Welcome to Australia's only Vintage Radio and Television discussion forums. You are not logged in. Please log in below, apply for an account or retrieve your password.
Australian Vintage Radio Forums
  Home  ·  About Us  ·  Discussion Forums  ·  Services Directory  ·  Safety Warnings  ·  Tutorials

Workshops, Tools and Test Equipment

Forum home - Go back to Workshops, Tools and Test Equipment

 Coupling box & attenuator
« Back · 1 · Next »
 Return to top of page · Post #: 1 · Written at 12:01:19 AM on 5 November 2014.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 2693

This is from a request from a post re11-20 Kriesler.

Work Bench
Attenuator Circuit Diagram


There really is not much to this black box as it's main function is to direct traffic by taking the outputs from the sig gen & distributing them, to mainly BNC so that they can couple via coax so there is no signal radiating everywhere. Box is metal because of RF

The sig gen I have is a clone of an LSG-11 and I have one of those and it's original box. The main difference between the LSG & Clone is that one (LSG) has a 0.001 cap before its attenuator & that causes the counter grief, when it cannot get enough input. That is another reason for the black box.

It puts the counter before the cap that has to be added to the clone but on the LSG reduces the signal needed by the counter. It would be nice to have a generator with a counter that does not need some of this. But when the OP is around 0.1V, or more & you need micro volts & DC blocking, you need to attenuate.

The sig gen can be modulated from an external source but I found that as it outputs audio I could use that on the CRO's external sync to give a more stable picture. I prefer the CRO during alignment as it is more sensitive & can see distortion, as well as being a great signal tracer when things go pear shaped.

As will be seen RF in goes direct to the counter, which should not be calibrated with the "tone" on .. Then there is the DC blocking cap, followed by the next stage of attenuation. Note there are two outputs for that. viz BNC & banana plug.

Marc


 
 Return to top of page · Post #: 2 · Written at 7:56:49 PM on 5 November 2014.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 3919

Good idea. I like it.


 
 Return to top of page · Post #: 3 · Written at 10:16:01 PM on 5 November 2014.
DJ Oz's avatar
 Location: Central Coast, NSW
 Member since 18 April 2014
 Member #: 1554
 Postcount: 215

Very tidy Idea Marc Smile

Lot less clutter with leads and only what you need to be handling available
(apart from the fact no spurious signal floating about or reduced chances of)

When I was looking for a Sig Gen I did find a Fet based instrument as a project at a UK forum on Radio
Someone actually took that and added a frequency counter to it

https://yo4hhp.wordpress.com/2011/10/31/simple-rf-generator/.

(the original link to the design is off that page )

Id hardly call it a precision lab instrument as it stands but you just cant seem to buy these things here new any more (unless you want to pay through the nose for something thats way over kill)

What you could buy wasn't much more then that anyway from memory from the likes of DS etc

I did find a Loadstar that had a frequency counter rather then the dial..evolutionary step I suppose but the US price was like $300 plus and I think these are an obsolete item anyway

For valve gear I guess they dont have to be super high grade lab test gear just an accurate stable signal and with an accurate counter you got what you need, apart from how you might want to organize the Attenuation etc

I think some have modified the 324 with BNC so they can feed a counter

I like your Box idea thought, save modding equipment and brings things together neatly

Thanks Marc for sharing that Smile


 
 Return to top of page · Post #: 4 · Written at 11:14:08 PM on 5 November 2014.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 2693

Just for valve radio, alignment I would agree that if the generator is as I said, its good enough with the frequency counter calibrating it.

Do note that you can get & I have "double adapters for BNC. The Fluke counter is actually being fed by the thick wire going to the right. Apart from wire, that mostly uncapped duct is there to hold tweezers chopsticks, scissors, probes & anything else that fits in the grooves.

Happy its of use ..... can inspire others

Marc


 
 Return to top of page · Post #: 5 · Written at 11:21:17 PM on 5 November 2014.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 3919

that mostly uncapped duct is there to hold tweezers chopsticks, scissors, probes & anything else that fits in the grooves

I did note that useful idea, too.


