[GreenKeys] Frederick Electronics Help

[YIR]

For the record,  I have a Model 1203 but haven't dug into it yet.  Sorry =
no manual.
Pat  K7YIR
  ----- Original Message -----=20
  From: Dave Emery=20
  To: Jack=20
  Cc: greenkeys@mailman.qth.net=20
  Sent: Saturday, May 01, 2004 1:22 PM
  Subject: Re: [GreenKeys] Frederick Electronics Help


  On Sat, May 01, 2004 at 03:50:18PM -0400, Jack wrote:
  > ZCZC
  >=20
  > Does anyone have any information on a Frederick Electronics
  > Model 1202A VF Terminal? It is a 1 3/4 inch rackmount
  > unit that appears to be a RTTY terminal, but it has a bank
  > of switch selectable crystals with two switches labeled
  > "0-1" and "0-9". Maybe it's an FDM modem? It has
  > an output terminal strip that looks like it would be a
  > keyer for an external HV loop.

  I have one or one quite similar to it somewhere in my deep
  frozen junque collection in the barn.

  They are 60 hz or 85 hz shift FSK-FDM frequency agile VFT
  decoders (I forget which the 1202A is - there were both kinds made).

  The digswitches select the specific tone in the tone pack.

  The ones I have have an early PLL synthesizer for the local
  oscillator used to tune the specific tone (the thing is a VLF superhet
  which upconverts the incoming audio to a narrow band filter at around =
10
  khz if I remember right).   The switches select the tone by channel
  number...

  They were early 70s vintage with TTL logic and analog ICs of
  that era.

  And of course it need not be noted that such VF channel tone
  packs of 16 or 24 channels were very common distribution mechanisms =
for
  low speed TTY circuits in that period - in fact virtually all  long
  distance TTY circuits were transmitted in that format up until
  statistical multiplexors over high speed modems became common in the
  late 70s and 80s.

  I believe there were versions with a loop keyer included and
  versions that output RS-232 levels.

  --=20
     Dave Emery N1PRE,  die@dieconsulting.com  DIE Consulting, Weston, =
Mass 02493

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