[ARC5] which modules?

[Mike Everette via ARC5]

The SCR-274N transmitter control box (BC-451) has mic and key jacks, plus the little built in "key" on top.  


However, the BC-456 modulator for the 274N has no mic and key jacks on the chassis.

The C-29/ARC-5 "equivalent" to the BC-451 has no mic jack. key jack, or built in key; however, the MD-7/ARC-5 modulator has mic and key jacks on the chassis apron.  It also has an extra connector to work with "other equipment" (interphone etc) which has mic, key, and side tone available.

It IS possible to "miscegenate" an ARC-5 with 274N components, i.e. use a 274N control box with an MD-7; but you would lose the "test key" function in the ARC-5 transmitter racks.  The MD-7 has an extra relay which works with the test key function, to isolate the transmitter being tested from the selector switch in the control box.

In order to do this crossbreeding, you'd need a connector on one end of the control box cable to fit the MD-7 and on the other to fit the BC-451.  They are different.  The difference is the physical location of the number #1 pin.  You could drill a hole in a 274N control connector so it would mate with the MD-7 (or the C-29) but you would not have the number #1 channel select function which is on the #1 pin.


Actually, the MD-7 modulator does have the mic audio and key lines available at the connector going to the control box; there's just nothing in the box to use them.

To take the crossbreeding further, you can also use ARC-5 racks with a BC-456 modulator, or 274N racks with an MD-7, as long as you have the proper connectors on either end of the cables.  If you're using an ARC-5 rack with other 274N components, you will not be able to use the test key function.

How to wire all this up?

Check out the 274N and ARC-5 manuals on BAMA and compare the system diagrams; it's not really rocket science.

A physician who was a ham and the father of one of my high school ham friends said:  "ARC-5 Fever is a disease for which there is no cure..  It may go into remission, but always comes back."


73

Mike
WA4DLF




On Wednesday, June 25, 2014 5:06 PM, WA5CAB--- via ARC5 <arc5 at mailman.qth.net> wrote:
 


More than "somewhat", I would wager!

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480

In a message dated 06/25/2014 07:40:03 AM Central Daylight Time, 
aaf-radio-1 at aafradio.org writes: 
> >   I am looking forward to retirement so I will have the time to "do" 
> this hobby!
> 
> If you are counting on that, then you may be somewhat surprised...:-D
> 
> 73,
> Mike
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