[R-390] Re: R-390 Digest, Vol 4, Issue 6

[Bernie Nicholson]

Talking about better radios than the 390a ,Afew years ago I aquired a WRR2
by national ,Now there is what I think is the penultimate Valve reciever
,Sorry for you guys in the US  ,TUBE reciever I would say that it was a
product of the early sixties and synthasized in 500 hz steps and in 2 boxes
that are both heavier than a 390a  and also 2 channel  ISB capability
also -, The biggest Radio reciever  I have -owned was made by the technical
material corp and weighed in at more than 500pounds and also had a crystal
controlled synthasizer and the radio was capable of 4 channel ISB  it
completly filled a 7Ft rack and the house lights used to dim when I turned
it on.  regards to everyone on the site --- Original Message -----
From: <r-390-request at mailman.qth.net>
To: <r-390 at mailman.qth.net>
Sent: Sunday, August 08, 2004 12:40 PM
Subject: R-390 Digest, Vol 4, Issue 6


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> Today's Topics:
>
>    1. Re: Ovens and Synchronization (Bob Camp)
>    2. Re: Halloween Set (Bob Camp)
>    3. Re: Halloween Set (Michael Murphy)
>    4. Re: Russian HF Radios (Bob Camp)
>    5. RE: Russian HF Radios (WF2U)
>    6. Birthday please (Richard May)
>    7. Re: Russian HF Radios (Bob Camp)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sat, 07 Aug 2004 18:20:08 -0400
> From: Bob Camp <ham at cq.nu>
> Subject: Re: [R-390] Ovens and Synchronization
> To: Cecil Acuff <chacuff at cableone.net>, R-390 HF Receiver List
> <r-390 at mailman.qth.net>
> Message-ID: <F0AAD4FE-E8BF-11D8-917B-000A95C4FE54 at cq.nu>
> Content-Type: text/plain; charset=US-ASCII; format=flowed
>
> Hi
>
> The crystal ovens in the R-390 and the R1051 are different beasts. The
> 1051 oven standard is designed like a modern OCXO. The crystal inside
> it is cut so it is very stable at the oven operating point. The oven in
> the 1051 is designed so it is very temperature stable.
>
> Unfortunately none of this is true of the crystal oven in the R390
> series of radios. From talking to the guy who did the design of that
> part of the radio it was known to be a stop gap solution at the time.
> The main reason for it's inclusion was a requirement for modest
> stability at temperatures well below freezing.
>
> The crystal oven in the R390 swings in temperature over something like
> a 10 degree C range in normal operation. A fairly normal room should be
> stable within a degree or two for quite a while. Since the oven cycle
> time is in tens of minutes the oven is definitely a poor choice for
> basic temperature stability.
>
> The crystals in the R390 are not specifically cut for oven operation.
> This is a good thing since we don't turn the ovens on. In order to
> optimize them for an oven environment you cut the crystal so it's upper
> turn temperature is approximately at the oven temperature. Since there
> is a tolerance on the cutting process it is hard to do anything more
> than get them close to the oven temperature.  When you cut the crystals
> this way a side effect is to make their performance at room temperature
> worse than a normal crystal.
>
> The oven on the PTO is kind of the same thing. It does not cycle over
> quite as wide a range as the crystal oven, but it does cycle further
> than your room probably does. The issue with the PTO is coil form
> shrink. The hotter you run the PTO the faster the master coil shrinks.
> Eventually the coil shrinks enough that you can no longer get the PTO
> on frequency with the correction adjustment. There is an article in
> Electric Radio back a few years that goes into all this stuff. Strange
> but true I worked for the guy who is quoted in the article. At the time
> I worked for him he would just barely admit working on the PTO's ....
>
> Finally, when you turn on the ovens on the R-390 you almost double the
> power in the radio. The oven in the R1051 is not as big a power hog as
> the ovens in the R390. When the heat in the radio goes up by that much
> the whole radio will get hotter. Unless you run some kind of fans to
> cool everything the result will be parts that run hot and wear out
> faster. Of course the fans would cool off the ovens which draws more
> power which heats up stuff more ... nasty cycle.
