[Milsurplus] Re: 3 loop antennae on Mariner

[Jack Antonio]

Hue and the group,

> I recall reading about a Bendix DF receiver that did away with the 
> conventional BFO, it had an audio oscillator ( !!) keyed by the
> detected RF from the IF. 

In the BC-433, the "BFO" function was done by suppressor grid modulating
an IF amp with 400 cycle power supply voltage. This may have been in the later
units, I don't think it was in the earlier ones. 

> BTW, lemme ask this: with the DW loop, which is similar to the DU,
> except the DU was for  use inside glassed in cockpits, and on the
> DW, the long neck extended thru the plane's skin and the actual
> loop was outside, how in the wind slipstream did the operator
> turn the loop, and keep it in  position when seeking a null? The
> mechanics of the loop wouldn't seem to be up to this.

The only mention I can find in a quick look at my DW manual, only mentions
finding a location that is free of turbulence, and away from "other fuselage
structures". It does mention locking the loop into position with the locking bar.
Also the loop isn't really all that big, and what was the cruising speed of a PBY-
125 mph or so?  Also it looks like the DW loop assembly sits on a thrust
bearing, and there is a handwheel on the extension shaft.

> Also, i saw a photo of some kinda PBY where it looked like a DU
> control box was at the top of his big stack of radio equipment
> ( RU's and LM and such ). In the photo you could not see the loop,
> which of course wouldn't work inside the airframe anyway. So i'm
> wondering if somehow it was a model DU, with the loop outside
> the plane somehow? No, that does not make sense. I better look
> for that photo so i can  document that to you.

Comparing my DU with the pictures in the manual for the DW, I don't
think you could tell the difference. I need to piece together my
photocopied DU manual and do a side by comparison, but I think
the two units are pretty much identical.  

Anyone out there have an interconnect cable from the DU to the RU?

73

Jack Antonio WA7DIA
scr287@sbcglobal.net