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  ·  Glossary  ·  Outside Links  ·  Policies  ·  Services Directory  ·  Safety Warnings  ·  Tutorials

Tech Talk

Forum home - Go back to Tech talk

 Essanay Bantam 80 1937
« Back · 1 · 2 · Next »
 Return to top of page · Post #: 16 · Written at 8:15:34 AM on 23 January 2020.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 2372

Carl, if you want to replace that plastic dial window, consider using a "watch glass".

This is a clear glass shallow dome available from laboratory suppliers in packs of 5 or 10 for very little money. EG:

https://www.labdirect.com.au/glassware/watch-glasses/

The ones I bought were slightly larger than that EFCO bezel, it can nevertheless be glued behind it.
Run a bead of contact adhesive around the bakelite lip inside the case. Position the glass so glue transfers to it, then remove the glass. Let it dry for about half an hour, not just tacky, completely touch dry. Then press the glass into place again. Adhesion is instant and very strong.

It really looks the part and is completely clear, permanent and scratch-proof.


 
 Return to top of page · Post #: 17 · Written at 3:25:14 AM on 24 January 2020.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 2157

STC830 thankyou for the schematic . We were able to use it to help align this little set. It was way out of alignment.


 
 Return to top of page · Post #: 18 · Written at 8:14:33 AM on 24 January 2020.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 1256

No worries.
How does it go without AGC?


 
 Return to top of page · Post #: 19 · Written at 9:23:53 AM on 24 January 2020.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5257

Their in lays a warning: The majority of manufacturers recommend that you realign if parts have been changed in the RF: Coils do drift in alignment as well and Monkeys like to tamper if it breaks down.

Alignment is the greatest cause of "Deaf" sets, This is why the first job on getting it running here is align.

Rather than modify and make it what it wasn't 68pF in series with the antenna should sort out strong stations. Many sets with no AGC / AVC used a DX switch to do similar.

Marc


 
 Return to top of page · Post #: 20 · Written at 2:14:43 PM on 24 January 2020.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 1256

"Rather than modify and make it what it wasn't ......"

I agree and I have always tried to maintain originality consistent with safety and reliability, especially if the set is leaving my hands.

I understand from reading in the past, probably in Radio Waves, that control of volume using simultaneous control of signal strength and valve bias is about as effective a control of volume in the face of greatly varying signal strength, that you can get without AGC / AVC in a small cheap set that needs to be simple to operate.

I am curious about how good that control is in fact. Could it be given to old Aunt Flo without blasting her ears going from weak to strong stations?


 
 Return to top of page · Post #: 21 · Written at 4:57:21 PM on 24 January 2020.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 2372

As a kid growing up in the 50s my family had an STC mantle radio without AGC and the volume was always jumping around as things in the house were switched on or off. Very annoying.

First chance I got I put AGC in it.

Sure authenticity is important, but if you want to actually USE the thing a certain amount of civilisation is needed.

I would also modify an anode bend detector radio, hiding the 1N4148 diode in the IF can. 20% THD isn't something up with which I would put! Modern AM transmitters modulate to 100%, it helps get over the background noise. Anode Bend detectors can't handle this without very unpleasant distortion.


 
 Return to top of page · Post #: 22 · Written at 5:49:08 PM on 24 January 2020.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5257

My main concern with that one is getting enough voltage and the cathode circuit via the antenna coil may need work. May prove to cause undesirable effects on band width as well.

Marc


 
 Return to top of page · Post #: 23 · Written at 10:51:23 PM on 24 January 2020.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 2157

Ian I agree with your philophosy about authenticity and civilisation . I have a stack of 1.5k on/off switches here which was ideal for this set as it had no on/off switch and the volume pott was 1.5k. It added a bit of safety and kept the original look. I have a EMMCO jewel here which has the same setup, ie volume control in the antenna circuit and no agc but the volume control has a lot more turn tobit and just seems to go on and on. It works very well indeed.


 
 Return to top of page · Post #: 24 · Written at 9:43:05 AM on 25 January 2020.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5257

The thing with this one is that if it had IF one, you could get delayed AGC off of the plate of it.

Marc


 
 Return to top of page · Post #: 25 · Written at 10:20:09 PM on 7 February 2020.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 2157

Finally got this little set completed. Have sent photos. Talk about a squeeze putting this together!

Essanay Valve Radio
Essanay Valve Radio


 
 Return to top of page · Post #: 26 · Written at 10:27:37 PM on 7 February 2020.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5257

Did you try a shoe horn?


 
 Return to top of page · Post #: 27 · Written at 2:32:03 AM on 8 February 2020.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 2157

No room for a shoe horn lol.


 
 Return to top of page · Post #: 28 · Written at 10:01:08 PM on 9 February 2020.
Brad's avatar
 Administrator
 Location: Naremburn, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 7305

Photos uploaded to Post 25.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

 
« Back · 1 · 2 · Next »
 You need to be a member to post comments on this forum.

Sign In

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