[ARC5] ARC-5/SCR-274 Navagation Receivers?

[Mike Morrow]

>But the Navy scouts and scout bombers did have RDF. The loop was directly in 
>front of the radio operator. I suspect it was manually operated by the radio 
>operator.

That's the DU-* loop, and it was manual in every way!  It fed into a RU-*
receiver that was paired with the GP-* transmitter.

But after the ZB-* homing adapter became available in 1940, photos of
all such aircraft that I have seen have the ZB-* homing adapter where the
DU-* loop was on earlier aircraft, on the top surface forward the radio
operator/gunner.

> In the Pacific the fighters (F4F, F6F) were used for CAP and as
> escorts for the bombers. When used for CAP they were never out
> of sight of the carriers.  When flying escort for the bombers
> they just followed!

Even a single-seat fighter aircraft using the RU-*/GF-* command set could
easily use the ZB-* with the RU.  Dual-band coil sets for the RU were made
that had one band for the frequency of the GF transmitter, and the other
band for a portion of the broadcast band selected specifically for what
the ZB homing adapter puts out.  The bands could be swapped remotely
using a spline.  The output of the ZB was connected to the RU at the RU
LOOP terminals, so the input to the RU could be swapped from antenna 
to ZB using a spline to the RU's ANT/LOOP switch and selecting LOOP. 
The mounting fasteners for the ZB match the RU receiver tube cover,
which could be removed and the ZB mounted in its place.  Thus, the RU
did not need to be accessible to the pilot to go from HF communications
to VHF homing function and back.  Just flip two selector switches and
retune the RU.

The old DU-* manual loop would never have been usable in such fighters,
but the ZB worked fine.  With the ZB, a fighter did not need to worry
about getting out of sight of his carrier.

Mike / KK5F