Fw: [Premium-Rx] Eddystone EC-1837/1

[Michael O'Beirne]

----- Original Message -----
From: "Michael O'Beirne" <michaelob at tiscali.co.uk>
To: "Ahmet Gundes" <ahmet-m at usa.com>
Sent: Saturday, February 26, 2005 6:04 PM
Subject: Re: [Premium-Rx] Eddystone EC-1837/1


> Dear Ahmet,
>
> I know all about the 1837.  I have the manual for the very similar 1838,
but
> it's bulky and the circuit occupies 4 pages of A4.
>
> In essence it was originally designed as a maritime set.  The era is late
> 1970s - early 1980s.
>
> The size is 19 in wide x 5.25 H x 13D ie standard rack.
>
> Freq Coverage:  100kHz to 31MHz in 9 bands.
>
> IFs: (1) 1340 - 1350kHz nominal to provide fine tune facilities on ranges
5
> to 9 (ie above 1600kHz)
>        (2) 100kHz
> Selectivity: 8, 3, 2.4, 1.3 and 0.4kHz.  The 2.4kHz SSB filter is
> assymetrical to MPT 1201 and CEPT specs.
>
> Image rejection: 50 to 70dB from 500kHz to 30MHz.
> IF rejection: 60dB from 1.6 to 2.9MHz, and 85dB above 2.9MHz.
>
> Scale - digital to 100Hz.  Yellow LEDs. easy to read.
>
> Modes:  AM, CW, USB.  No LSB on the 1837/1, but there is LSB on the
1837/2.
> Selectivity with ceramic filters, though there may be a facility for
crystal
> filters for SSB (not sure).
>
> FSK with an optional module.  This is a relatively simple circuit, broadly
> similar to the ST5 design.
>
> It will work with the EP1061 panoramic display unit fed from the 100kHz IF
> output.
>
> It is basically a conventional double conversion circuit using an FET RF
amp
> and FET Mixer with three tuned circuits betwen aerial and mixer, (just
like
> a traditional AR88) but there is a frequency stabiliser on the two LOs.
[In
> the range 840 - 1600kHz it is single conversion only to 100kHz and there
is
> no frequency locking facility.]
>
> In essence the locking facility works as follows.  The difference in LO
> frequencies is stored and compared every second, and then an adjustment is
> made to the 2nd LO to restore the overall tuned frequency.  The problem is
> that if there is drift you are always a second behind, and the digital
> display is also a second behind.  At the worse it can sound like heavy
> breathing in and out if you see what I mean.  I tried one out and it drove
> me mad.
>
> Once locked, the drift is supposed to be not worse than 5Hz per day or 5Hz
> in any period of 15 mins for a 7C change, but on the one I tried it there
> was drift in between the 1 second locking points as described above.  May
> have been a fault, perhaps why it was for sale!!!
>
> The 1837/1B has a fine tune facility of +/-5kHz.
>
> The Marconi Pacific is the 1837/15.  The panel is grey with chrome handles
> whereas the Eddystone colours are a cream panel and square black handles
> angled slightly away from the panel.
>
> I would never class this receiver as a Premium Receiver.  My advice is to
> give it a miss unless you collect Eddystone receivers and it's not too
> expensive.  Nicely made inside though.  I hope this helps.
>
> 73s
> Michael
> G8MOB
>
>
>
> /
>