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 A battery set with 3 I.F Cans ! Why?
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 Return to top of page · Post #: 1 · Written at 10:32:26 PM on 17 May 2023.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 2161

The valve line up is 1T4 , 1T4, 1S5, 1Q5 and 1R5 . The Brand name is Cavalier. Yes it has what appears to be 3 I.F cans. Why would this be.

Cavalier valve radio
Cavalier valve radio
Cavalier valve radio


 
 Return to top of page · Post #: 2 · Written at 12:15:30 AM on 18 May 2023.
Robbbert's avatar
 Location: Hill Top, NSW
 Member since 18 September 2015
 Member #: 1801
 Postcount: 2039

You sure about the "1Q5"? It would more likely be a 3V4 or 3S4.


 
 Return to top of page · Post #: 3 · Written at 6:41:30 AM on 18 May 2023.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 2161

Robbert its written on the Chassis and its not a miniature socket.
Was told in another forum that the other can maybe the oscillator coil even though it looks identical to a I.F can.


 
 Return to top of page · Post #: 4 · Written at 10:30:50 AM on 18 May 2023.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5303

I have only ever fixed one Roberts and it featured on Silicon Chip. I should still have data. Roberts is English and the one I got had spent most of its life in South Africa. 3 IF cans is odd but I have seen it, however, technically one was a band pass filter.

Might need to do a little more exploring.


 
 Return to top of page · Post #: 5 · Written at 4:55:58 PM on 18 May 2023.
Robbbert's avatar
 Location: Hill Top, NSW
 Member since 18 September 2015
 Member #: 1801
 Postcount: 2039

1Q5GT, interesting. An output valve capable of a massive 1/4 watt.

Of the 3 cans, I would assume the extra could be between the RF amp 1T4 and the mixer 1R5.

My guess of valve functions:

1T4 - RF amp
1R5 - mixer
1T4 - IF amp
1S5 - detector and AF amp
1Q5 - audio output

Personally I've found the 1R5 to be quite unreliable - when I tested my collection of them, half didn't work.

You didn't mention the existence of an AC/DC converter - I assume then it either doesn't have one, or it uses a solid-state rectifier. Many radios used a 6V4.

I suppose it's possible there's 2 IF stages instead of the RF stage. That would also account for the extra can.


 
 Return to top of page · Post #: 6 · Written at 5:21:59 PM on 18 May 2023.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 2161

Robbert its straight battery! No AC
Marcc this one is a Australian set with Australian Stations and the knobs are Airzone..


 
 Return to top of page · Post #: 7 · Written at 5:50:01 PM on 18 May 2023.
DangerousDave's Gravatar
 Location: Toongabbie, VIC
 Member since 1 September 2020
 Member #: 2438
 Postcount: 131

What is so odd about 2 IF stages utilising the 2x 1T4?


 
 Return to top of page · Post #: 8 · Written at 6:00:31 PM on 18 May 2023.
DangerousDave's Gravatar
 Location: Toongabbie, VIC
 Member since 1 September 2020
 Member #: 2438
 Postcount: 131

Having two IF stages (3x IF transformers) will give a radio both more gain and better selectivity than a combined single IF stage and a single RF stage. (utilising the same valve count) In comparison a receiver with an RF stage will give much better image rejection.


 
 Return to top of page · Post #: 9 · Written at 8:38:07 PM on 18 May 2023.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 2405

Yes Dave your are 100% right. Many early battery sets using both the octal and the 7 pin 1.4v series had 2 stages of IF.

You do get a lot more sensitivity for your money that way.

Reason for the 1Q5? Very common immediate post WW2 because they were available for 2/6d (25 cents to you!) as WW2 surplus. I have a Philips radio that has that lineup.

Would have to be battery only because the 1Q5 can't have its two filaments connected in series - you need the somewhat rare 3Q5 for that.


 
 Return to top of page · Post #: 10 · Written at 9:26:58 PM on 18 May 2023.
DangerousDave's Gravatar
 Location: Toongabbie, VIC
 Member since 1 September 2020
 Member #: 2438
 Postcount: 131

Hi Ian, yes it seemed to be a reasonably common combination for battery sets in the late 40’s with STC and Krielser having examples. Philips and Mullard utilised this line up of 2x IF stages with quite a number of their Battery set models through this period. I have never given it much thought to the use of the 1Q5 but this makes perfect sense.


 
 Return to top of page · Post #: 11 · Written at 10:27:04 PM on 18 May 2023.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5303

It would not be uncommon to have original Airzone knobs as badge engineering was rife and Airzone in various forms & affiliations manufactured a huge amount of radios aside from their own.

The Roberts comment was for a specific model and it was built in UK. It is plausible the thing was made under licence or parts of it were imported albeit that the English Roberts has its European numbered valves.

Marc


 
 Return to top of page · Post #: 12 · Written at 10:43:58 PM on 18 May 2023.
Brad's avatar
 Administrator
 Location: Naremburn, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 7342

Photos uploaded.


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

 
 Return to top of page · Post #: 13 · Written at 2:43:00 PM on 19 May 2023.
Gandhn's Gravatar
 Location: Cameron Park, NSW
 Member since 5 November 2010
 Member #: 770
 Postcount: 399

From the physical position of the 2 X 1T4 next to each other, it would have to be 2 X IF stages, wouldn't it?
Harold


 
 Return to top of page · Post #: 14 · Written at 4:10:48 PM on 19 May 2023.
Robbbert's avatar
 Location: Hill Top, NSW
 Member since 18 September 2015
 Member #: 1801
 Postcount: 2039

I can't tell from those photos what's in the top two positions.

When I made my comment earlier, it hadn't occurred to me that there could be 2 IF stages until I was almost finished writing, that's why it appears as a postscript.

The only battery sets I've seen (or at least recall what the arrangement was) had a RF stage.

But if 2 IF stages was a common thing, then I've learned something, which is what we're here for, right?


 
 Return to top of page · Post #: 15 · Written at 5:13:21 PM on 19 May 2023.
DangerousDave's Gravatar
 Location: Toongabbie, VIC
 Member since 1 September 2020
 Member #: 2438
 Postcount: 131

It’s fair to say that most “portable” type battery sets made through this period that included an extra stage usually had this as a RF amp in front.
I guess with most things considered, portables generally relied on the internal antenna employed by the radio in which a tuned RF stage would be more beneficial than an additional IF stage. This was a more expensive design option though.


 
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