[ARC5] AN/ARR-69 inquiry

[scottjohnson1 at cox.net]

Most all of the USAF larger aircraft carried UHF/DF.  And yes, as Francesco said, the four count gives enough time for the RMI to swing to the bearing.  It will hold that position, barring any-on channel interference.

The KC-97/KC-135 all carried the APN 69 rendezvous beacon, which transmitted at 9310 MHz  the worked with and radar that had a beacon mode (i.e., the receiver was tuned to 9310 MHz)  So the  beacon would receive an interrogation on 9375 MHz from the receiver aircraft (receive as in wanting to receive fuel) and would reply with a string of pulses, selected from the beacon control box.  (these were pre-briefed) the bomber would see a train of pulses at he azimuth of the tanker, starting at the range and radiating outward on the PPI.   The beacon in the KC-135 was in the base of the vertical stabilizer, right behind the elevator trim jackscrew.  Changing a beacon R/T was referred to as "having sex with the jackscrew"  The APN-69 was a sixty pound pressurized trashcan, but was quite reliable. Some aircraft later received the Motorola SST-181 Beacon, which fits in the palm of your hand.  I think. the APN-69 was deactivated and finally removed with the Pacer CRAG upgrades in the nineties.

Scott W7SVJ

-----Original Message-----
From: arc5-bounces at mailman.qth.net <arc5-bounces at mailman.qth.net> On Behalf Of zakariya.abu at yandex.com
Sent: Sunday, March 24, 2024 15:01
To: Francesco Ledda <frledda at att.net>; arc5 at mailman.qth.net
Subject: Re: [ARC5] AN/ARR-69 inquiry

Francesco,

Thank you for the reply and the interesting information.

Did the AN/ARA-25 hold the bearing "fix" with the RMI's arrow after each reception of transmission on UHF?

As I wrote before re. the KC-97, it used radar beacons for rendezvous.

I've just checked in a KC-135A manual from 1966 (rev. 1975), and it also mentioned such beacons: the AN/APN-69 and AN/APN-134. They operated at ca. 10 GHz. The KC-135A also the AN/ARA-25, as well.

73

Jan SP5XZG


W dniu 24.03.2024 o 22:11, Francesco Ledda pisze:
> There is no need for a continuous transmission for the UHF DF to lock.  Few seconds of TX are enough to get the bearing to the station.  That is that is needed!
> 
> Tankers also had dedicated beacons and later complementary TACANs.
> 
> Scott J. knows about this better than anybody else!
> 
> Best, Francesco K5URG
> 
> 
> 
> 
> Sent from my iPhone
> 
>> On Mar 24, 2024, at 14:32, zakariya.abu at yandex.com wrote:
>>
>> Jack,
>>
>> I think that TACAN has a dedicated A-to-A mode for finding air tankers. It was implemented starting from the AN/ARN-52 in ca. 1963.
>>
>> Methinks that homing on a tanker using eg. an ARA-25 UHF DF would require constant transmission from the tanker to facilitate finding it. What kind of transmitter other than UHF COM radio would be used then unless there was an extra system using CW or MCW for identification? Maybe our experts and practitioners could share how this was done in the 1960s and 1970s?
>>
>> 73,
>>
>> Jan
>>
>> W dniu 24.03.2024 o 20:12, Jack Antonio pisze:
>>> Maybe also used to home in on a tanker?
>>> Jack Antonio
>>> WA7DIA
>>>> On 3/24/2024 1:55 PM, scottjohnson1 at cox.net wrote:
>>>> Since Francesco is busy yacking to me on the phone, I will answer.  The ARA-25/50 are very effective, and are typically used LOS, and in the 225-400 MHz they are quite accurate.
>>>> Many downed pilots and aircraft (as well as ELTs going off on the ramp) have bee located with these adapters.
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