[R-390] R390/URR manuals

[Todd, KA1KAQ]

On Tue, Mar 8, 2011 at 8:49 AM, Michael, W1RC <subs at w1rc.net> wrote:

> As timing would have it right now I am working on an R-390 and need
> to know if anyone has the Field Change Orders.  Specifically I need
> some information contained in both C1 and C3.  There is a "Zero
> Adjustment" caution that I would like to see.  I am just about to
> remove the front panel and there is a handwritten notation in my
> TM11-5820-357-35 that I should see these items.
>
> If anyone has C1 and/or C3 would you be so kind as to post these
> cautions.  I haven't played much with these radios for about 13 years
> and I don't want to damage anything by virtue of forgetfulness.


I don't have those Mike, but here's the later 1962 TM info I have
saved for my ex-ASA 390 (both changes are stenciled on front):

MWO-11-5820-294-35/1

>From Change 4 of TM 11-856, TO 31R1-2URR-154, dated 22 Dec 1958:

" In receivers modified by MWO 11-5820-294-35/1, the wires connected
to B+ 3/8A Fuse F102 are
removed and tied together, and the ground connection on transformer
T801 is removed. There is no
connection between the DC 20A Fuse F103 and P118-15 (not applicable to
Fig 53 of TM), and Terminal
6 of T801 is connected through the contacts of J818-15 and P118-15 and
B+ 3/8A Fuse F102 to ground.
The B+ 3/8A Fuse is called the HV 3/8A Fuse.

Power Supplies PP-621/URR modified in accordance with MWO
11-5820-294-35/1 are NOT
interchangeable with power supplies that are not so marked because of
wiring changes in the B+ 3/8A
Fuse F102 circuit.

R-390/URR Receivers modified by MWO -35/1 above have the former B+
3/8A Fuse F102 in the
ground lead of power transformer T801 and the name of the fuse is
changed to HV 3/8A.

The MWO -53 35/1 supersedes MWO SIG 191 dated 20 July 1955 and
contractor changes on Power Supplies PP-
621/URR identified as MOD 1 and above.

These changes restore interchangeability between Power Supplies
PP-621/URR and permit their being used in all Radio Receivers
R-389/URR, R-390/URR, and R-391/URR so modified.

In receivers modified by MWO -35/1 above the B+ 3/8A Fuse F102 is NOT
connected between P120-5
and +300V Unregulated.

In power supplies modified by MWO -35/1 above there is NO connection
between Terminals 10 (Ten)
and 6 (Six) of T801; There is a wire connected between Terminal 6 of
T801 and Terminal 15 of J818.
On Receiver Main Frames modified by MWO -35/1 above, ( TM Fig.106)
Station 35 Wire 1-33 is 7-40,
Wire 5-41 is 15-41 and B+ is HV . At Station 37 there is NO Wire
15-41. At Station 41 there is a wire
added between the cable and Terminal 1 of C101 labeled 5-41, change
Wire 35-1 to 42-2, and Wire 37-2
to 35-1. At Station 40, add a wire between Terminal 7 and the cable
labeled 35-2."



MWO-11-5820-294-35/2

URGENT
MWO 11-5820-294-35/2

DEPARTMENT OF THE ARMY MODIFICATION WORK ORDER
MODIFICATION OF RADIO RECEIVERS R-390/URR AND R-390A/URR TO ELIMINATE
SPURIOUS RADIATION.

PARAGRAPH 1. Application.

a. Applied to. All Radio Receivers R-390/URR and R-390A/URR bearing
orders no. 14225-P-51,
14214-P-51, 90-P-52, 26579-P-52, 13602-P-53, 363-P-54, 375-P-54,
08719-P-55, 0014-P-56, R56-881-
67058, or 14385-PC-68.

b. Category of maintenance.
(1) Field. This work order will be applied by third echelon
maintenance personnel.........
history and misc notes page 30

(2) Depot. This work order will be applied to Signal Corps depot stock by depot
maintenance personnel only when equipment is--

(a) Undergoing scheduled repair for stock.
(b) Subject to other work orders that require application prior to issue.


c. Applied By. Field Radio Repairman or equivalent maintenance personnel.
PARAGRAPH 3. Purpose of Modification To eliminate continuous radiation
at 340 mc as a
result of parasitic oscillations, by connection the suppressor grid to
the cathode of the local
audio output tube V603.

PARAGRAPH 10. Modification Procedure.
a. Radio Receiver R-390/URR.

(6) Unsolder and remove the jumper lead connected between pin 2 and
ground of tube socket
XV603.

(7) Connect and solder a suitable length No. 22 AWG solid wire between
pins 2 and 7 of tube
socket XV603.

b. Radio Receiver R-390A/URR.

(4) Unsolder and remove the jumper lead connected between pin 2 and 4
of tube socket XV603.

(5) Connect and solder a suitable length No. 22 AWG solid wire between
pins 2 and 7 of tube
socket XV603.

11. Recording the Modification. Ink or paint "MWO 11-5820-294-35/2"
near the nomenclature
plate on the front panel of each modified receiver. When modified
equipment is packed or
crated, clearly mark "MWO 11-5820-294-35/2" on the exterior of the
case in a similar manner.



And a handy breakdown of the MWO structure:

MWO is a Modification Work Order.

11-5820 is a electron tube device (Radio)

11-5820-294 may be a version of the R390 or R390/A manual.

11-5820-294-35 tells us its a 3 to 5 level maintenance manual.

11-5820-294-35/2 tells us its the second change against the unit.

Field changes being MWO applied after manufacture. As opposed to MWOs
applied in the
factory after some units are built. The 3 fuse model of the R390/A is
a factory MWO. You did not
refit the receivers that were build and fielded. The adjustable
trimmer caps on the mechanical
filters is another factory MWO.

Field MWOs included:

Micro Dial on BFO for ASA

Re-cabling the antenna relay to use the C connector

Diode mod to replace the 26Z5's.



Think I got some of this from Rich McClung and another list member a
decade back, perhaps. Wonder how ol' Rich is doing these days?

de Todd/'Boomer'  KA1KAQ/4