Marconi Marine Pantenna III
 

Hi all,

I have just picked up this Marconi Marine Pantenna III from a local charity shop and I have no idea what it is (preamp?). I can't find much information or pictures anywhere on the inter-web. Any information would be very appreciated.

Re: Marconi Marine Pantenna III
 

Just opened it up. It's a Pantenna AM/FM Amplifier. Serial No. 1140.

Re: Marconi Marine Pantenna III
 

There's a reference here: https://www.vintage-radio.net/forum/...4&postcount=50

Re: Marconi Marine Pantenna III
 

Harry, A 75 ohm coax would go from cabin to cabin, each cabin having an output box that had something simple like a 1K resistor and a .1 uF cap to feed a radio. The very far end of the coax was terminated with a 75 ohm resistor.

It would be most useful for all of us who have numerous receivers. You might site it and its aerial far from the house to minimise local qrm.

I was most familiar with the Redifon valved version. Crew members would try and get better signals by opening up the box and tapping in. It was usually a devil of a job to find multiple faults and breaks in the line.

Sometime the r/o would feed in a sig gen at about 600 kHz, modulating the sig gen with an HF receiver tuned to the BBC world service.

73, Andrew

Re: Marconi Marine Pantenna III
 

Thanks for the photos of this unit - the manual has none. I got a manual recently, just to see some details. Further to what Synchrodyne said this comes in three versions to give additional Band II or Bands I+II distribution. The basic unit is specified for 100kHz -30MHz and includes filtering with sharp stopbands for the marine bands 370-550kHz and 1.6-4.0MHz. Four outputs are available to supply chains of up to 20 'outlets' in cabins, and slave amplifiuers were available to expand the capacity.

Further options were a high-impedance active antenna pre-amplifier and a modulator to provide a local feed of additional programme material as Andrew mentioned. DC and AC PSUs were offered.

Main devices were BFY90 with a dual-gate 40822 MOSFET for the pre-amplifier. The stopband filter is a passive 14-pole unit. I attach the main schematics.

Re: Marconi Marine Pantenna III
 

I've parts of this system, which I rescued when I removed it to free up space on a bulkhead on one of my vessels. I hoping to use them as the basis of a "pantry transmitter."
I thought I had also rescued the complete manual, but can only find the circuits for the bits that I've got.


Mike A

Re: Marconi Marine Pantenna III
 

Mike - The only other bit of my manual which could be of use to you is the AM/FM diplexer unit, let me know and I'll scan that.

Regarding pantry transmitters, I'm sure we'd all like a view inside the modulator, the two coils being the only parts not specified on the schematic.

Re: Marconi Marine Pantenna III
 

Hello Julian,
attached photos of the inside of the AM Modulator.
No Markings on the coils I'm afraid, however the circuit shows them both as "RP 208" Repanco? Denco? I assume they are off the shelf items. Marconi made coils would have had "WISxxxxx" or something similar written on the can.


Regards Mike A

Re: Marconi Marine Pantenna III
 

Thanks for that, Mike. Don't know why I never considered they would be in screening cans, but it should be easy to find a pair of suitable RF coils with matching taps or windings. A typical IFT with the fixed cap removed should give coverage of the lower half of MW, say 530-1,000kHz.