[Premium-Rx] Marconi H2550 HF Receiver

[Berndt Josef Wulf]

G'day,

I recently bought a Marconi H2550 HF receiver at a local auction. This
receiver covers 0.01-30MHz, supports USB, LSB, ISB, AM and CW, has 255
memory channels and scan mode and sports a large dot matrix VFD type
display. It employs a sigma-delta ADC in the IF. I believe it to be one
of the first receivers that used this technology. According to the
Jane's Book, production continued until 2010 and is still in service and
supported.

Operation is through menu screens that are arranged in a logical manner.
It takes a little time to get used to navigating through these menus.
The firmware loaded in this particular unit appears to be buggy, as it
requires selecting CW mode before it produces audio from its built-in
speaker that is hidden behind a plastic membrane, which reduces the
quality of the audio. Audio produced in the headphone set is good. The
sensitivity of the receiver is excellent and initial tests produced MDS
< -133dBm in CW mode.

I'm now looking for user's, operations and service manuals. Of
particular interest is any information on the installation showing the
pin-outs for the various connectors.

I'm also looking for any information on the Marconi H1542 exciter. I
believe to have found the line audio outputs but still have to find the
PTT/Key line. 

Any help is very much appreciated.

73, Berndt
VK5ABN