>
> One note - The ovens we are talking about are the ones on the crystal
> oscillator deck and inside the PTO. The plug in oven that has the
> calibrator crystal in it does not get turned off by the "oven on/off"
> switch. The plug in oven does do a good job, it does not pull a lot of
> power and it should be left running.
>
> One of the neat things you can do with a bunch of R390's (like say you
> just picked up a dozen of them ...) is to sort the crystals in the
> crystal oscillator deck. The closer you get to a matched set of
> crystals the less you will have to adjust the radio each time you
> change bands. I still think  they should have put tuning caps on the
> crystals. The reason they didn't : " Well we didn't do it because it
> wasn't in the spec". Darn Ft. Monmouth.
>
> Take Care!
>
> Bob Camp
> KB8TQ
>
>
>
> On Aug 7, 2004, at 5:14 PM, Cecil Acuff wrote:
>
> > Hey guys,
> >
> >         Lets talk about the crystal ovens in the 390A.  I seem to
> > remember
> > it is common practice to not use them anymore for the sake of
> > longevity.
> >
> > My R-1051 experience is that one can't do without the oven in the
> > Frequency
> > Standard because without the oven the stability the 1051 is known for
> > goes
> > down the toilet.  The crystal in the oven was designed to work at a
> > specific
> > temp to be stabile.  There is a nice flat spot in the curve up around
> > 85C
> >
> > Is this not the same with the crystal deck, calibrator xtals and maybe
> > to a
> > lesser degree the PTO in the 390A?
> >
> > Looking in the Y2K manual it seems recommended to fire them up a few
> > hours
> > before an alignment but then go back to the practice of turning them
> > off for
> > our day to day ops....seems that would negate the alignment.  Wouldn't
> > one
> > be better off doing the alignments in the state one would normally
> > operate
> > the radio?
> >
> > I am at the point in my R-390A ownership that I am starting to get
> > technical
> > with the 390A now that time presents that opportunity.  As a result I
> > guess
> > I'll be asking some of the typical beginner questions.
> >
> > Coming to a post near you:  How does one go about putting a radio back
> > together where everything is totally out of mechanical and electrical
> > sync!
> >
> > I pulled the whole IF deck apart for complete cleaning....4 years ago.
> >  No
> > problem on getting everything back together just need some starting
> > point
> > for getting everything re-synchronized.  It was a nasty blue
> > striper...won't
> > know it once it's complete....it cleaned up very nicely.  The gear
> > train is
> > separated from the IF deck chassis and all that is separated from the
> > xtal
> > deck.
> >
> > Gear train works like a swiss watch....love that Mobil 1
> >
> > Thanks in advance!
> >
> > Cecil Acuff
> >
> >
> > ______________________________________________________________
> > R-390 mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/r-390
> > Help: http://mailman.qth.net/faq.htm
> > Post: mailto:R-390 at mailman.qth.net
> > Unsubscribe: http://mailman.qth.net/mailman/options/r-390
> >
>
>
>
> ------------------------------
>
> Message: 2
> Date: Sat, 07 Aug 2004 18:33:31 -0400
> From: Bob Camp <ham at cq.nu>
> Subject: Re: [R-390] Halloween Set
> To: Commtekman at aol.com, R-390 HF Receiver List <r-390 at mailman.qth.net>
> Message-ID: <CF360A9F-E8C1-11D8-917B-000A95C4FE54 at cq.nu>
> Content-Type: text/plain; charset=US-ASCII; format=flowed
>
> Hi
>
> Main power to the radio is controlled by a microswitch ganged to the
> function switch shaft. It is fairly common for this little item to weld
> it's self in the on position. Last time I had a problem with one of
> these I got the parts from somebody on the list. It was either David
> Medley or Hank. The fix is not to hard except you have to unmount the
> front panel to get at the switch. It's a little time consuming is all.
