Yes, I have repaired a few of these, in my time as a Tech with Marconi Marine, and S.A.I.T. Marine. Sait called it an ER4250, but it's the same set. Main fault used to be the rectifier diodes for the P.A. valves/tubes heaters, they were directly heated types, hence the requirement for a d.c. supply. Sympton would be fuse blowing. There are two versions of this set, a channelized one for skipper-operated ships (usually under 1600 grt) and a direct frequency entry version for ships with a qualified Radio Officer. Made by Skanti of Denmark, unit runs of 115 or 220vac, (change links on main transformer), or 110 or 220VDC with a suitable motor alternator. The direct frequency versions were often fitted as a cheap update to an older pre-1970 dsb-cw/mcw station, giving 400 watts of ssb radiotelephony, without needing to replace the ship's main transmitter.