Beauty of old electrical and measuring things, etc.

[dlgoff]

If the crystal frequency was too low you polished the plate to reduce the mass and so raise the frequency. If you went too far, you use the pencil on the entire surface, that increased the mass of the crystal and so took the frequency back to where you should have stopped polishing earlier.

Oh yea. I remember now about polishing. I think my mentor used the pencil eraser for that.

 

[dlgoff]

Vacuum leaks are a pain in the butt. So I picked up a couple vacuum gauge beauties that helped me find those leaks. With a good vacuum now, I just tried evaporated Aluminum on a glass slide. Here are the gauges and some Aluminum reflections.

 

[jim hardy]

Beautiful work, dlgoff !

 

[berkeman]

How big is that sheet in the bottom pic? It looks giant!

 

[dlgoff]

How big is that sheet in the bottom pic? It looks giant!

It's a 1" x 3" glass slide.

 

[dlgoff]

Beautiful work, dlgoff !

Thanks Jim.

 

[berkeman]

It's a 1" x 3" glass slide.

Oh, you're holding it up well above the grass. I thought it was laying on the grass. Big difference...

 

[dlgoff]

Oh, you're holding it up well above the grass. I thought it was laying on the grass. Big difference...

Yea. I'm holding the slide. Here's a couple more shots.

 

[dlgoff]

I've done a little updating of my vacuum deposition system. I needed a better vacuum in order to get cleaner depositions, so I added a rotary vacuum pump. I was also having a gauge tube problem because of a ground loop, so I earthed the piping and gauge controllers to a outside Earth grounding rod. Now I'm getting really low and stable pressure readings. Here are pictures of the system showing the new pump, ground wiring, and vacuum gauge readings.

I use the mechanical gauge (0 to 30 in Hg) as a reference for when to power up the foreline gauge (20 to 0 mm Hg) which serves as a reference for when to power up the vacuum chamber gauge (100 to 0 mTorr). Now I'm getting really nice Aluminum on glass slide depositions.

 

[dlgoff]

Here's a beauty you don't see every day. This rectangular loop antenna came out of a old tube type table top radio. It measures 14" X 10 1/2". I was a youngster when I took this out of a non repairable radio. I can't remember who made it.

The loops have spacers that lock into place with little wooden dowels. Three of these dowels were missing and I replaced with heat-shrink covered paper Q-tip shafts.

Here's a spacer with dowel.

Here how it was terminated with the lead-in wires.
edit: corrected typo

Any old times here ever seen one of these in a radio?

 

[jim hardy]

Any old times here ever seen one of these in a radio?

Not one nearly so robustly built.

Of what material are those slotted brackets made ?

 

[dlgoff]

Of what material are those slotted brackets made ?

I'm glad you asked that. I never looked into what the metal parts were made of. I had always thought the loops were made of a hard copper alloy. I just now used a magnet on the brackets. They're nonmagnetic and appear to be brass but on closer examination and testing with an ohm meter, they have infinite resistance and turn out to be made of "pressed paper" (and looks like the same find of paper used for the tubes you would find old radio coils wrapped on). Whereas the loops are really magnetic, so more than likely they're copper plated steel. The resistance of loops from end to end (measured on lead-ins) is 0.1 ohm. I searched the internet and only found one antenna that was similar. It was an http://www.ebay.com/itm/RADIO-LOOP-ANTENNA-Vintage-/112511382955?hash=item1a323375ab:gIUAAOSwIaFZKcHu and one can Buy it Now for US $99.00. Here's the picture of it.

 

[jim hardy]

Whereas the loops are really magnetic, so more than likely they're copper plated steel.

I wondered. The brackets do look like steel but that would short the turns ?
I guess the loops needn't be solid copper just a thick plating - at RF skin effect keeps current on the surface ?

 

[dlgoff]

... but that would short the turns ?

... making it more like a single loop antenna.

... just a thick plating - at RF skin effect keeps current on the surface ?

... thick enough depending a little on the RF's frequency.
from https://en.wikipedia.org/wiki/Skin_effect

 

[Joseph M. Zias]

How about Sensitive Research. They made some absolutely beautiful instruments in wood cases. I remember some of their true rms meters.
Ever hear of a "ballistic galvanometer". It was used to measure charge. Then there were those "leeds and Northrup" potentiometers to measure
temperatures with a thermocouple.

Oh, so many. Well, you have got me to thinking, now if you could just convince my wife that we should have a museum.

 

[dlgoff]

How about Sensitive Research. They made some absolutely beautiful instruments in wood cases. I remember some of their true rms meters.

Nice stuff indeed. Radiomuseum.org tell about some items made by the Sensitive Research Instrument Co. Here's are some images from their site.

Ever hear of a "ballistic galvanometer". It was used to measure charge.

Oh yea. They weren't made by Sensitive Research Instrument Co., but I used them in my University's physics labs. Very accurate way to measure charge.

...you have got me to thinking, now if you could just convince my wife that we should have a museum.

Yes you should have a museum. Show your wife this thread and tell her it's for the good of people's education and you want to be a part of that. It's been a learning experience for me and maybe for the both of you too.

BTW: Welcome to Physics Forums. Hope you'll stay here and post some good stuff.

 

[dlgoff]

Back on post #94 I showed an antenna that I built for the Narco Superhomer Nav receiver that's shown working in post # 98. Well now, I've found the actual Narco antenna for this radio. It's condition is a little rough but it should clean up okay. I'll post a couple pictures of it now and later some restored pictures. Then I'll replace the one I built with it and do some testing.