> When you mount the new one you want to make sure it's snug on the mount
> so it goes full on / full off. If it gets loose it may weld again.
>
> The flashing is a bit odd. Other than the heater thermostat in the
> crystal oven I can't think of anything in the pilot light circuit that
> would cycle. You may have a bad wire from the power transformer to the
> filaments. It's P111 / J111 in the Y2K manual. You might also make sure
> the "ovens" switch on the back of the radio is set to off.
>
> Everything about these radios is fixable. I do not know of any parts
> that are in the "can't get or replace them" category. Dive on in and
> see what's wrong. They were designed to be repaired.
>
> Enjoy!
>
> Bob Camp
> KB8TQ
>
>
>
> On Aug 7, 2004, at 5:42 PM, Commtekman at aol.com wrote:
>
> > Hey Guys-
> > In one of my 'senior moments', I bought an R-390 off of Eplace, finally
> > received it, powered it up without turning it on, all the tube
> > filaments came on
> > while it was still in the 'off' position, and the dial light started
> > flashing
> > like a haunted house on halloween night. I suspect without going
> > further that
> > this has something to do with the standby or break-in being held up
> > and not
> > releasing. Ideas?
> > Tnx Bob
> > K6OSM
> > Mccall, Idaho
> > ______________________________________________________________
> > R-390 mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/r-390
> > Help: http://mailman.qth.net/faq.htm
> > Post: mailto:R-390 at mailman.qth.net
> > Unsubscribe: http://mailman.qth.net/mailman/options/r-390
> >
>
>
>
> ------------------------------
>
> Message: 3
> Date: Sat, 7 Aug 2004 18:41:56 -0400
> From: "Michael Murphy" <mjmurphy45 at comcast.net>
> Subject: Re: [R-390] Halloween Set
> To: "Bob Camp" <ham at cq.nu>, <Commtekman at aol.com>, "R-390 HF Receiver
> List" <r-390 at mailman.qth.net>
> Message-ID: <003501c47ccf$be69dd60$6600a8c0 at comcast.net>
> Content-Type: text/plain; charset="iso-8859-1"
>
> No Bob, Don't get going on the micro switch! That could be worse than the
> ballast blast.  Mike WB2UID
>
> ----- Original Message -----
> From: "Bob Camp" <ham at cq.nu>
> To: <Commtekman at aol.com>; "R-390 HF Receiver List" <r-390 at mailman.qth.net>
> Sent: Saturday, August 07, 2004 6:33 PM
> Subject: Re: [R-390] Halloween Set
>
>
> > Hi
> >
> > Main power to the radio is controlled by a microswitch ganged to the
> > function switch shaft. It is fairly common for this little item to weld
> > it's self in the on position. Last time I had a problem with one of
> > these I got the parts from somebody on the list. It was either David
> > Medley or Hank. The fix is not to hard except you have to unmount the
> > front panel to get at the switch. It's a little time consuming is all.
> > When you mount the new one you want to make sure it's snug on the mount
> > so it goes full on / full off. If it gets loose it may weld again.
> >
> > The flashing is a bit odd. Other than the heater thermostat in the
> > crystal oven I can't think of anything in the pilot light circuit that
> > would cycle. You may have a bad wire from the power transformer to the
> > filaments. It's P111 / J111 in the Y2K manual. You might also make sure
> > the "ovens" switch on the back of the radio is set to off.
> >
> > Everything about these radios is fixable. I do not know of any parts
> > that are in the "can't get or replace them" category. Dive on in and
> > see what's wrong. They were designed to be repaired.
> >
> > Enjoy!
