not sure how many people visit museums and pay attention to displays that lie around the periphery, but it’s always worth taking a look at everything on offer. You never know what you might be missing.

In Riverside, the ground floor has a number of displays related to shops and services, with content ranging from toys, the cinema, garages, bike shops, and even pawnbroking.

Life was different in the past, and it wasn’t unusual to pawn items towards the end of a week, before the pay-packet was brought home by the breadwinner, and treasured possessions could be redeemed – until the end of the next week!

In Riverside’s pawn shop window there lies a very unusual item, one which most people will not recognise if they’ve only seen a present day version.

Looking distinctly modern for the day, and VERY science fictiony, is an early microwave oven.

It had me fooled the first time I saw it, mainly because I had been involved in high temperature testing, and for that we used shiny spherical electric furnaces to raise test subjects to over 1,000°C under tightly controlled conditions at their centre – this microwave oven looked very similar.

Husqvarna Electronic Microwave Oven 1959

Riverside’s description card for this device reads:

Husqvarna Microwave Oven Description

In the early 1950s, a microwave oven might have had a four-figure price tag, but by the end of that decade the price was dropping rapidly, and by the 1970s was around £200 and still falling quickly.

Before you start thinking that’s not so expensive, taking inflation into account, £200 in 1975 would be like £1,700 today.

There is some history of the microwave oven online, and it does date back to the 1945 thanks to the invention of the cavity magnetron, and a patent filed back then, for cooking, after an accidental discovery.

 Heating effect of a high-power microwave beam was discovered in 1945, completely by accident. Percy Spencer, who was a self-taught engineer from Howland, Maine and was an employee of Raytheon, worked on an active radar set when he noticed that a chocolate bar that he had in his pocket started to melt. He then tried an experiment with popcorn and then with an egg (which exploded). Spencer then created a high density electromagnetic field by feeding microwaves from a magnetron into a metal box from which they could not to escape. Temperature of a food placed in a box raised much faster that in open. Patent application for Spencer’s microwave cooking process was filed on October 8, 1945, by Raytheon and the first microwave oven was placed in Boston restaurant for testing. The first microwave oven usable by public was placed in Grand Central Terminal, in New York City, United States, in January 1947. It was in the form of the Speedy Weeny vending machine which dispensed hot dogs.

See History of Microwave Oven

There’s another one – in a Swedish museum

The delay in finally getting around to using this pic turned out to be fortunate.

First time around I tried to find more information about the Husqvarna microwave, with little success.

Incidentally, Husqvarna is a Swedish company founded in 1689 to produce muskets, and has grown considerably since then. It has diversified, and is now a brand name with multiple companies. Notably, it is a brand name for home appliances manufactured by Electrolux.

Second time around I must have used better phrasing, and came up with a later version, this one on display in the  Tekniska museet – Stockholm, Sweden, and shared in a Wikipedia media pic.

The description of the pic notes: “Cupol microwave oven, designed in 1969 by Carl-Arne Breger, Husqvarna, c. 1973“.

There’s also a small descriptive panel just visible at the bottom right of the oven, although the bottom is missing.

Swedish Cupol Description

Enlarged and translated, this says:

Microwave oven Cupol, Husqvarna This microwave oven is one of the first to be manufactured in Sweden. It was designed in 1969 by Carl-Ame Breger, who also designed the plastic packaging for the BigPack ice cream, the Rex children’s bicycle saddle and the Diavox phone. The microwave has…

Unfortunately, that’s all there is.

There’s no clue as to why there is a Mars bar sitting in the middle of the oven.

THAT’s going to make a bit of a mess if somebody turns the oven on.

Husqvarna Cupol Microwave Oven 1969

Despite a separation of some ten years between the two (if the information given is accurate), both items have a distinctly hand made appearance if looked at closely.

The labelling of the controls looks very ‘home-made’, and has more of the appearance of a prototype or design model than a production item intended for sale to the general public.

The figures on the example in Riverside don’t really match in terms of size and font, and the word ‘STOP’ is actually spelt as ‘STOPP’.

Both of these early examples appear to be missing one very important item now considered essential for a microwave oven…

Neither has a timer!