Single span receiver article in Practical Wireless - UK Vintage Radio Repair and Restoration Discussion Forum

saddlestone-man · 18th Dec 2017, 7:38 pm

Hello all.

A few months ago I started a thread about the single span superhet concept, whereby the long and medium wave bands are tuned as a single band. This was described in various 1934 issues of Wireless World.

A contributor suggested that a modern version was described in (maybe) a 1960s or 1970s issue of Practical Wireless. I wonder if anyone has a good collection of PW over these years might recall this article and let me know.

Thanks in advance for any help you can give me.

Best rgds. Stef.

Dave Moll · 18th Dec 2017, 7:57 pm

If anyone can narrow it down somewhat, I certainly have all the issues over that period. Unfortunately, I don't have the time to search through the 240 issues covering the two decades.

Trevor · 18th Dec 2017, 8:27 pm

Armstrong with their 626 receiver was a single span unit i.e. mw and long wave on one band i feel sure that you can get the schematic from their web site
Trev

Ed_Dinning · 18th Dec 2017, 9:55 pm

Hi Gents, I seem to remember there was a PW Ascot? again 70's I think and it used a beam switching tube (as a synchronous detector?)

Ed

Philips210 · 18th Dec 2017, 10:28 pm

Hi.

There was a single span 3-valve selective receiver in the December 1955 issue of Practical Wireless. This can be found on the American Radio History website: http://www.americanradiohistory.com/...PW-1955-12.pdf

The first page with circuit diagram is attached below.

Regards
Symon.

dave walsh · 19th Dec 2017, 1:03 am

I think it might have been me that recalled a set with an extraordinarily wide range in one band

but I haven't found it yet either, although my mags are now [more or less] in one place. It wouldn't have been as far back as 1955 though Symon

. My guess is somewhere in the seventies? I might even have thought it was some kind of "spoof" article at the time. The "low" end might have been 2k metres-that seems to ring a bell. I will look again asap Stef.

Dave W

saddlestone-man · 19th Dec 2017, 4:49 pm

Thanks for all the help so far.

I just found this article by FG Rayer in the Jan 1958 issue of PW. FGR intends it to be a simple beginner's superhet, and for the sake of simplicity he omits the aerial tuning circuit and the local oscillator padder, and he gets a tuning range of 1600m to 200m, ie it's a LW/MW single-span.

He uses the standard IF of about 465kHz and so there are images being received which the WW single-span IF of 1.6MHz avoids.

best regards ... Stef

Philips210 · 19th Dec 2017, 5:22 pm

Hi.

I also recall a single span receiver from Radio Constructor around 1964. It was by Sir Douglas Hall and was thus not a superhet design.

Regards
Symon.

stuarth · 19th Dec 2017, 5:35 pm

Didn't Ambit sell a kit for a single span receiver? I think it used a ferrite rod aerial and varicap tuning.

Stuart

G6Tanuki · 20th Dec 2017, 3:59 pm

Looking at the designs posted - surely with an untuned antenna fed directly into the mixer without any signal-frequency selectivity there will be both horrendous crossmodulation between pretty much everything the antenna picks up, *and* the image-rejection will be zero!

20th Dec 2017, 4:33 pm

A low pass filter is used to stop the image getting through and a high level mixer minimises intermodulation. The ultimate example is the new SDRs, a low pass filter and an ADC, which could be considered as a mixer. It mixes the signal with the sample rate.

ms660 · 20th Dec 2017, 4:58 pm

The 1958 design is fitted with an all pass RF filter....Luv the direct drive 6V6...

Mag filler.

Lawrence.

G6Tanuki · 20th Dec 2017, 5:47 pm

Quote:

Originally Posted by ms660

The 1958 design is fitted with an all pass RF filter....Luv the direct drive 6V6...

It does look quite crazy to me: the 6V6 grid is being fed direct at IF - presumably as some sort of ghastly "power anode-bend detector/output-stage"? Designed by Dr. Frankenstein, or copied from a Jekyll-Hyde patent?

And I just hope that with the untuned front-end [remember that the 'mixer' will have significant gain at the IF] there weren't any navigation-beacons in the 400-500KHz range within earshot.

Part of me thinks this particular 'receiver' was published as a joke.

ms660 · 20th Dec 2017, 6:41 pm

I was also meaning the direct drive from the 6V6 to the loudspeaker, I like the "worth while" approach to the avoidance of a live chassis.

Lawrence.

