Mystery components and cool ones

[Rob Strand]

Not sure those parts are off the shelf or someone made them - very common to DIY low valued resistors by windng resistance wire over other resistors.

They look to me like power supply remote sense resistors..

One of the possibles.  In the early days people made meter shunts to measure current.  Also, emitter resistors on the output stage of power amplifiers - the fact there's two resistors made me think of the last one.   However the fact they are burnt is more like power supplies and meter shunts.

[momo]

Oh I did not mention but I have maybe 30 of those.
I think the person who had this built hi-end audio tube amps.

[Rob Strand]

Oh I did not mention but I have maybe 30 of those.
I think the person who had this built hi-end audio tube amps.

That adds to the mystery. 

[antonis]

I think the person who had this built hi-end audio tube amps.

So, Emitter balast resistors idea is drifting apart..

[amptramp]

Chokes wound on resistors were commonly used in tube amplifiers and transmitters in the grid and plate circuits.  The purpose of the resistor was to damp out any tendency for resonance.  These items were used to prevent oscillation at high radio frequencies by adding a resistor to damp the oscillation and an inductor in parallel so the resistor wouldn't drop too much voltage due to the current through it.

If you had a transmitting tube like an 807 with a plate cap as an output, the several inches of wire between the tube and the output tuned circuit may create a tuned plate oscillator that could oscillate around 100 MHz even though the circuit was intended to operate at low frequencies like 7 MHz where the 40 metre band is..  These parasitic chokes were used to prevent this.  They were also used on large audio amplifiers because you still had connections that could oscillate at radio frequencies even though these oscillations were unintended.

These devices were so commonly used in radio transmitters that you could buy them as assembled units - you didn't have to buy a resistor and wind your own.

[momo]

Thats why I post these things is to learn cool stuff. Thanks for the info.

[momo]

Finally got to sort the 1/2 watt , or 1 watt? resistors, not sure.
I have never seen black ones like that....

[momo]

I can't find any info on this transformer either.
Does not show up on the Hammond website.

[Rob Strand]

I can't find any info on this transformer either.
Does not show up on the Hammond website.

There's a *very* good chance it's a 600 ohm to 600 ohm audio transformer.  Possibly with some tapped windings.

Measure the resistances across the terminals:   
- pin 1 to 2, 3, 4, .. etc, then,
- pin 2 to 3,  4, 5

etc.

You might see resistances in the order of 20 to 30 ohm (60 ohms max).
If you see different it might be for different impedances.

I just searched for hammond 600 ohm transformer and got this.
Looks like a very similar design although

https://www.ebay.com.au/itm/234757467908?chn=ps&norover=1&mkevt=1&mkrid=705-159824-816807-4&mkcid=2&mkscid=101&itemid=234757467908&targetid=4585307092966486&device=c&mktype=&googleloc=&poi=&campaignid=431353848&mkgroupid=1307319748402955&rlsatarget=pla-4585307092966486&abcId=9301943&merchantid=136820&msclkid=57f191b12ce81ac4e2b5f5e2916cfd90

600 ohm to 600 ohm
100mW
20Hz to 20kHz  +/- 0.5dB
Less than  0.2% distortion.

[Rob Strand]

Well look at this from Hammond 1965 catalog,

http://www.hammondmfg.com/hist.htm

Page 6, type 960,
http://www.hammondmfg.com/pdf/Catalog%2065.pdf

[mozz]

I'd measure those resistors before using them, chances are they are over spec/tolerance on the high side.

[momo]

I'd measure those resistors before using them, chances are they are over spec/tolerance on the high side.

They are, I just put a ballpark testing a few,(I'm not very good detecting the colours).
I test everything I use so yea, I just pick the closest one.

[momo]

So google is useless if you don't know what your looking for!
Thanks Rob for your efforts on the research.
So it seems these 960's are output transformers matching the plate to the voice coil.
If it's the case then these are Hi-Fi transfos .

[Rob Strand]

So google is useless if you don't know what your looking for!
Thanks Rob for your efforts on the research.
So it seems these 960's are output transformers matching the plate to the voice coil.
If it's the case then these are Hi-Fi transfos .

Yes, 10W.  The notes in the catalog say to keep the DC balanced through each winding.

Not a common construction for an output transformer.  If I had to bet I would have gone with the 600 ohm
over an output transformer. Goes to show you can only guess so far.   Things are what they are.

[bluelagoon]

Gold Bar Capacitors, all numbers correspond with Pico Farads pF all still very tight within tolerance. the ones marked L somehow seem to denote 100pF

[Rob Strand]

Gold Bar Capacitors, all numbers correspond with Pico Farads pF all still very tight within tolerance. the ones marked L somehow seem to denote 100pF

Never seen those before.    I wonder what they can claim.  Tight tolerance.  Maybe stability (with temperature/time)?

(If L = 100pF then L comes from Roman Numerals.)

[bluelagoon]

Hi Rob, What i meant by tight within tolerance, was that even after likely well on 60 years or more they are still very close from as little as 1% to no more than 5% away from there rated number specs, at least the larger pF ones were.
Does L in Roman numerals mean 100? I thought it was C was 100?
Just checked that and yes C is still 100 from Rome, but L is actually 50, so in that regard, means these smaller value ones have drifted to
just over twice there rated pF value, spose they could count now as 100pF

[Rob Strand]

Hi Rob, What i meant by tight within tolerance, was that even after likely well on 60 years or more they are still very close from as little as 1% to no more than 5% away from there rated number specs, at least the larger pF ones were.

Pretty cool.  I wonder what they are from?

Does L in Roman numerals mean 100? I thought it was C was 100?
Just checked that and yes C is still 100 from Rome, but L is actually 50, so in that regard, means these smaller value ones have drifted to
just over twice there rated pF value, spose they could count now as 100pF

Yes, you are right.  (My heads not screwed on this week.)

[bluelagoon]

I did get these and a lot of other vintage components from an elderly retired vacuum tube CRT screen TV repairman, who also did vintage tube radios, so guess they came from that type equipment.

[duck_arse]

ham?