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 STC 528
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 Return to top of page · Post #: 1 · Written at 10:27:06 AM on 1 June 2023.
Sandbar40's Gravatar
 Location: Tauranga, NZ
 Member since 13 July 2010
 Member #: 695
 Postcount: 35

Looking for a clear schematic and other info for this. 1939. Apparently it's in Vol 3 of the Official Radio Service Manual.
Anybody restore one?


 
 Return to top of page · Post #: 2 · Written at 2:20:46 PM on 1 June 2023.
Irext's avatar
 Location: Werribee South, VIC
 Member since 30 September 2016
 Member #: 1981
 Postcount: 482

Have you tried Radiomuseum.org.
I recently downloaded a circuit for an STC 536 I'm restoring.
It's not perfect but gets you in the ballpark.


 
 Return to top of page · Post #: 3 · Written at 5:45:58 PM on 1 June 2023.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 1284

Already have this on file for some reason - will send to your email.


 
 Return to top of page · Post #: 4 · Written at 6:13:05 PM on 1 June 2023.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 1284

Sorry, sent you a 536 circuit - will scan 528 for you later this evening.


 
 Return to top of page · Post #: 5 · Written at 7:53:35 PM on 1 June 2023.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 1284

STC 528 circuit sent.


 
 Return to top of page · Post #: 6 · Written at 12:14:38 PM on 13 June 2023.
Sandbar40's Gravatar
 Location: Tauranga, NZ
 Member since 13 July 2010
 Member #: 695
 Postcount: 35

Update on the 528. Got working and set IF's to 450 kHz as shown on the schematic, set sig gen to 1500kHz and adjusted osc. trimmer to receive at 1500 on dial. (after setting dial pointer to equal positions at each end of the scale).Adjusted the padder at about 600 kHz for strongest response. set the ant. trimmer for best at 1500.
However, the padder was screwed right in and the ant. trimmer right out but screwing it in at a station mid scale gave a marked improvement there (tracking error?) Performance was reasonable.
Someone had pencilled 456 on the IF cans, so I decided to re-align at this frequency. Trimmer and padder positions were now not so extreme and performance better, so left at that. Is the schematic wrong or was a change made by STC?


 
 Return to top of page · Post #: 7 · Written at 3:51:18 PM on 13 June 2023.
Irext's avatar
 Location: Werribee South, VIC
 Member since 30 September 2016
 Member #: 1981
 Postcount: 482

I'm currently working on a STC 536B which has an I.F. of 455kHz whereas the 536A is 450kHz.
Maybe there's two versions of yours with different I.F. frequencies.?


 
 Return to top of page · Post #: 8 · Written at 2:12:43 PM on 19 June 2023.
Sandbar40's Gravatar
 Location: Tauranga, NZ
 Member since 13 July 2010
 Member #: 695
 Postcount: 35

Can anyone tell/show me what knobs STC would have used on the '528' ? Did they use more than one type?


 
 Return to top of page · Post #: 9 · Written at 9:04:11 PM on 19 June 2023.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6720

Can anyone tell/show me what knobs STC would have used on the '528' ?

https://www.radiomuseum.org/r/stcaus_528e_ch_528.html

Did they use more than one type?

Can't say.


 
 Return to top of page · Post #: 10 · Written at 9:31:40 AM on 20 June 2023.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 1284

I see that you are a New Zealander. Is your radio of NZ build with the circular transfer/sticker on the back? If that is the case it is possible that different knobs were used than shown on the photograph of a STC528 at Radiomuseum.

I have looked at Steve Savel's STCs of 1930-1942 book and he does not have a photo of a 528 and I can't work out from the text what knob it should have. He does however have photos of the knob styles used in that period, and the Radiomuseum item knobs are one of that group.

While he does not have a photograph of a radio labelled STC528, he does have a photo of a radio labelled STC504 which has 4 domed knobs different to those of the Radiomuseum example (3 stripes across the centre) and is dualwave in an upright cabinet. It is similar to that shown in Radiomuseum as a 528, except for a slight variation in the veneer stripes. HOWEVER, Silicon Chip published an article on the 504 several years ago and that had 3 domed knobs in a horizontal tabletop, MW only. So there is a question about the accuracy of Steve's book in this particular.

I also have his video which I will have a look at.

If you can contact Stuart (not Steve!) Irwin who submitted the Radiomuseum contribution on the 528, it might be your best bet.


 
 Return to top of page · Post #: 11 · Written at 9:46:02 AM on 20 June 2023.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 2161

STC830
I think Steve Irwin might not be with us any more LOL. But Sirwin is a member of this forum LOL as in Stuart Irwin and not the wildlife adventurer LOL.


 
 Return to top of page · Post #: 12 · Written at 9:47:14 AM on 20 June 2023.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 1284

Also search STC 528 on Facebook for Steve Milliken's example - this has domed knobs. An upright cabinet with 4 knobs, dualwave.


 
 Return to top of page · Post #: 13 · Written at 9:50:01 AM on 20 June 2023.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 1284

Carl, Stuart - sorry slip of the typing fingers there! Will edit that out.


 
 Return to top of page · Post #: 14 · Written at 2:07:44 PM on 20 June 2023.
Sandbar40's Gravatar
 Location: Tauranga, NZ
 Member since 13 July 2010
 Member #: 695
 Postcount: 35

Thanks for your inputs. The set is currently being restored as seen in the photos sent to Brad. The knobs appear correct for 1938 -9 as shown in Steve Saville's book. The set must have come from Aus.as shown by the Cabinet makers label.
Unfortunately the original speaker is mostly missing. The field coil section and output trans the only parts left, and were hooked to a modern PM speaker.Both the coil and trans were ok.

STC 528 valve radio
STC 528 valve radio
STC 528 valve radio
STC 528 valve radio


 
 Return to top of page · Post #: 15 · Written at 8:14:49 PM on 21 June 2023.
Brad's avatar
 Administrator
 Location: Naremburn, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 7342

Photos uploaded to Post 14.


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

 
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