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Old 5th Sep 2022, 6:16 pm   #1
amandamalc
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Default Jason AM/ FM Tuner details

Hi all. I'm a new member and felt it was about time to join. As I can't seem to enter details in the 'about me' box, here's a quickie.

I've come into electronics late in life, in the footsteps of my 'techy' sister (sadly no longer with us).

I started finding a real interest in electronic things when my p/t employers started up the 'Radar Room: ( www.radar-room.co.uk ) BTW my sister's old site is still kept up and running by a Dutch friend of hers: ( https://www.izabella.tk/ ) I understand that some of her programming was very advanced ( hand machine-coding an MC68000 16 bit micro...? )

My question is thus. I recently took a fancy to an old Jason AM/FM tuner on the big auction site and won. Sadly we haven't managed to find out anything about it, not even the valve lineup as two are missing! We think that one is the EZ80, but what the other is is a mystery without the schematic. Can anyone help please? (I believe this is the earlier AM/FM model with the larger gold coloured front panel.) Any help with this would be greatly appreciated!
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Old 5th Sep 2022, 6:34 pm   #2
Sideband
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Default Re: Jason AM/ FM Tuner details

Hello and welcome. I'm sure there are threads about these tuners already. They used fairly generic valves. Possibly EZ80 (rectifier) and the other missing one could be EF89 (possibly there are two of those) if it's in the IF stage . In the tuner section it could be an ECF80 (or possibly ECF82) and an ECC81. Maybe if you can post a couple of pictures, that will also help to identify it, what valves it uses and what is missing.

What valves are currently present?
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Old 5th Sep 2022, 6:45 pm   #3
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Default Re: Jason AM/ FM Tuner details

Perhaps do a search on "Jasonkit" - I remember they did a lot of kit stuff in the late-50s through to the early-70s and you may find that there are specifications, circuit/schematic diagrams and kit-assembly instructions out there.

Example: https://www.radiomuseum.org/r/jasonk...uner_fmt3.html
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Old 5th Sep 2022, 6:57 pm   #4
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Default Re: Jason AM/ FM Tuner details

I must say this isn't the easiest project for a beginner to take on. You've come to the right place by joining this forum, but you may have a steep learning curve to confront.
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Old 5th Sep 2022, 7:05 pm   #5
Cruisin Marine
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Default Re: Jason AM/ FM Tuner details

Hi Amandamalc, welcome, and thank you for the radar room link, already I have learnt things of which I had not heard of before like the APS13 P51 tail radar, fascinating stuff- I shall look further, and ty again.

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Old 6th Sep 2022, 1:01 am   #6
Synchrodyne
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Default Re: Jason AM/ FM Tuner details

As far as I know, there were four Jason/Jasonkit tuners that fell into the AM/FM class, in all cases with AM coverage being MW only.

They were:

Jason AM/FM:

I have an outline description of the circuitry (not a schematic), with an estimated valve line-up. If this is the unit you have, please PM me for a copy.

This was very unusual in British practice in having a cascode RF amplifier, and unusually for such, an aperiodic input.

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Jasonkit Argonaut:

This used the same faceplate and basic chassis structure as the Jason AM/FM, but with quite different circuitry (e.g. no cascode). It was configurable as a tuner or a receiver.

The full constructional manual, including schematic, is available here: http://ukhhsoc.torrens.org/makers/Jason/index.html.

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Jason AM/FM2:

This replaced the AM/FM. It combined unusually elaborate FM circuitry with a decent AM side as well. Like the AM/FM, it had a cascode RF amplifier, this time with a tuned input.

I have the four-page brochure, which provides an overall description with the valve line-up. Again, please PM me for a copy if this is your unit.

The Beam Echo Avantic 612 appears to have been a clone of the Jason AM/FM2; the brochure is available at: http://ukhhsoc.torrens.org/makers/BeamEcho/index.html.

I have not found more detailed information on either of these. Notwithstanding that in circuitry terms the AM/FM2 was well above the general run of British tuners of the time, it seems to have escaped notice or detailed commentary.

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Jason AM/FMS2

This was simpler than the AM/FM2, with preset tuning on FM.

The brochure, including valve line-up, is available here, although labelled as “AM/FM2” rather than “AM/FMS2”: http://ukhhsoc.torrens.org/makers/Jason/index.html.