 
 Return to top of page · Post #: 6 · Written at 12:34:25 PM on 6 November 2014.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 2693

Duct is handy: It keeps wire under control. There is wider fully capped duct on the shelf edge above the computers and it carries wires for printers, scanners, hubs, & corded rat, preventing them from being a massive tangle behind the screens & stress relieving wires from an engine that is actually on a shelf to keep it off the bench & above the floor dust.

Best to be misconstrued, radio quote of the day, when money was supposed to be mentioned; Claimed "Aluminium & Copper were flat"?

Marc


 
 Return to top of page · Post #: 7 · Written at 12:41:31 PM on 6 November 2014.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 4322

double adapters for BNC

Before Cat5/6 cable was commonplace, local area networks were half-duplex and wired in coaxial cable. These tees were quite plentiful because one was needed at each computer on the network. If an electronics shop isn't handy and you know an IT guru, he may have some lying around.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
Brad.

A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 8 · Written at 10:38:40 PM on 7 November 2014.
Art's Gravatar
 Art
 Location: Ipswich, QLD
 Member since 22 October 2013
 Member #: 1437
 Postcount: 886

Hi, Can you provide any info on the Siggen including year?
I will have an opportunity to buy the exact same one (upgrade from Leaser LSG-11).


 
 Return to top of page · Post #: 9 · Written at 11:27:09 PM on 7 November 2014.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 2693

Electrically, the only difference between the TED-20 & the LSG -11 is the output arrangement. Same valves same Colpitts oscillator.

I have the paperwork for both, which I made sure Kevin Chant also has. According to my paperwork I bought it new 22nd August 1975.

LSG is probably of the same vintage, I rescued it with original box at a car swap meet. It has been overhauled.

Marc


 
 Return to top of page · Post #: 10 · Written at 2:20:08 PM on 8 November 2014.
Art's Gravatar
 Art
 Location: Ipswich, QLD
 Member since 22 October 2013
 Member #: 1437
 Postcount: 886

Thanks, I thought it might be solid state. There's a massive ugly difference with regard to mine.
Image Link
I have cleaned it up and painted it, but it still won't be near as nice as the one on offer.


 
 Return to top of page · Post #: 11 · Written at 2:34:07 PM on 8 November 2014.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 2693

Yes, same as... I did repair & sort out the cable on this one as it was 2 wire & its a metal case. Compared to the photo & the fact this one was in its own box mine is an A category.

Marc


 
 Return to top of page · Post #: 12 · Written at 4:13:16 AM on 10 November 2014.
DJ Oz's avatar
 Location: Central Coast, NSW
 Member since 18 April 2014
 Member #: 1554
 Postcount: 215

Thanks Guys.

Yes Marc, agree I dont think they have to be up market just stable.

Keen eye GTC and another good idea Smile yes.

Yes I remember the BNC T's Brad and coax networks .

Art I went after one of then on LSG 11 EBay...little better I think then what I got .
The other does look good thought your right.

This was the unit I was waffling about above Loadstar 4162.
http://img.tarad.com/shop/p/po-recycle/img-lib/spd_20111006103454_b.jpg.

The evolution from this, I suppose.
http://www.testiran.com/images/products/big120060716055438.gif.

Company link.
http://www.lodestarelec.com/09-generator_counter.html.

I dont actually know if they still make them but not really all that cheap either.
Anyway Smile


 
 Return to top of page · Post #: 13 · Written at 10:36:56 PM on 10 November 2014.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 2693

I was going to post a reply earlier but the system fell over?

My general comment is that I would love one of those things, but unless you are doing stuff that needs lots of decimal places, or the high frequencies that the cheap jobs struggle with with the valves used and the under voltage, used by LSG & Mine. You really can't justify it if the unit is stable with a good wave form and you already have a frequency counter to set it with.

And again, to the point of pedantic ....... do not use modulated signal when calibrating with the counter. The one I use is a Fluke 1912A

Marc


 
« Back · 1 · Next »
 You need to be a member to post comments on this forum.

Time and Date

Official time: 15:07 (GMT + 10)
Sunday, 24th September, 2017.

Sign In

Username:
Password:
 Keep me logged in.
Do not tick box on a computer with public access.

Glossary

Vintage Radio and Television's glossary contains the definitions for dozens of words and phrases.

Outside links

On our free links page there are dozens of other vintage radio-related websites which may be of interest to you. Everything from national vintage radio clubs to personal and business websites is included. Outside links.