[Milsurplus] RT-70/GRV

[Morrow, Michael A.]

Jeff N2LXM wrote:

> Well another find in the Garage sale stuff. It's a=20
> RT-70/GRC( part of the ANV/VRC-7 setup)...=20
>
> Does anyone have a copy of the hook up pin outs for
> Power, RX Audio, TX Audio, and PTT.  A schematic would
> also be nice.

Jeff, in case no one has yet provided this info:

Audio Connector
Pin     Function
A - Receiver Audio Out
C - Mic (carbon) Audio In
F - Mic PTT (ground to key)
J - Same as pin E on power connector.
B, E, H - Ground

Power Connector
Pin     Function
A - Receiver Audio Out
B - Relay power (6.3 vdc, 160 mA on transmit)
C - Mic (carbon) Audio In
D - Ground
E - AM-65/GRC HV regulator tube ground return
    (When the RT-70 is used with the AM-65,
     pin E must be connected to ground
     (pin D) at the connector, to ground the
     regulator tube cathodes in the AM-65.  The
     CX-1213/U interconnection cable assembly
     between the RT-70 and the AM-65=20
     has these pins connected internally.  This
     interlock prevents the tubes from drawing
     current when no RT-70 is connected.)
F - Filament power (6.3 vdc, 360 mA)
H - Last stage audio HV power (90 vdc)
J - HV power (except last audio stage) (90 vdc)
    (Total HV current for pins H and J is 80 mA.)
K - Mic PTT (ground to key)

You can connect to everything you need through just the power connector =
alone.
Connect +6.3 vdc to pins B and F, and +90 vdc to pins H and J.

Fair Radio has the individual power connectors cheap.

Verify your address is good at QRZ.com and I'll send a schematic.  =
Verify that V-106 (marked on chassis) is a 1R5 and not a 3A5 so I can =
send the best version.  All RT-70A units had a 3A5 at V-106, and some =
RT-70 (non-A) units had a MWO performed to install a 3A5 at V-106.

I like these 50s-vintage sets.  They were really quite advanced when =
they first arrived on the scene.  I've got the most elaborate system =
that used the RT-70, the AN/GRC-7.  I love all 225 pounds of it.  I've =
also got the simplest configuration, the AN/VRC-7 that you mentioned.

73,=20
Mike / KK5F
  =20