1. Things you need to know about the new ‘Conversations’ PM system:

    a) DO NOT REPLY TO THE NOTIFICATION EMAIL! I get them, not the intended recipient. I get a lot of them and I do not want them! It is just a notification, log into the site and reply from there.

    b) To delete old conversations use the ‘Leave conversation’ option. This is just delete by another name.
    Dismiss Notice

Armstrong 509 tuner

Discussion in 'classic' started by Jim Audiomisc, Jul 5, 2019.

  1. Jim Audiomisc

    Jim Audiomisc pfm Member

    The 509 is something of a mystery. Someone I know has one at present on offer in eBay and he contacted me to ask about it. He'll be sending me some photos as - so far - I only have one b&W one of the front.

    I'm starting this thread just in case anyone else here has seen one or knows anything about them. If so, info would be welcome.

    Once I have more photos I'll put them onto the UKHHSoc site.

    I *think* they were a mono-only version of the 500 range AM.FM tuner specifically aimed at being incorporated in 'PA' systems. But no-one who worked at Armstrong that I asked about them could remember anything even that they existed!

    FWIW The eBay page is at
  2. cctaylor

    cctaylor pfm Member

    Certainly looks like a piece of professional kit as Jim describes.
    kevinrt likes this.
  3. Jim Audiomisc

    Jim Audiomisc pfm Member

    I now have some photos of the item on eBay. They show a unit that - overall - is different to the one shown in the only previous photo I had. Both show a '509' which has been incorporated into what seems a general PA system. But they seem to have been assembled by different companies with differing 'add on' items, etc. The 509 does have two nominal audio output sockets, but I don't think it has a stereo decoder. Need to check this, though, with a more careful study and look at drawings, etc.
  4. Paul R

    Paul R pfm Member

    The internal photos show an edge connector mounted on top of the PSU 'frame'. So possibly where a stereo option could go in the original application. So I guess a 523 with some deletions. I don't see an easy to find internal photo of a 523, but that would make it clear.
  5. Jim Audiomisc

    Jim Audiomisc pfm Member

    This has made me realise that I've not put copies of some of the circuit diagrams or unit photos on the web. So I've added doing this to my 'to do list'! However the layout for the tuners can be seen from this snippet from the 400/500 range circuit diagrams.


    In effect it is a 'top plan view'. Alas the photos I got of the 509 don't give this view so I'm trying to make sense of them in this context.
  6. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    I have a 523 but that 509 is a new one on me... seems to have a monitor speaker with matching transformer but no amp...
  7. Jim Audiomisc

    Jim Audiomisc pfm Member

    For me, the clear sign is that the 509 lacks both the stereo indicator lamp and the 'mono' switch. I've put a pic of the front panel here which shows these are AWOL.


    Along with some photos, the seller sent me a couple of short videos. I'll see if I can get a decent 'into the top of the set layout' image from those. A confusing factor here is that the FM only and AM/FM tuners had *different* locations for the plug-in decoder. (And the circuit diagrams I referenced show using the old M4 decoder, which changed to the M8 later.)
  8. Jim Audiomisc

    Jim Audiomisc pfm Member

    I've taken a snap from the video


    This shows no edge connector socket for a decoder, but shows the socket* where the C22 power supply + AF output would go as being vacant. So I assume all the power and audio arrangements are in the parts of the system external to the '509'.

    * The unused black edge connector socket near the top of the photo here.

    The video also looks like the monitor speaker may be driven by the external circuits despite being adjacent to the 509.
  9. Paul R

    Paul R pfm Member

    I think the 509 chassis is mounted into a larger chassis front alongside the monitoring arrangement, which has '100v line' marked on the rear. Which would make sense as part of a 'custom' PA rig.

    Internal photos of a 523 and the previous AM/FM tuner might be interesting.
  10. Jim Audiomisc

    Jim Audiomisc pfm Member

    I can't find any decent photos as yet of the 523. But this scan from an early leaflet


    Shows a top view of the426 which had the same AM/FM tuner arrangement as the 500 series. (In effect the 500 range was restyled reissue of the 400 range. Although some items were changed later on - e.g. change from M4 to M8 decoder, and different power amp boards.)