> >
> > Bob Camp
> > KB8TQ
> >
> >
> >
> > On Aug 7, 2004, at 5:42 PM, Commtekman at aol.com wrote:
> >
> > > Hey Guys-
> > > In one of my 'senior moments', I bought an R-390 off of Eplace,
finally
> > > received it, powered it up without turning it on, all the tube
> > > filaments came on
> > > while it was still in the 'off' position, and the dial light started
> > > flashing
> > > like a haunted house on halloween night. I suspect without going
> > > further that
> > > this has something to do with the standby or break-in being held up
> > > and not
> > > releasing. Ideas?
> > > Tnx Bob
> > > K6OSM
> > > Mccall, Idaho
> > > ______________________________________________________________
> > > R-390 mailing list
> > > Home: http://mailman.qth.net/mailman/listinfo/r-390
> > > Help: http://mailman.qth.net/faq.htm
> > > Post: mailto:R-390 at mailman.qth.net
> > > Unsubscribe: http://mailman.qth.net/mailman/options/r-390
> > >
> >
> > ______________________________________________________________
> > R-390 mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/r-390
> > Help: http://mailman.qth.net/faq.htm
> > Post: mailto:R-390 at mailman.qth.net
> > Unsubscribe: http://mailman.qth.net/mailman/options/r-390
>
>
>
>
> ------------------------------
>
> Message: 4
> Date: Sat, 07 Aug 2004 19:25:17 -0400
> From: Bob Camp <ham at cq.nu>
> Subject: Re: [R-390] Russian HF Radios
> To: Forrest Myers <femyers01 at bellsouth.net>, R-390 HF Receiver List
> <r-390 at mailman.qth.net>
> Message-ID: <0AA50B0E-E8C9-11D8-917B-000A95C4FE54 at cq.nu>
> Content-Type: text/plain; charset=US-ASCII; format=flowed
>
> Hi
>
> Well I seem to remember they made a receiver called the R320 that was
> intended as a dedicated intercept radio. I have been able to find very
> little information on the radio and have never seen one. What little I
> was able to find claims it was a bit large (a couple hundred pounds)
> but worked quite well.
>
> Enjoy!
>
> Bob Camp
> KB8TQ
>
>
> On Aug 7, 2004, at 5:59 PM, Forrest Myers wrote:
>
> > Well,
> >  If the Russians copied an r-390 non A they may have made a better all
> > tube
> > hf radio than the r390-a, hee hee.
> >
> > Forrest Myers
> > AG4ND
> >
> >
>
>
>
> ------------------------------
>
> Message: 5
> Date: Sat, 7 Aug 2004 22:01:12 -0400
> From: "WF2U" <wf2u at starband.net>
> Subject: RE: [R-390] Russian HF Radios
> To: "Bob Camp" <ham at cq.nu>, "Cecil Acuff" <chacuff at cableone.net>,
> "R-390 HF Receiver List" <r-390 at mailman.qth.net>
> Message-ID: <NABBLNEJDDKECLKHCAAPGEGBKFAA.wf2u at starband.net>
> Content-Type: text/plain; charset="iso-8859-1"
>
> The Russians indeed built a receiver in the same class and purpose as the
> R-390 and R-390A. The frequency display was not the Veeder-Root
> mechanical-digital counter as in the R-390* series, but an analog system
> comprised of a coarse dial displaying each 2 MHz band  in 100 KHz
increments
> and a "fine" frequency dial which was projected from the rear, displaying
> increments of  1 KHz, above the coarse dial. The receiver has  a dual
> conversion system based on a tunable first IF of  1.5 to 3.5 MHz, mixed
down
> to  the 215 KHz fixed IF. The rest of the bands are converted with a
crystal
> oscillator/mixer to the variable IF, a la Collins. The difference is that
> the bands are 2 MHz wide instead of the 1 MHz in the Collins system, and
the
> tuning is not a permeability tuning arrangement with slugs moving in and
out
> of the coils, but a multi-section main tuning capacitor and a drum
> bandswitch system. The selectivity is infinitely adjustable (by variable
> coupling of the 215 KHz IF stages, between 1 KHz and 14 KHz, and an audio
> bandpass filter is provided as well, selectable between 8, 5, 2.5 and 0.3
> KHz.
> The receiver contains a thermostat-controlled ovenized crystal calibrator,
> the BFO is tuned with a reduction drive, with a dial displaying   -5 KHz -
> 0 - +5 KHz frequency in  100 Hz increments. AGC time constants available
are
> 1, 0.1 and 0.05 seconds or AGC OFF.
> The RF input is selectable with a front panel switch  between a 60 to 400
> ohm (nominal), balanced and unbalanced dipole, whip/long wire or ground,
> antenna  trimmer control on the front panel.
> There are jacks for AGC in/out for diversity, 1st and 2nd IF out, and 600
> ohm audio line out (besides the headphone jacks).
> The construction is modular: the RF/first IF/crystal oscillator/mixer is
in
> the bottom drawer in the cabinet, the top drawer contains the second IF,
> BFO, AGC, detector and audio circuits, as well as the metering circuit -
the
> receiver has a built-in emission tester and each tube can be selected for
> test while the receiver is in operation, or the meter can be switched by
the
> selector to monitor the audio line output or the received signal strength.
> The power supply is external, and interestingly the input is selectable
> between 220 and 120 VAC...
>
> The first version of this receiver was put in service with the (former)
> Soviet Armed Forces in 1948 with the military nomenclature of R-250
> ("Whale"), and the improved version, the R-250M was issued in the early
> 1950's. Both these models used standard metal octal tube types, which are
> equivalent to the US types. In the early 60's the receiver was modernized
> and standard miniature tubes were used together with some circuit
> improvements. The self testing arrangement got an additional feature, a
> built-in noise generator, so besides emission testing of the tubes, a
> sensitivity check could be performed without external test equipment
(like:
> "Hey, Sergey, I can't copy headquarters!"  "Check the receiver with the
> noise generator, Ivan!" "click, click, click as the meter switch is turned
> to check each tube, and the input with the noise generator"- "There is
> nothing wrong with the receiver"  "S**t! The ice broke the antenna
again!")
> This version was the R-250M2 and was in production until 1981.
>
> Incidentally, in all these receivers the B+ is 160 VDC, giving the tubes a
> real long and cool life, with a total current draw  of 120 mA!  The
> filaments are series-parallel connected (all 6.3 V tubes) for 12.6 V at 6
A.
>
> I own a pristine R-250M model. Its performance is simply incredible,
> considering an early 50's design with all octal tubes (19 of them). It
> outperforms many receivers 10 years more advanced. The spec on the
> sensitivity is 0.6 uV  for S/N ratio of 10 dB at 3 KHz IF and 2.5 KHz AF
> bandwidth, with a 100 ohm antenna. Audio output is 0.5 W into 600 ohms at
4%
> (AF output tube is a Russian 6P6, which is the exact equivalent of the
6V6).
> Frequency stability is specified as maximum 200 Hz drift after a warm-up
of
> 2 hours!
> The tube complement in US equivalent designations is  10 x 6SK7, 3 x 6AC7,
> 3 x 6SA7, 2 x 6H6, 1 x 6V6, + a voltage regulator tube (I have to find the
> US equivalent) and the power supply has a 5Z4 rectifier.
> The detector/BFO injection is good enough for good SSB reception, even
with
> the AGC on, as well as CW is just great to copy on it with all the
> selectivity options.
> It's no slouch in AM quality, although  .5 W  is really not enough to
drive
> a big speaker without an outboard amp.
>
> All this in a real "boatanchor" package of 26" wide, 18" deep and 21" tall
> (with the shock mounts), weighing 209 pounds, without the power supply,
> which weighs about 35 pounds.
> Options available were RTTY demodulator, high precision AFC (Automatic
> Frequency Control) system, which provides tuning with a servo motor and a
> diversity control interface. There was also a vibrator power supply
option,
> for 12 VDC input.
>
> Construction is really excellent quality and it looks like good US
mil-spec
> work. The wiring and soldering are also first-class, the components look
> high quality. The transformers are potted, cased and painted, just like
the
> US mil. stuff. Incidentally, I got a couple of sets of NOS spare tubes,
with
> 1972 manufacturing date. Pretty late for still making metal octal military
> tubes!
>
> There are photos of the various versions at a Russian web site
> http://www.cqham.ru/trx/r_250.html .
>
> Well, I hope this wasn't boring, but there is not too much traffic here
> tonight anyway...
>
> 73, Meir WF2U
> Gowensville, SC
>
>
>  -----Original Message-----
> From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
> On Behalf Of Bob Camp
> Sent: Saturday, August 07, 2004 5:15 PM
> To: Cecil Acuff; R-390 HF Receiver List
> Subject: [R-390] Russian HF Radios
>
> Hi
>
> Well obviously we need to get something going.
>
> How about did the Russians build a better all tube HF receiver than the
> R-390A? From what I hear the answer may be yes ....
>
> That's the way to see if anybody's listening.
>
> Enjoy!
>
> Bob Camp
> KB8TQ
>
>
> On Aug 7, 2004, at 4:57 PM, Cecil Acuff wrote:
>
> > Test...
> >
> > ______________________________________________________________
> > R-390 mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/r-390
> > Help: http://mailman.qth.net/faq.htm
> > Post: mailto:R-390 at mailman.qth.net
> > Unsubscribe: http://mailman.qth.net/mailman/options/r-390
> >
>
> ______________________________________________________________
> R-390 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/r-390
> Help: http://mailman.qth.net/faq.htm
> Post: mailto:R-390 at mailman.qth.net
> Unsubscribe: http://mailman.qth.net/mailman/options/r-390
>
>
>
> ------------------------------
>
> Message: 6
> Date: Sun, 8 Aug 2004 02:02:47 +0000 (GMT)
> From: Richard May <richardmay at hotmail.com>
> Subject: [R-390] Birthday please
> To: r-390 at mailman.qth.net
> Message-ID: <9762922.1091930567453.JavaMail.Administrator at win02>
> Content-Type: text/plain; charset=us-ascii
>
> Hi
>
> Click on the link below and please enter your birthday for me. It will
take less than 1 minute. I am creating a birthday list of all my friends and
family.
>
>  http://www.BirthdayAlarm.com/dob2/21710769a384025368b142965556c904
>
> Many thanks
> Richard
>
>
>
> ------------------------------
>
> Message: 7
> Date: Sat, 07 Aug 2004 22:37:46 -0400
> From: Bob Camp <ham at cq.nu>
> Subject: Re: [R-390] Russian HF Radios
> To: wf2u at starband.net, wf2u at starband.net, R-390 HF Receiver List
> <r-390 at mailman.qth.net>
> Message-ID: <EED294CD-E8E3-11D8-917B-000A95C4FE54 at cq.nu>
> Content-Type: text/plain; charset=US-ASCII; format=flowed
>
> Hi
>
> So how do you get one of these beasts?
>
> Obviously we need more R390 to R250M2 comparisons.
>
> Take Care!
>
> Bob Camp
> KB8TQ
>
>
> On Aug 7, 2004, at 10:01 PM, WF2U wrote:
>
> > The Russians indeed built a receiver in the same class and purpose as
> > the
> > R-390 and R-390A. The frequency display was not the Veeder-Root
> > mechanical-digital counter as in the R-390* series, but an analog
> > system
> > comprised of a coarse dial displaying each 2 MHz band  in 100 KHz
> > increments
> > and a "fine" frequency dial which was projected from the rear,
> > displaying
> > increments of  1 KHz, above the coarse dial. The receiver has  a dual
> > conversion system based on a tunable first IF of  1.5 to 3.5 MHz,
> > mixed down
> > to  the 215 KHz fixed IF. The rest of the bands are converted with a
> > crystal
> > oscillator/mixer to the variable IF, a la Collins. The difference is
> > that
> > the bands are 2 MHz wide instead of the 1 MHz in the Collins system,
> > and the
> > tuning is not a permeability tuning arrangement with slugs moving in
> > and out
> > of the coils, but a multi-section main tuning capacitor and a drum
> > bandswitch system. The selectivity is infinitely adjustable (by
> > variable
> > coupling of the 215 KHz IF stages, between 1 KHz and 14 KHz, and an
> > audio
> > bandpass filter is provided as well, selectable between 8, 5, 2.5 and
> > 0.3
> > KHz.