18th Dec 2017, 7:38 pm	#1
saddlestone-man Hexode Join Date: Mar 2009 Location: Cirencester, Gloucestershire, UK. Posts: 391	Single span receiver article in Practical Wireless Hello all. A few months ago I started a thread about the single span superhet concept, whereby the long and medium wave bands are tuned as a single band. This was described in various 1934 issues of Wireless World. A contributor suggested that a modern version was described in (maybe) a 1960s or 1970s issue of Practical Wireless. I wonder if anyone has a good collection of PW over these years might recall this article and let me know. Thanks in advance for any help you can give me. Best rgds. Stef.

18th Dec 2017, 7:57 pm	#2
Dave Moll Dekatron Join Date: Feb 2005 Location: West Cumbria (CA13), UK Posts: 6,127	Re: Single span receiver article in Practical Wireless If anyone can narrow it down somewhat, I certainly have all the issues over that period. Unfortunately, I don't have the time to search through the 240 issues covering the two decades. __________________ Mending is better than Ending (cf Brave New World by Aldous Huxley)

18th Dec 2017, 8:27 pm	#3
Trevor Octode Join Date: Aug 2006 Location: Stoke-on-Trent, Staffordshire, UK. Posts: 1,082	Re: Single span receiver article in Practical Wireless Armstrong with their 626 receiver was a single span unit i.e. mw and long wave on one band i feel sure that you can get the schematic from their web site Trev

18th Dec 2017, 9:55 pm	#4
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Single span receiver article in Practical Wireless Hi Gents, I seem to remember there was a PW Ascot? again 70's I think and it used a beam switching tube (as a synchronous detector?) Ed

19th Dec 2017, 1:03 am	#6
dave walsh Dekatron Join Date: Jan 2006 Location: Ramsbottom (Nr Bury) Lancs or Bexhill (Nr Hastings) Sussex. Posts: 5,817	Re: Single span receiver article in Practical Wireless I think it might have been me that recalled a set with an extraordinarily wide range in one band but I haven't found it yet either, although my mags are now [more or less] in one place. It wouldn't have been as far back as 1955 though Symon. My guess is somewhere in the seventies? I might even have thought it was some kind of "spoof" article at the time. The "low" end might have been 2k metres-that seems to ring a bell. I will look again asap Stef. Dave W

19th Dec 2017, 4:49 pm	#7
saddlestone-man Hexode Join Date: Mar 2009 Location: Cirencester, Gloucestershire, UK. Posts: 391	Re: Single span receiver article in Practical Wireless Thanks for all the help so far. I just found this article by FG Rayer in the Jan 1958 issue of PW. FGR intends it to be a simple beginner's superhet, and for the sake of simplicity he omits the aerial tuning circuit and the local oscillator padder, and he gets a tuning range of 1600m to 200m, ie it's a LW/MW single-span. He uses the standard IF of about 465kHz and so there are images being received which the WW single-span IF of 1.6MHz avoids. best regards ... Stef Attached Thumbnails

19th Dec 2017, 5:22 pm	#8
Philips210 Nonode Join Date: May 2007 Location: Redruth, Cornwall, UK. Posts: 2,573	Re: Single span receiver article in Practical Wireless Hi. I also recall a single span receiver from Radio Constructor around 1964. It was by Sir Douglas Hall and was thus not a superhet design. Regards Symon.

19th Dec 2017, 5:35 pm	#9
stuarth Heptode Join Date: Feb 2010 Location: Heysham, Lancashire, UK. Posts: 669	Re: Single span receiver article in Practical Wireless Didn't Ambit sell a kit for a single span receiver? I think it used a ferrite rod aerial and varicap tuning. Stuart

20th Dec 2017, 3:59 pm	#10
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: Single span receiver article in Practical Wireless Looking at the designs posted - surely with an untuned antenna fed directly into the mixer without any signal-frequency selectivity there will be both horrendous crossmodulation between pretty much everything the antenna picks up, and the image-rejection will be zero!

20th Dec 2017, 4:33 pm	#11
Guest Guest Posts: n/a	Re: Single span receiver article in Practical Wireless A low pass filter is used to stop the image getting through and a high level mixer minimises intermodulation. The ultimate example is the new SDRs, a low pass filter and an ADC, which could be considered as a mixer. It mixes the signal with the sample rate.

20th Dec 2017, 4:58 pm	#12
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Single span receiver article in Practical Wireless The 1958 design is fitted with an all pass RF filter....Luv the direct drive 6V6... Mag filler. Lawrence.

20th Dec 2017, 6:41 pm	#14
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Single span receiver article in Practical Wireless I was also meaning the direct drive from the 6V6 to the loudspeaker, I like the "worth while" approach to the avoidance of a live chassis. Lawrence.