[ARC5] AN/ARC-5 R-23 Question

[Mike Morrow]

Mark, the audio signal that is fed to the R-23* adapter panel plug comes from the cathode of the 12A6.  That AF is filtered to pass low frequency AF (below 100 Hz) that the MX-19 ILS adapter sends to the AN/ARN-9 as localizer signals.

Much better 600 ohm AF comes from the secondary of the AF output transformer which is fed to rack audio bus A or B depending on the position of the audio bus selector switch for that receiver when it is in the rack.

Only R-23*, R-24/ARC-5, and R-148/ARC-5X put out a filtered AF signal from the 12A6 cathode circuit, but that AF is not designed or intended for normal receiver headset use.

Mike / KK5F 
-----Original Message-----
From: Mark K3MSB <mark.k3msb at gmail.com>
Sent: Dec 27, 2023 3:24 PM

Hi Mike 
 
Thank you for taking the time to post that!   Much appreciated.
 
You noted that the C-24/ARC-5 had no audio jack;  the audio jack in my HB version is connected to J1-4 for the instrument landing system.
 
73 Mark K3MSB

On Wed, Dec 27, 2023 at 7:37 AM Mike Morrow <kk5f at earthlink.net (mailto:kk5f at earthlink.net)> wrote:
The CW-4/ARC-5 and CW-5/ARC-5 are nothing more than black plastic screw-on covers for two different diameters of A.R.C. connectors found in the AN/ARC-5 system to cover unused connectors.  They are mentioned in several places in the LF/MF/HF AN/ARC-5 Maintenance Handbook.

THE ONLY ADAPTER PANEL THAT HAD A CONNECTOR WITH CW-4/ARC-5 COVER ON ITS FRONT IS THE MX-19/ARC-5 ILS Adapter...see below.

HOWEVER  the R-23* and R-24/ARC-5 came from factory with CW-4 on the spline connector for its LOOP selector switch.

There are four very different AN/ARC-5 receiver adapter panels: 

MX-19/ARC-5 Audio Adapter:  This adapter has ONLY ONE function to connect ONLY the R-23* or R-24/ARC-5 to the AN/ARN-9 USN Air-Track ILS. (The AN/ARN-9 is the ILS that is mentioned in several places in the LF/MF/HF AN/ARC-5 Maintenance Handbook.  It was abandoned in 1944 in favor of the USAAF SCS-51 ILS. )  The MX-19 is not rare, but it has no other use than with AN/ARN-9.  There is no SCR-274-N equivalent. 

MX-20/ARC-5 Power Adapter:  This supplies 24 and 250 vdc to accessory systems like AN/ARR-1, O-4/ARC-5, LM-* and works with any AN/ARC-5 receiver except R-28.  It is equivalent to FT-310-A in SCR-274-N.  It was factory supplied with R-24/ARC-5 to supply power to the associated AN/ARR-1 ZB-homing adapter.  Both the R-24/ARC-5 and AN/ARR-1 were abandoned by USN, replaced by R-4*/ARR-2 ZB-homing receiver. 

MX-21/ARC-5 Remote Control Adapter:  Blank panel that routes 24 vdc for remote control when local control adapter panel is not installed.   It is equivalent to FT-230-A in SCR-274-N.  It was factory supplied with all AN/ARC-5 receivers except R-24/ARC-5 and R-28/ARC-5. 

C-24/ARC-5 Local Control Adapter:  Provides local power/emission switch and RF Gain control.  There are NO audio jacks.  It is equivalent to FT-260-A in SCR-274-N. 

SUMMARY:  The R-23*/ARC-5 receiver was factory supplied with the MX-21/ARC-5 remote control adapter, but it may be found with the MX-20/ARC-5 power adapter instead.  Plastic cover CW-4/ARC-5 for the loop antenna switch spline was supplied from the factory with R-23* and R-24/ARC-5.

Mike / KK5F

-----Original Message-----
From: Mark K3MSB <mark.k3msb at gmail.com (mailto:mark.k3msb at gmail.com)></mark.k3msb at gmail.com (mailto:mark.k3msb at gmail.com)>
Sent: Dec 26, 2023 6:42


I've a question on the HB local remote switch. I believe the real cover has a jack with the cover labeled CW-4 ?? This is what I've seen on web pictures of other R-23 receivers, yet Figure 6-2 of the previously mentioned AN/ARC-5 manual seems to show a different connector MX-20/ARC-5 power adapter ?

73 Mark



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