[Milsurplus] Re: SCR-274-N Transmitter Dial Etc.

[Hue Miller]

----- Original Message ----- 
From: <WA5CAB at cs.com>

> Why not?
> 
> In a message dated 7/6/2008 4:06:50 PM Central Daylight Time, 
> kargo_cult at msn.com writes: 
> > And i have wondered how on flattops, the transmitters were set up before
> > a flight.  Let's say, a patrol plane going out. You cannot tune up the 
> > transmitter
> > below the flight deck.

Somewhere here i have instructions for tuning up a civilian HF aircraft
radio. The instructions direct not to tune up in hangar. I assume, don't
recall if the instructions specifically explained this, that capacity effect
of hangar to wire antenna threw off the antenna resonance, compared
to the open air situation.  If the antenna is naturally resonant, this effect
isn't so strong, but if you have an electrically short antenna resonated
with external inductance, i suppose so. Possibly this applies even more
so below on a service deck, besides the caution to not operate any 
transmitter that might cause sparking from the antenna HV. 
So - i wonder: on the flight deck before scout flight, you could tune up
the transmitter oscillator using the LM freq meter. You do not want to 
actually radiate from the aircraft's antenna because who knows how
far that might go. ( I am thinking i recall reading of Japanese aircraft
being heard on runway, preparing....don't know where i read of this
however....)  Also there's no way to tune up on deck, to simulate the
trail antenna, which i suppose would have been more likely to be used
on scout patrol missions, than the fore&aft wire. However, on the SBD,
the receiver certainly wasn't accurate enuff to use it to calibrate the
transmitter. Loading the transmitter might throw the transmitter VFO off
a few kHz. The ship would not transmit or respond in any case, under
strict radio silence. I am just wondering how the patrol plane would come
up on frequency, close enuff that the transmission would not be missed
by the ship station. I don't think every SBD or TBM carried the LM freq
meter, did they? Not shown in any photo i have seen. Also, if the 
carrier's fighters were still using only HF gear, such as RUGF, how did
they tune up before take off? I suppose "radio silence" would have to go
out the door. -Hue  K7HUE