[Milsurplus] Freq. Coverage of Navy Transmitters

[w8au at sssnet.com]

At 07:53 PM 11/1/04, howard holden wrote:
>The TBW is not, as far as I know, a shipboard transmitter, rather a beach
>unit. Remember, it comes in the watertight cases, and is designed to be set
>up as a free-standing field unit. The TCS, on the other hand is a shipboard
>unit.
>
>The puzzle to me is why did the TBW have the LF unit? Any antenna they could
>set up on the beach would be a pretty inefficient radiator in the LF range.
>The upper MF and HF would be far more useful and practical for shore-ship
>comms. Perhaps it was to be able to communicate with merchants involved in
>landings, who might have had only MF/LF rigs. That could explain the MCW
>capability on many Navy transmitters.

Howie:

If you have the TBW manual you see the antenna setup they used for LF and HF.
The end fed top wire against the low counterpoise wire, although small for 
the wavelength,
appears to be a good try for some sort of efficiency, at least enough to 
communicate
with merchant and transport ships.

>The other puzzle is why the Navy used suppressor-grid modulation instead of
>plate  mod on some transmitters? Typical power output with suppressor mod is
>about 1/4 of the CW output. Granted, the weight and space savings over plate
>mod on the TBW might mean something to the guys who had to muscle it ashore,
>but with a hulk like a TBL, at 700 lbs (not including the MG set), what
>would another 150 lbs mean, instead of the 75 lbs for the suppressor
>modulator.

The resort to efficiency modulator schemes seems to follow the size of the rig.
The TBK has a plate modulator (which changes the nomenclature to TBM) and
as the power and size drops (TDE, TBL, TBW, TCM, etc) you have grid modulation.

This pattern is not consistent, tho, (TCS) and we are left wishing we knew the
real reasons.   Maybe parts count, maintenance and weight were factors?

Perry   w8au