    Yes, this 509 is mounted into a bigger units with an add-on beside it, and another entire unit under it. The image I've had for ages is mounted into a totally different PA arrangement with a valve power amp.
  11. davidsrsb

    davidsrsb pfm Member

    Amazing complexity compared with a quality late synthesized superhet design
  12. Jim Audiomisc

    Jim Audiomisc pfm Member

    The days when transistors were new and ICs weren't on the menu. When all the coils were wound and then tweaked by hand, then fixed with wax.

    TBH The circuit diagrams for the 500 range are an utter nightmare to read. Not only complex, but weirdly laid out - and with 'bin numbers' on the components *not* component values.

    As an offshoot of this: I tried another websearch for the 509. As usual got all kinds of mis-responses. But also found again some of the old *600* range references where people in the USA in particular enthused about the 600's FM tuner sounding wonderful.

    Alas, I'm still little wiser about the 509. I guess like the 'J tube' it will remain a mystery with all involved now long gone, or having no memory of it. :-/
  13. Paul R

    Paul R pfm Member

    Only on the outside...

    Can't we infer it is a 523 chassis modestly adapted to the type of installation you might find in a factory back in the day of 'music while you work'?
  14. davidsrsb

    davidsrsb pfm Member

    True, a premium Sony PLL superhet with switchable ceramic filters would be a complex beast implemented with the 80s Plessey RF ICs, let alone discrete transistors and coils. I was designing military communications receivers in the 80s and worked with some amazing multi board equipment in milled out of solid chassis.
  15. Jim Audiomisc

    Jim Audiomisc pfm Member

    Yes, it does seem to be a chassis modified for a specific type of 'site/industrial' use. However what I find odd is the nature of the modifications. The main one being to make up a different fascia to omit the mono/stereo switch and stereo indicator. That meant a differently cut fascia *simply* to omit stereo. Yet the standard tuner was mono *unless* you plugged in an M4 or M8 decoder board.

    The point here is that making a small run of 'special' mechanical fascia plates, etc, would have added cost, etc.

    Similarly the PSU and audio output buffers were on a plugin board, so could easily just have been omitted/replaced in a standard model. Hence unless mass making was on the cards it seems weird to make these mechanical 'special' changes.

    Talking to Mike Solomon he thinks he may have seen them in Hospital Radio stations. But can't be sure as they may have been 'normal' tuners.

    I've been wondering if the extra cost was offsettable due to a quirk of ye olde Purchase Tax. i.e. let them be classed as 'industrial' units, thus taxed at a lower rate than consumer goods. Hence getting a return for Armstrong to cover the added costs whilst still being able to sell at a lower price. IIRC there was a similar trick wrt Loudspeakers back in those days. But I'm guessing here as this remains a puzzle.
  16. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Any number of possible uses in industrial and educational applications... background radio in factories, hotels, pubs, schools radio (many schools had a radio with 100V/Line and speakers in various rooms which could be selected as required.... ah the horrors of "country dancing"! Clarke and Smith was the main supplier though)
  17. Paul R

    Paul R pfm Member

    It's hard to tell for sure but it looks to me like the 509 metal work is cut for a pilot light and mono/stereo push button. So the difference is in the front panel and assembly wiring. Almost worth £32 for a closer look....
  18. Paul R

    Paul R pfm Member

    One hopes it is mostly done with software magic now...
  19. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    I would hope not! But it will be of course:)
    "Progress" is very much a double edged sword and I confess to being a Luddite! Much modern tech makes "consumers" "end users" out of all of us, no matter how much knowledge and experience in electronics one has amassed. I demand from test gear etc that it be repairable by myself, not only repairable but modifiable, able to be re-purposed if required. Often the only progress is in small size, light weight and relative cheapness but the actual performance of older gear is very good and as a bonus it can be kept running properly almost indefinitely.
  20. davidsrsb

    davidsrsb pfm Member

    My last two car head units have been SDR based and the weak signal performance when there is a strong signal around is pathetic compared with a decent superhet

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice