Following on from my dialogue with Gerry O'Hara where I mentioned the difference
in knob styles ( silver metal centre and skirt versus grey plastic) with regard
to year of manufacture I noted something interesting on Ebay yesterday.

A 940 on a 906 plinth had been listed with the serial number LT1245 indicating
that it was manufactured in December 1968. The set had what I had always
regarded as the earlier style knobs with grey plastic skirt.

Yet my 940 with a serial number advanced 9later) by around 120 or so and with
the later style metal skirted knobs and which I purchased new in November 1968
had the serial number prefix of DT indicating that it was manufactured in April
1968. How could this be?

My 830/7 also with the metal skirted knobs similarly has a serial number prefix
indicating manufacture in May 1968 which is in tune with the style and
manufacturing date of my 940.

Essentially I am no longer sure that the serial numbers and prefix means much at
all.

Mike




--- In eddystone_radio_users@..., "g8guh" <gerryohara@t...> wrote:
>
> Hi Gerry,
>
> This answers my questions. Reading through the various notes on the
> removal of filters prior to release I could not figure out what they
> were talking about because my 830 had the standard S3 micro switch
> which seemed to shunt the standard glass envelope crystal. So I know
> where I am now. Appreciate the help.
>
> -----Original Message-----
>
> Hello Mike,
>
> So you are moving on the 'Jewel in the Crown' of Eddystone valves
> sets. I had great fun sorting my 830/4 out and it is a great
> performer, even with the little 'niggly' remnant issues. I will try
> to answer your questions as best I can:
>
> - I understand that the 'Piccolo' system was some sort of coded
> signal used by the British diplomatic service in the 1960's that
> required a sharp cut-off filter in the receiver. The 830/8 model,
> developed for UK diplomatic service use, was fitted with these
> filters in lieu of the standard CW (100kHz) IF filter. This seems
> to have entailed some 'butchery' of the second IF circuitry that
> included removal of the microswitch (S3) that switched in the 100kHz
> filter. I gather that it was standard practice to remove
> the 'Piccolo' filter prior to releasing these sets onto the surplus
> market. I don't think that any of the 830/7 series included the
> Piccolo arrangement (though with Eddystone, who knows for sure!) -
> my 830/4 is based on the 830/2 circuitry that was outmoded (ie.
> replaced by the upgraded 830/7 circuitry) two years before my set
> was manufactured (December, 1968 - it is newer than yours!).
>
> - The crystal 'bank' you refer to that is present in your 830/7 is a
> standard fitment to all 830 series receivers. The (eight) crystals
> in the bank are switched into the 1st LO circuit on the 'A'
> through 'H' positions of the chrome lever-switch located behind the
> bandchange switch on the front panel. This sets the 1st LO onto the
> selected crystal frequency selected instead of being free running
> (position 'M' on the same switch). The manual describes how to
> select crystals for any received frequency you wish above 1.5MHz
> (below this the set is single conversion). I took a handful
> of 'junk' Style 'D' crystals from my junk box that were in the
> correct range and fitted them to see if it worked -it did! Attached
> is a little spreadsheet I started to develop to provide the crystal
> frequency v received frequency based on the instructions in the
> manual (I think it still has a bug or two in it - but if you want to
> experiment it may be a useful start). The spreadsheet gives the
> tunable range available (via the free running 2nd LO) for any
> particular crystal frequency (the ones in the table are my 'junk'
> crystals, which were all suspect 3rd harmonic ones (hence
> the 'suspect fundamental' calculation column). You enter your (3rd
> harmonic) crystal frequencies in the yellow cells. If you have
> fundamental crystals, enter the directly in the green cells to the
> right of the 'Fund' cells.
>
> - The 2nd LO can also be crystal controlled (see manual) but only
> one crystal can be fitted. This must have been available for very
> specialized single channel operation modes. I have not experimented
> with this, but instructions are given in the manual (downloadable
> from the EUG site).
>
> Not sure about the 'knobs' issue. I would suspect that there was
> not a 'hard' cut off date for change-over to the newer (silver-
> skirted) style - I gather folks at Eddystone were keen on using up
> surplus stock, even if this was discovered to be available after
> production runs had started with the newer stuff!
>
> Hope this helps clarify things - good luck!
>
> Gerry, G8GUH
>
> -----Original Message-----
>
> Hi Gerry,
>
> Since I have gotten the 770U working on all but the to Band 1
> (though it may need alignment eventually ) I have left that for the
> moment while I source a Band 1 coil and while the cabinet, intenal
> chassis side plates and replica speaker plinth are at the paint shop.
>
> So I have now had a look inside the 830/7 and re-read your article.
> I have also read the various notes from the Newsletters with regard
> to disabled or removed Picalo filter crystals but am not sure I
> follow the whole thing. On opening up my 830/7 the receiver looks
> vitually unused however the set of 8 crystals are not fitted. These
> seem to be selected/activated by switch 6b but are not listed in the
> parts list.
>
> The various articles on the Picalo filters seem to refer to a micro
> switch on the selectivity switch. This switch appears to exist on my
> receiver as
> S3 which shorts out or not XL1 in the selectivity circuit.
>
> Essentially I am not sure what the various articles are referring
> to. Are they referring to the plug in crystals A thru H (which are
> missing on my
> set) or XL1 which is in the selectivity circuit after the second
> mixer.
>
> And then whatever the case are the crystals for positions A thru H
> available?
>
> This receiver was manufactured in mid 1968 same time as my 940. On
> both receivers the small and on the 830 mid sized knobs are of the
> type withsilver metal skirts and silver centre discs whereas on both
> receivers the large knobs have the plastic grey centre and on the
> 940 grey plastic skirt.
>
> On a 830/7 sold a few months back on E-bay for £680 to a US buyer
> all knobs were of the silver metal variety and I took this to be a
> later than 68 set.
> However all of my other sets 1964, 65 and 66 (EA12) have the all
> plastic variety for all knobs and the RF/IF knobs on the EA12 are
> the same as your 830/4. On my 830/7 the RF/IF knobs match the others.
>
> I had always taken the knob style as a rough indicator of the year
> of manufacture but if your set was made in 68 Eddystone must have
> been running the two cosmetic styles at the same time.
>
> look forward to your input on the crystals.
> Best Mike,
>
> >-- Original Message --
>
> Sounds good Mike. The 'hands slapping' case removal technique was
> taught me by my girlfriend's dad back in the early 1970's (he
> obviously used it daily at his work at 'the Ministry' and had
> callouses at the contact points on his hands) - I watched in horror
> as he applied the technique to my beloved EC10 one day', fag in
> mouth and gobs of ash spraying everywhere. It usually works, though
> some sets need a bit of persuasion using a broad-blade screwdriver
> inserted between the case apertures and the chassis, using a couple
> of bits of plastic for protection. Perhaps the ash acts as a dry
> lubricant for future removal episodes - cannot test this theory as I
> have never smoked (except when testing AC/DC sets). I liked the
> toast story also in Bill Cooke's article. It reminded me of a few
> incidents in my radio/TV repair shop days... especially some of
> those involving 'Johnny-one-arm'.
>
> 73's
>
> Gerry
>