 

[dlgoff]

I have a lot of electron vacuum tubes in several cardboard boxes that I've been wanting to organize. So I bought some generic sleeved tube boxes and this old tube caddy. Part of one side is a little faded. It looks like part of the caddy had been exposed to light for a long time while the the other part was shaded.

 

[jim hardy]

Is there a similar thread in Mechanical Engineering for old machinery enthusiasts ?

 

[berkeman]

Zowie!

 

[OmCheeto]

I have a lot of electron vacuum tubes...]

Speaking of tubes, have you watched Star Trek's "The City on the Edge of Forever" recently?
I watched it last night, for the first time in many years.

Tubes galore!

Of course, I immediately thought of you, as the year was 1930, and I was curious if they had such tubes back then.
And Spock and Kirk were working for 15¢/hour for 10 hours/day, and rent was $2/week, which netted them $19/week.
I suppose I could just google what prices for tubes were back then, but I figure you might have the prices and dates stamped on some of your boxes.

 

[Averagesupernova]

I wonder what those tubes are filament wise. I would bet 12 volts. Notice there are 10 of them. Anyone see where I am going with this?
-
I guess they wouldn't need to be powered but for some reason I seem to recall thinking that they were in fact 'lit up'.

 

[jim hardy]

I wonder what those tubes are filament wise.

1930's? Indeed they resemble the #30 triodes in my antique radio from that era.
https://www.tubedepot.com/products/30-triode-st-shape

Before rural electrification when so many radios were battery powered lots of tubes had 1 to 2 volt filaments .

Junkshop nearby has a bushel basket of such tubes, I've resisted the temptation so far... but i probably ought to get all his 30's for my radio.

 

[Averagesupernova]

I have a 6 volt radio with 6 one volt filament tubes. I believe it is an Admiral. It needs an output transformer. I walk by it every day many times as it is in my hallway but it never occurred to me to post it in this thread. I'll have to get a pic.

 

[jim hardy]

It needs an output transformer.

Hammond still makes vintage audio transformers.

Do you know what impedance you need? I'll keep an eye peeled in local junkshop . vintage parts emporium .

 

[Averagesupernova]

Yep Hammond is the one I would go to.

 

[dlgoff]

Speaking of tubes, have you watched Star Trek's "The City on the Edge of Forever" recently?
I watched it last night, for the first time in many years. ...
... Of course, I immediately thought of you, as the year was 1930, and I was curious if they had such tubes back then. ...

I didn't see the episode last night but remember it. But yea. Up on post #139 I showed this cool find that was introduced in 1926.

It didn't have a filament as it's a gas tube that uses He. It still rectifies just fine with 120 Vac supplied to it.

 

[dlgoff]

Is there a similar thread in Mechanical Engineering for old machinery enthusiasts ?

I should get out more. I went over to the Mechanical Engineering forum to look for that similar thread but couldn't find it. However I did reply in a thread. If you should find that old machinery thread, please post a link for it here.

 

[dlgoff]

I have a 6 volt radio with 6 one volt filament tubes. I believe it is an Admiral. It needs an output transformer. I walk by it every day many times as it is in my hallway but it never occurred to me to post it in this thread. I'll have to get a pic.

Post a pic here and I'll look through my old goodies.

Hammond still makes vintage audio transformers.

Yep Hammond is the one I would go to.

You can get Hammond transformers from https://www.tubesandmore.com/. Here's their https://www.tubesandmore.com/products/transformers_chokes section.

 

[dlgoff]

Junkshop nearby has a bushel basket of such tubes, I've resisted the temptation so far... but i probably ought to get all his 30's for my radio.

You should get them.
I'm going to have to come see this "junkshop" and your "$0.30/lb junkyard".

 

[dlgoff]

These aren't beautiful old electrical devices but are beautiful in how they educate about devices.

The one on the left might interest @berkeman; a guide for taking the FCC element 4 exam for the Radiotelephone 1st Class Operator's License (Copyright 1958). The one of the right I got when I was 16 years old when Bell Telephone Laboratories, Inc. came to my town's summer fair; this guide was included in a Speech Synthesis kit (Copyright 1963).

 

[Averagesupernova]

Maybe not beautiful, but it is an electrical measuring thing. Notice the strange controls. Horizontal gain is certainly not something you see on many scopes.

 

[Averagesupernova]

Here are some pix of the radio that I had promised. From the looks of the cabinet, I need to dust. Haha. I am missing knobs, but I can make those. When I first acquired this radio I had to clean up the points in the vibrator. Those points are made of some of the hardest metal I have ever come across. I believe it had several bad tubes but I was able to find some. No bad capacitors which surprised me. The old timer I got the tubes from told me that there were certain brands of caps that just don't fail. Lucky for me, this set is full of them.

 

[Averagesupernova]

Although I have had this for years I have never used it. I don't have the probes with proper banana plug. If I do find some I doubt I will be attempting to measure 6 KV with it.

 

[Averagesupernova]

I just got this at an auction. An original. Not a cheap knock off. Haven't even had a chance to hang it up to try it. Interesting thing about this is that it came with a note describing it's history. It was originally in a school and given to an employee when clocks were replaced with electric. It got handed down to the employees child and from there given to a domestic employee (maid I suspect) . This party eventually became elderly and passed on. Their estate auction is where I scored the clock.