[R-390] Receiver flavors.

[Les Locklear]

You might want to take a few steps back and read the January 2006 issue of Electric Radio magazine Issue No. 200. It tells the "REAL" story of the R-725.

Les Locklear


----- Original Message -----
From: Roger Ruszkowski <flowertime01 at wmconnect.com>
Reply-To: Roger Ruszkowski <flowertime01 at wmconnect.com>
To: <r-390 at mailman.qth.net>
Sent: 7/25/2020 3:58:00 PM
Subject: [R-390] Receiver flavors.
________________________________________________________________________________

Fellows.
The R390A with the R390 IF deck was for a direction finding system.The Antenna array was 20 feet high whips in a 200 foot ring.It all went with a 10 x 20 mobile building.Two operating positions and 4 receivers.The Antenna commutater just spun and an antenna couplerput the signal to all four receives. You tuned up your signaland read the direction for peak signal off a scope face.The horizontal sweep on the scope followed the commutater compass angle
Audio from other locations was wired into the operation positionsand the operator could compare the incoming signal on the audiowire to what was being tuned by the direction finding receiver.The Map analysis would lay it all out from points half way around the world. We could locate an active antenna to betweentwo post.
The hum of the mechanical switching of the antennas caused the mechanical filters to do spurious things.
Some one thought the R390A IF sucked and the R390 IF was better.So some one with contract money found a way to get some built.Just for show and tell of their own power.
R390A with the extra externals.The VFO first and second crystal oscillators were monitored externally.The three oscillators were counted and summed. If the number in the counter was wrong, the stepper drive motor on the VFO shaft,would roll down ten, and then roll back up to the desired frequency.No one knew what the gear train lash was, but they knew howdial an oscillator to frequency with a stepper motor. 
This system was all about finding your exact transmitting frequency.Five racks of equipment and we would call it a Radio Shack CB scanner.
The R390 is a receiver, simply tune it to the desired frequency of maximum signalstrength. You need to drive the gear train to the receiving frequency any way.
The oscillators were counted and the VFO adjusted.The mega hertz and kilo hertz shaft had sprockets and chain drive from the stepper motors mounted in the rack under the receiver.

In the world of 6C4 mixers, where does the external synthesizer give a lower background noise out of the mixer compared to a 6C4 mixer driven with a clean sine wave. This is open design, tweak the R390 6C4 circuits if you expect improvementscan be realized.  You do not need everything the receiver is capable of to get the job done.
A feature of the scanner took the 455 IF off the back of the receiver to a separate detector unit. The ability to set a receiver to a telemetry frequency watch the Doppler shift, and keeping the receiver on maximum signal strength of a changing frequency with the stepper motors was an automation of telemetry collection.
The process started to track battery powered transmitters with no frequency stability.Who knew it would be needed to follow rockets? With one hand on the knob you hadto stick the dits, because the mill needed two hands. Copy on these field units wasa real pain.
Start with a wide band frequency converter to HF. Monitor it with and R390 and run it out to a tape recorder with ready, record, and stop. The external detectors on a T1 phone line band width of rocket stage telemetry would keep the receiver peaked to maximum signal strength. 16 K band width of digital MODEM modulation.
So a better computer, the stepper motors and receivers with oscillator test points were coupled to yet another external detector for the space industry doing regular science.The idea of a transmission that moves across a bandwidth greater than 16 K hertzand needs auto tuning not auto stepping had arrived.That whole RF gear train needs to move not just the count of the oscillator.
If you need exact phase match, you synthesis the match frequency between 455 KHzand DC external to the R390 link in the conversion system.Engineers put their goodies in their own box for profits.Engineers are not known for community service grants.There is room in a rack for that.
Real parts on counter top equals real dollars in Fridays paycheck.I see this part in the military inventory, may I included it in my system design?Find a standard part and it is free to your project design.A good working R390 in any variant is free and you can keep it working good.You want an R390 rebuilt there go your contract dollars.You build your own box of system glue and earn the development dollars for your self.If any of the services need telemetry from a speeding bullet with Doppler, this R390 variant is the off the shelf solution. Just because you do not know it does not mean itdoes not already exist.
The Navy had three separate field modifications to the receivers. Power cord change, front panel pin jack for the DC Load, 1/2 watt out on the line audio. ASA added the micro dial to copy RTTY.Signal Corp added the dial cover because receivers were often on public display while in use.Navy added red dial lamps. Blue lamps were also available.After thatif someone wanted something else, ask a company to rework some number of receiversand get them up to spec for their intended project use. TMC did lots of work building one offsystems for a series of space contracts. Hughes Ground Systems Group was all about the land base end of communication systems.
The Chinese are tracking the mass of Earth down to the size of an oil barrel.They are working on mass down to the size of a pork belly.They want to track mass down to the size of a virus. The Chinese integrated circuit factories are two production generations behind Japan.Chinese chips will not do 5 G.The network chips for 5 G are fabricated in Japan for Huawei China phones.Hackers claim "diagnostic" firm ware processed into the chips during manufacturingis the phone spy engine part of 5 G. The service provider can track the phone. Where are my company phones and my employees?A new phone feature for a fee.China trashed Japans summer Olympics accident or not.
The chip fabricator in Japan said it will end the production and export of spy phone chips to Chinawhen the contract ends on 31 August 2020.
Can you request a GE locomotive train engine for a crash test?Yes Hughes did it first, and if some one else hasa contract item to repeat the test you willbecome the proud new owner of a used once train engineto care for until a third owner of the engine is designated.There is more than one way to get creativity off on a siding.
Your tax dollars providing safe daycare to nerds.
Do not run into kitchen.
Roger 33C4H AI4NI 




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