[Boatanchors] B-17 antenna connection

[Dave Marquart]

Thanks Mike and all!  I just knew someone on the site would have the
answer.   All the tuning on the 375, ANTENNA COUPLING, using BC221. Cold
and noise makes for a busy radio operator. And a gunner when the time came.

On Nov 27, 2016 6:45 AM, "Michael Hanz" <aaf-radio-1 at aafradio.org> wrote:

> Looks like the 34kB image didn't make it through, so here is the text:
>
> (e) _Antennae
>
> _            The Liaison set employs either of two antennae.  The trailing
> antenna is held on a reel, Type RL-42, mounted on the lower left sidewall
> at Station 6D.  It is operated by a 24 volt D.C. motor controlled by a Type
> BC-461 control box on the upper left sidewall at station 5F.  A counter on
> the box indicates the amount of wire extended, and a warning lamp lights
> when both the landing gear and antenna are extended.
>
>             The skin of the airplane serves as an antenna for the Liaison
> set with a lead-in connected to the left wing at the main tank gage cover
> and brought through an insulator in the upper left side of the fuselage
> just forward of Station 5O.  Both Liaison antennas are connected to the
> antenna changeover switch and through the switch either antenna may be
> connected to the set.  The antenna switch is on the upper left sidewall at
> Station 5G. _
> _
> end excerpt
>
> On 11/27/2016 8:28 AM, Michael Hanz wrote:
>
>> I dug around my documents and found this excerpt from the manual for the
>> B-17F concerning your question, shown below, Dave.  It was in effect a loop
>> antenna.  Used on the earlier B-17s for the Liaison antenna (paradoxically,
>> the command set was connected to a conventional top of the tail to radio
>> compartment antenna.)  The early B-29 also used the loop (for the command
>> set antenna,) with a short wire running between a lower feedthrough
>> insulator on the starboard side of the fuselage to a point on the rear of
>> the No. 3 engine nacelle, employing a portion of the skin of the wing and
>> fuselage back to the ground of the transmitter. At HF frequencies, the
>> aluminum skin between the nacelle and the ground connection point for the
>> transmitter has a measurable complex impedance (aluminum is more lossy than
>> copper in this regard), so there was apparently some radiation from the
>> skin at those frequencies.  It could probably be argued that the majority
>> of the loop radiation came from the wire between the wing and feedthrough
>> insulator, but I have not seen any discussion on that issue in the
>> literature.  Overall, the concept wasn't as efficient a radiator as a
>> conventional longer wire antenna, so was eventually abandoned in favor for
>> the more familiar tail top to fuselage configuration used in smaller
>> aircraft.  The B-29 command set eventually used anindependent horizontal
>> stabilizer to fuselage insulator long wire for the same purpose as the
>> liaison fixed wire.  See my writeup on that at
>> http://aafradio.org/NASM/RHAntennas.htm if interested.
>>
>>
>>
>>  73,
>> Mike  KC4TOS
>>
>> On 11/26/2016 9:58 PM, Dave Marquart wrote:
>>
>>> OFF topic..  After reading the B-17 manual on radio equipment - I saw the
>>> following..
>>> The liaison receiver on the radio operator’s table covers a frequency
>>> range
>>> from 1500-18,000 Kc. It uses the same antenna as the transmitter: the
>>> skin
>>> of the airplane. This is connected to a throw switch on the left side
>>> wall.
>>> This switch can change over to the trailing antenna (also on left side
>>> wall). The trailing antenna is operated from a control box to the right
>>> of
>>> the change-over switch.
>>> Can someone tell me how they used the Skin of the aircraft for an antenna
>>> when the negative side of the Battery, generators, equipment were all
>>> using
>>> the frame (skin) of the aircraft?  What am I missing?  Thanks..
>>>
>>>
>>> Dave Marquart
>>>
>>
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