I have not seen more detailed information on this other than a Gramophone magazine 1958 May test report.

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Sometimes, “AM/FM” is conflated with the Jason/Jasonkit FM/TV Sound Tuners, insofar as they were intended for use with the AM TV sound of the time. In that case the six models at interest are: Jason JTV, Jasonkit JTV, Jason JTV2, Jasonkit JTV2, Jason Monitor and Jasonkit Mercury 2.

The Jason/Jasonkit tuner range is a little complex to unravel, and is perhaps best approached by treating the Jason and Jasonkit ranges as being separate but with some overlaps. Sharing the same model designation did not always mean that the Jason and Jasonkit versions were the same. E.g. the Jason FMT3 and Jasonkit FMT3 had different circuitry. On the other hand, the Jason Monitor and Jasonkit Mercury 2 shared the same circuitry. Not all Jason model had a Jasonkit counterpart and vice versa. And after the Argonaut, I think that the Jasonkit models had different cases even where they were otherwise the same as the corresponding Jason models.


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Old 15th Nov 2022, 3:37 pm   #7
amandamalc
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Default Re: Jason AM/ FM Tuner details

Thanks for the help. Please find (hopefully) the two images of the tuner I have this end.

It looks as if it is the first AM/FM one they made, as it is definitely not the later 'Argonaught' one as I have the manual for that.

Valve lineup anti-clockwise is Z719, Z719, X79, W727, ? , Z719, ? (the last of which is we believe an EZ80 rectifier). Any ideas please? As the wiring underneath seems intact, it would be nice to have this working again. There just doesn't seem to be any point in starting replacing caps etc. until we've sorted out the missing valve..
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Old 17th Nov 2022, 12:20 am   #8
Synchrodyne
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Default Re: Jason AM/ FM Tuner details

That looks like the Jasonkit Argonaut, built as a tuner rather than as a complete receiver. Both versions were envisaged in the original design. The tuner did not require the volume and tone controls, hence the blanks over the holes for same, nor the output valve and output transformer, hence the unused valve hole at the back corner. Also, in the tuner, the triode portion of the DH719/EABC80 (the missing valve in this case) was not used.

From the front, the Jasonkit Argonaut built as a tuner and the Jason AM/FM would look very similar, but the chassis layouts and valve lines up were noticeably different.



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Old 19th Nov 2022, 12:44 am   #9
Synchrodyne
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Default Re: Jason AM/ FM Tuner details

From the related thread in the “Radio” section, https://www.vintage-radio.net/forum/....php?t=195763:

Quote:
Originally Posted by Synchrodyne View Post

In general, the Jason/Jasonkit tuner range was quite complex. Jason and Jasonkit products with the same designation did not necessarily have the same circuits – although sometimes they did - and often they had different cases. And sometimes when the circuitry was the same, the Jason and Jasonkit versions had different names. For example, the similarly named Jason FMT3 and Jasonkit FMT3 had different valve lines up, but the differently named Jason Monitor and the Jasonkit Mercury II (as distinct from the original Mercury) shared the same circuit.
The attached is the outcome of a quick effort to map out on a spreadsheet the chronology of the Jason/Jasonkit tuner range from start to finish. It should be viewed as being approximate and probably incomplete at best.

Jason Tuner Chronology.pdf

Jason also had a French branch, the inception of which was noted in WW 1958 August, p.368. It might have lasted longer. Its FM tuner range included an FMT7 model, whereas Jason UK did not go past the FMT4 designation.


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Old 23rd Nov 2022, 3:24 pm   #10
amandamalc
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Default Re: Jason AM/ FM Tuner details

Thanks all who helped me out with this. STEVE has been amazing and sent loads of information to help identify the thing. It is indeed an Argonaught that has been made up as a tuner, rather than as a radio. All working now on both bands and performance is way, way, better than I thought it would be. Chris at the Radar Room aligned it for me once it was working, which made a huge improvement to the performance after first switch on. I think someone had been meddling in the past...! (Valve in wrong holder for starters?)
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Old 23rd Nov 2022, 7:25 pm   #11
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Default Re: Jason AM/ FM Tuner details

Most of the Jason kits worked remarkably well. I have the simpler FM tuner that I felt sorry for when I saw it on eBay. It is identical to one I had in the late 60's that got lost in a house move (mine has four EF91's). It does work very well and also responded well to a realignment.
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