Actually, both AN-74* and AN-104-* antennas were used by both Services - just at different times.  The AN-74 came first and was more expensive to make because it was a wrap around design with a crimp along the length of the copper radiating surface.  It also had problems with moisture getting under the metal and corroding the crimp.  The AN-104 used a plated drawn steel radiating surface that was pressed on over the wooden shaft.  Somewhere around here is a note to continue using the AN-74 until supplies are exhausted.

The Navy Airborne Radio Maintenance Notes (ARMN) dated November 1945 distinguishes between the two simply by calling the AN-74 the "old" VHF antenna, as contrasted with the "latest" AN-104-A (and eventually the -B series).  Turns out the AN-104 went through some growing pains with corrosion as well, finally getting some relief with the -B model that was plated with copper rather than iron.  (Or so said the ARMN).

- Mike  KC4TOS

AN-74:


AN-104-A (NASM photo):


On 11/11/2021 10:54 AM, MARK DORNEY via ARC5 wrote:
AN-74 was the USAAF version. AN-104 was the USN version

Mark D. 
WW2RDO

Begin forwarded message:

From: MARK DORNEY via ARC5 <[email protected]>
Date: November 11, 2021 at 10:38:39 AM EST
To: Robert Downs <[email protected]>
Cc: [email protected]
Subject: Re: [ARC5] T-23/ARC-5 antenna relay


Thanks everybody.  I was able to sort out the antenna configuration with the information you provided. The antenna is an AN-74. 

73
Mark D. 
WW2RDO


“In matters of style, float with the current. In matters of Principle, stand like a rock. “.   -   Thomas Jefferson 

Sent from my iPhone

On Nov 11, 2021, at 9:10 AM, Michael Hanz <[email protected]> wrote:

 The same relay was also used in the ARC VHF prototype set - (RE-16/ARC-5 antenna relay, T-89/ARC-5, and T-90/ARC-5 transmitters) and in the T-27/ARC-3.  So it got around...
- Mike  KC4TOS



On 11/11/2021 4:04 AM, Robert Downs via ARC5 wrote:
Yes.  The antenna relay for the T-23 and R-28 (and their SCR-274-N predecessors) was always mounted behind the top of the transmitter front panel.  There was never any separate VHF antenna relay unit as there was with all transmitter equipped versions of the MF/HF sets.  In both versions of the VHF sets, a short coaxial cable ran from the transmitter to the receiver.  And the VHF antenna was connected directly to the transmitter by a second coaxial cable.

Robert Downs


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of MARK DORNEY via ARC5
Sent: Wednesday, November 10, 2021 22:14
To: [email protected]
Subject: [ARC5] T-23/ARC-5 antenna relay

Anybody have any idea what the T-23/ARC-5 and R-28 used for an antenna relay?  Antenna feed from the T-23 was coax, and the RE-2/ARC-5 antenna relay didn’t have a post to connect coaxial cable. If an adapter was used, any help identifying the adapter would be appreciated   

Mark D. 
WW2RDO


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