[Milsurplus] [ARC5] Soviet 1RSB-70 copy of the AN/ARC-8, Plus Other TU-4 Radio Sets

[Mike Morrow]

Meir wrote:

> I also think, based on a lot of evidence, that the RSB-70 (not 1RSB-70), and
> the US-9 were not reverse engineered copies of the original items, but they
> must have gotten the plans which they have subsequently modified to conform
> to their available parts, manufacturing processes and standards.

I think that this is exactly what happened.  It is clear that the 1RSB-70 is
patterned very closely on the early USN ATC, not the later USAAF T-47A/ART-13.
BTW, my 1950 Tu-4 radio manual refers in *every one* of hundreds of reference to
the "1RSB-70" as both the nomenclature for the whole MF/HF liaison set system
(including the US-9 receiver) *and* and for the transmitter itself.  

> ...I've never seen the first production run RSB-70 which, as you mentioned,
> has the TCZ type rails.

TCZ rails are the same as early ATC mounting rails, for which the stationary
part received the JAN MT-161/ART-13 designation.

> My R-807 has the same type rails as the ART-13, although mechanically they're
> mounted differently - not as part of the bottom tray, but individual rails.
> With this said, the R-807 very happily fits the ART-13 shock mount.

The JAN nomenclatures for these types are MT-283/ART-13 for the movable part
(mounted on bottom of transmitter) and MT-284*/ART-13 for the stationary part
(mounted on aircraft).  I suppose that the Soviet versions better suited
their needs.  Is the right-side mount interchangeable with the left-side?

> My R-807 came with the original calibration book.

You sent me years ago a copy of a page from that.  IIRC, the tabulated data
for any one frequency was close, but not exactly the same, as that shown in
the US equivalent.  It was provided only in 5 or 10 kHz increments, unlike
the 1 kHz increments possible with the VFO dial B vernier scale found on
the T-47A/ART-13.

Some questions about the R-807:

(1)  Does it still use the original two-tube 8Q-1 style MCW-CFI unit?
(2)  Does it have the LF/MF oscillator, and if so is it the ATC-style
     200 to 1500 kHz unit, or a 200 to 600 kHz O-17/ART-13A style unit? 

> In the original Russian R-807/US-9 system the key used was a special key,
> model P31V (П31В) which has a transmit/receive switch.

The key pictured in the 1950 Tu-4 radio manual appears to be identical to the
US J-37 key.

> Regarding the US-9: again, I wasn't aware that the earliest models didn't
> have the 28V line fuse on the front panel and the regulator was a neon bulb
> like in the BC-348(*). I bet the knobs even on that model weren't aluminum
> like the BC-348, but plastic, like on the later production runs.

It's hard to tell from the manual's photographs...the smaller knobs are styled
differently from the BC-348's, but the main dial tuning knob appears identical
to that of the BC-348-*.

> There is another improvement over the BC-348: the dynamotor base plugs into
> the receiver chassis via a Jones-type plug and socket system.

The schematic of the early US-9 seems to show a terminal exactly like that
on the BC-348-H/K/L/R.  I'd expect that, for other than the AF output tube
being a 6V6 (with associated filament resistor alteration), the early US-9
seems electrically and mechanically identical to the BC-348-H/K/L/R.

I'll send you (and anyone else interested) an eight-page pdf of scans of
several pages from my Tu-4 radio manual that deal with the 1RSB-70 and the
US-9.  It'll be under a separate e-mail, and is 5 MB in size. 

73,
Mike / KK5F