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 STC Model 205 (Jelly Mould)
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 Return to top of page · Post #: 1 · Written at 7:13:24 PM on 12 July 2017.
Captgogo's Gravatar
 Location: Sydney, NSW
 Member since 22 May 2017
 Member #: 2114
 Postcount: 120

Hi Guys
Can any of you confirm for me if the orginal STC Model 205 came with a Glass Dial Face which is curved or was it a hard plastic.
I am looking to buy one, which has a plastic Dial Face.

Thanks
George


 
 Return to top of page · Post #: 2 · Written at 8:24:42 PM on 12 July 2017.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1575

Mine has a plastic cover. what are you calling the dial face , is it the cover? Actually my Broadcast model also has a plastic cover.


 
 Return to top of page · Post #: 3 · Written at 8:33:28 AM on 13 July 2017.
Captgogo's Gravatar
 Location: Sydney, NSW
 Member since 22 May 2017
 Member #: 2114
 Postcount: 120

I am referring to the clear curved cover over the dial. I also am now aware that there are two models the 205 and B105, the 205 had the Broadcast/MW and four knobs. I assume the Curved Clear Dial cover on both is made of the same material. I belive both these were made around 1946-48. Any other info on this radio that anyone has will be appreciated and if anyone wants to sell theirs send me am email.
Cheers George


 
 Return to top of page · Post #: 4 · Written at 9:49:10 AM on 13 July 2017.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 1911

Cut To Size Plastics can cut you one from 0.5mm clear lexan which will flex to fit the curve.


 
 Return to top of page · Post #: 5 · Written at 7:18:13 AM on 14 July 2017.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4347

Many of those where it was curved were Nitro-cellulose plastic, which was identifiable by its tendency to go brown; That being caused by that particular plastic starting to decompose from day one. Not that plastics of the fifties used in coil formers & such things are not doing the same, differently & I have seen a few decomposing. Wood, Ceramic & Bakelite are the survivors, in early stuff.

I cannot recall any, in several hundred radio's that have come here, seeing curved glass in any.


 
 Return to top of page · Post #: 6 · Written at 3:29:49 PM on 19 July 2017.
Captgogo's Gravatar
 Location: Sydney, NSW
 Member since 22 May 2017
 Member #: 2114
 Postcount: 120

So I have now another radio to restore, though I was looking at the 205, I ended up with the STC D105, I really like the look of the "Jelly Mould" as it is called, but it looks like a modification has been made, though I have not taken it out of the cabinet as yet, on the back is a threw way toggle switch where the the knob should be. Can anyone conform what the knob on the rear on the orginal would have been for, was it the on/off switch? I assume the knobs on each side is volume and the other is definitely for tuning.


 
 Return to top of page · Post #: 7 · Written at 4:18:00 PM on 19 July 2017.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6013

There's a photo of the rear of the B105 chassis here:

http://www.radiomuseum.org/images/radio/standard_telephones/b105_1633357.jpg

The schematic shows a 0.5M tone control, so I guess that's it on the rear. There's no mention of an on/off switch, although it was common back in the day to have one mounted on the tone control.


 
 Return to top of page · Post #: 8 · Written at 7:10:10 PM on 19 July 2017.
Captgogo's Gravatar
 Location: Sydney, NSW
 Member since 22 May 2017
 Member #: 2114
 Postcount: 120

Thanks GTC, I did go Initially to Radiomuseum but only looked at the D105 which is what this radio is labelled as on the underside, with the 6V6G crossed out and replaced with a 6F6G valve I assume done at the factory, I am not sure exactly what the other difference is to the B105 and the photo on Radiomuseum of the D105 is only a front view. I could not see an on/off switch on the D105 schematic either, so it must be a previous owner mod.


 
 Return to top of page · Post #: 9 · Written at 9:22:54 PM on 19 July 2017.
Robbbert's avatar
 Location: Sydney, NSW
 Member since 18 September 2015
 Member #: 1801
 Postcount: 1381

Someone probably didn't have a spare 6V6G and threw in the 6F6G in instead, as they have the same connections.


