Time Electonics - Model 505 D.C Currrent Source

[Mr Eastwood]

Another Ebay low cost ex-mod purchase to add to the collection;  not too much to say other the unit looks good inside, no sign of any previous battery leaks.  Very nice item, I look forward to playing around with it on the bench.


[edit]
Link to a similar unit https://www.vintage-radio.net/forum/showthread.php?t=126780

[SeanB]

Very nice looking unit.

[ProBang2]

That is mean!   

Somehow it would be interesting to me, what the connected DMM shows...   

[Mr Eastwood]

That is mean!      Somehow it would be interesting to me, what the connected DMM shows...   

ProBang, I know that was really mean of me,  it was wrong wasn't it!   SO to try make it up to you I have posted some readings; 

the dial settings were set at: 4000 on .9999, 9.999 and 99.99 mA ranges respectively matching the images (left to right) or (top to bottom)

the meters used were:  idm 305 (1), idm 305 (2), idm 305 (3) and solartron 7150 (1) and solartron 7150 (2)

[ProBang2]

Hello!

Thank you for your efforts. It seems, the 505 DC current source is still pretty well in spec. 
(Maybe a little on the low side, but that could easily caused by the resistance of the test leads and the current shunts. The tolerances of the DMMīs are added anyways.)

So I have to say: I am really very impressed from this device. 

When was the current source built? My guess would be: Pretty much 40 years ago.
And works still fine...
I donīt expect such a long lifetime from the items, nowadays produced.

BTW: Regarding the readings from your second Solartron 7150: 0.29 mA, 3.88 mA.
Is there sadly a problem in the lower current range? 

Greetings

[Mr Eastwood]

Hi,   

"When was the current source built? My guess would be: Pretty much 40 years ago."
Quite possibly, they used the same case design I think for a good few years.

"BTW: Regarding the readings from your second Solartron 7150: 0.29 mA, 3.88 mA.
Is there sadly a problem in the lower current range? "

VERY good point!  looking at the service manual there is only 1 range for current and that is 2A;  so a big jump like that looked quite odd;  so i left both meters on for about 5 hrs; then re-did the readings for #1 and #2;  but this time both meters were NULL'd and then i switched on the FILTER.

Basically much better readings.

[ProBang2]

Happy to see the second unit works fine, too!