[MRCA] ZB-2 control box and Antenna control box questions

Mon Feb 14 12:16:26 EST 2022

First of all, in the context of the ZB, RU and ARB, forget the DU. It 
was not used in connection

with the ZB system.

.Secondly, although I have put together a ZB and ARB system, it was not 
done with any official

wiring diagram, just the fact that somewhere on one of these lists, I 
saw a post that said the

ARB and ZB combo could be used without the control and relay boxes.  So 
I hooked mine up

with that in mind. Maybe it is not accurate and needs the control box. 
So I am looking for

any official document (probably aircraft wiring diagram) showing the ARB 
and ZB interconnection.

The signal transmitted by the YE is an approximate 246 MHz carrier 
modulated with a

subcarrier between 530 and 850 kHz. From now on I'm just taking the 
approximate center

and say 700kHz. The 700 kHz signal is either keyed CW or MCW with the 
morse letter indicating

direction, and every few complete revolutions, a revolution consisting 
of just an ID. There is

one set of letters for the course information, and different set used 
for ID purposes.

The ZB receiver input is a dedicated antenna, a 1/4 wave spike. The ZB 
receiver is a TRF that

recovers only the 700 kHz signal. This is fed from the ZB receiver to 
the external receiver, what ever it

happens to be.  This external receiver is tuned to the proper frequency 
and its audio output contains

the information for the pilot.

Now whether or not the ZB antenna relay and pilots control box are 
necessary, depends on

which receiver (RU or ARB or whatever).  The ARB can select its two 
inputs by means of the

ARB pilots control box. So that would eliminate the need for the ZB 
antenna relay.

Hope all this helps. Again, I was under the impression that in the case 
of the ARB, the

ZB control box and relay box were unnecessary,  Maybe I'm wrong?

Jack Antonio

WA7DIA

On 2/13/2022 2:36 PM, MARK DORNEY wrote:
> How does the ZB get connected to the aircraft antenna? For either an RU or ARB Operator to be able to hear the transmission from the YE transmitter, the ZB adapter has to demodulate the signal. Does the ARB pick up the carrier wave that contains the signal from the YE transmitter, then sends it to be demodulated is the ZB Adapter, then is sent back to the ARB  for the operator to hear?  Or does the ZB process the signal in independently from the ARB?  And why would there even be a ZB Pilots control box if it were not necessary?  And why a DU-1 Antenna when a non- directional type antenna is what is called for ( remember, the YE transmitter is transmitting CW signals out on a directional antenna that transmits a different letter every 30 degrees of rotation of the YE antenna. A DF antenna is not needed to know what direction the carrier is in: all the pilot/ navigator would have to do is figure out a back azimuth from the coded signal sent by the YE transmitter that he is receiving and get the aircraft pointed in that direction ).   A loop antenna, even in a teardrop cover effects the aerodynamics of aircraft, and especially for fighter aircraft, were not practical.
>
> Mark D.
>
>
> “In matters of style, float with the current. In matters of Principle, stand like a rock. “.   -   Thomas Jefferson
>
> Sent from my iPhone
>
>> On Feb 13, 2022, at 2:01 PM, Jack Antonio <scr287 at att.net> wrote:
>>
>> First of all. Mike Hanz's website has excerpts from the ZB-3 and AN/ARR-1 manual, which describes the
>>
>> differences between the ZB-1,-2, -3 and AN/ARR-1.  This should answer your questions as to the control box
>>
>> and relay box. Robert downs also has a reprint of the ZB-2 manual.The primary purpose of the relay box
>>
>> is to switch the input of the LF/MF receiver between the antenna and the output of the homing adapter.
>>
>> It was always my understanding that the ARB was designed to support the homing function, making
>>
>> the control box and relay box unneccesary for the ARB.  But, that leaves out the LOCAL/DISTANCE function
>>
>> as well as basic ON/OFF of the adapter.  The ARB has an internal relay to select beween the homing
>>
>> (L1 and L2) and communication (AT and AF) selected by the bandswitch on the control box.
>>
>> I set up and displayed an ARB/ATB/ZB setup at Gilbert back in 2013, using the proper test box as a
>>
>> signal source(with the output padded down to leakage levels as it was still on about 246 Mc). I did
>>
>> not include either the control box or relay box thinking they were unnecessary. And everything worked.
>>
>> I have never seen an official document showing the interconnect diagram of the ARB and ZB, and if
>>
>> there is one, I'd really like to have a copy.
>>
>> Hope this helps.
>>
>> Jack Antonio
>>
>> WA7DIA
>>
>>> On 2/13/2022 11:32 AM, MARK DORNEY via MRCA wrote:
>>>   I’m not sure what a ZB Antenna control box and a ZB Control Box are. I think the ZB Control box is a Pilot’s Control Box CZR-23214. I have no idea what a ZB Antenna control box is. All help is appreciated.
>>>
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