 
 Return to top of page · Post #: 10 · Written at 9:58:22 PM on 19 July 2017.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1575

Neither of the jellymoulds had on / off switches.


 
 Return to top of page · Post #: 11 · Written at 12:16:21 AM on 20 July 2017.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4347

The bias and the speaker transformer, (the latter being more difficult to identify) may be the clues as to what went on there. The 6V6 will have around - 4V less . 250V than 6F6 on grid one.

6F6 (250V DC) is quoted with a 7K primary (Rk 410 Ohms): 6V6, 5K. (Rk 250 -270 Ohms).

Strange things can happen to sets in their lifetime. I have just won a HMV that I believe is E43F. It has been got at and it has half a dial glass. So far I have tossed about four resistors, and one wrong electrolytic. It is patently obvious that this is "a whatever was on hand at the time job.

I will change the other filter caps, but have run out of them. Like yours wrong OP valve: This had EL84 (6BQ5). That is not one I have ever seen in a HMV. It would never run as on both of these valves (HMV normally 6M5) pin two is grid one: Not pin 1. The grid resistor was high & it was the wrong value coupling cap? Both back bias resistors are high in value.

And you wonder why I advocate looking before powering.


 
 Return to top of page · Post #: 12 · Written at 8:17:21 AM on 20 July 2017.
Captgogo's Gravatar
 Location: Sydney, NSW
 Member since 22 May 2017
 Member #: 2114
 Postcount: 120

Hi Marc,
Thanks for that, I will look carefully at the voltages and circuits, Interestingly if you look at the notes on the schematics of the D105 & E105, they mention the 6F6 for the E105, but the schematic is for both D & E versions. On the bottom of mine it is labelled a D105 but has a printed (not hand written) on the valve line up diagram the 6F6 but it is in red and smaller font with a line through the 6V6, this leads me to believe it may have left the factory with a 6F6.
Agree with Carl though the toggle switch on the rear is a modification. When I get some time it will remove this interesting cabinet had have a look at what has been done.
I am also keen to pick up a STC 205 when one comes up for sale, anyone selling?


 
 Return to top of page · Post #: 13 · Written at 10:07:46 AM on 20 July 2017.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4347

There are often factory mods and around war time they were common. One HMV changed to a Philips valve as WD scarpered off with all of the 6B8"s. If You look carefully, there was at that period, a reversion to 6pin valves after actually starting to change to octal.

I did have one set that a collector still has, where the RF was one years model the the Audio the others? You do have to be a wake up to some of the things caused by supply, demand, & the bean counters in the supply department.

With the most common plastic "Little Nippers" there is in the early model two 22K resistors in parallel feeding RF screens. Somehow that became a single 10K. Never should that be left unchecked: 1,000 Ohms does make a difference. If the voltage is correct, or slightly high, I squared R, tells us that that resistor has to be more than 1Watt. This does not appear to be the case & in around ten of them I have replaced it with 2Watt or two 22K 1W in parallel as they have slowly cooked.

In any set that appears to be, or has been tampered with, one never powers it without an assessment. One never powers any unknown set with out an assessment to see if it has been tampered with, or is safe to power. That also applies to battery sets.

Marc


 
 Return to top of page · Post #: 14 · Written at 2:27:02 PM on 12 August 2017.
Sirwin's avatar
 Location: QLD
 Member since 10 April 2009
 Member #: 465
 Postcount: 104

I have a B105 and a D105 here. The former has a glass transparency, the other is plastic, presumably celluloid.
Interestingly, the B105, which is supposed to use a 6AG6G had a 6V6GT plugged in instead. Result; burned out power transformer. Sad Luckily I had a spare. What I did not have was a 6AG6G that would fit. I did have a couple, but the 6AG6G came in two sizes, and only the smaller size will fit, and I only had the larger size. I ended up retaining the 6V6GT but altering the bias so that it drew the same current as the original 6AG6G. I have come across this three or four times: a high slope valve being replaced by a lower slope valve resulting in excessive current and overheated transformers.

Cheers, Stuart


 
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