> > The receiver contains a thermostat-controlled ovenized crystal
> > calibrator,
> > the BFO is tuned with a reduction drive, with a dial displaying   -5
> > KHz -
> > 0 - +5 KHz frequency in  100 Hz increments. AGC time constants
> > available are
> > 1, 0.1 and 0.05 seconds or AGC OFF.
> > The RF input is selectable with a front panel switch  between a 60 to
> > 400
> > ohm (nominal), balanced and unbalanced dipole, whip/long wire or
> > ground,
> > antenna  trimmer control on the front panel.
> > There are jacks for AGC in/out for diversity, 1st and 2nd IF out, and
> > 600
> > ohm audio line out (besides the headphone jacks).
> > The construction is modular: the RF/first IF/crystal oscillator/mixer
> > is in
> > the bottom drawer in the cabinet, the top drawer contains the second
> > IF,
> > BFO, AGC, detector and audio circuits, as well as the metering circuit
> > - the
> > receiver has a built-in emission tester and each tube can be selected
> > for
> > test while the receiver is in operation, or the meter can be switched
> > by the
> > selector to monitor the audio line output or the received signal
> > strength.
> > The power supply is external, and interestingly the input is selectable
> > between 220 and 120 VAC...
> >
> > The first version of this receiver was put in service with the (former)
> > Soviet Armed Forces in 1948 with the military nomenclature of R-250
> > ("Whale"), and the improved version, the R-250M was issued in the early
> > 1950's. Both these models used standard metal octal tube types, which
> > are
> > equivalent to the US types. In the early 60's the receiver was
> > modernized
> > and standard miniature tubes were used together with some circuit
> > improvements. The self testing arrangement got an additional feature, a
> > built-in noise generator, so besides emission testing of the tubes, a
> > sensitivity check could be performed without external test equipment
> > (like:
> > "Hey, Sergey, I can't copy headquarters!"  "Check the receiver with the
> > noise generator, Ivan!" "click, click, click as the meter switch is
> > turned
> > to check each tube, and the input with the noise generator"- "There is
> > nothing wrong with the receiver"  "S**t! The ice broke the antenna
> > again!")
> > This version was the R-250M2 and was in production until 1981.
> >
> > Incidentally, in all these receivers the B+ is 160 VDC, giving the
> > tubes a
> > real long and cool life, with a total current draw  of 120 mA!  The
> > filaments are series-parallel connected (all 6.3 V tubes) for 12.6 V
> > at 6 A.
> >
> > I own a pristine R-250M model. Its performance is simply incredible,
> > considering an early 50's design with all octal tubes (19 of them). It
> > outperforms many receivers 10 years more advanced. The spec on the
> > sensitivity is 0.6 uV  for S/N ratio of 10 dB at 3 KHz IF and 2.5 KHz
> > AF
> > bandwidth, with a 100 ohm antenna. Audio output is 0.5 W into 600 ohms
> > at 4%
> > (AF output tube is a Russian 6P6, which is the exact equivalent of the
> > 6V6).
> > Frequency stability is specified as maximum 200 Hz drift after a
> > warm-up of
> > 2 hours!
> > The tube complement in US equivalent designations is  10 x 6SK7, 3 x
> > 6AC7,
> > 3 x 6SA7, 2 x 6H6, 1 x 6V6, + a voltage regulator tube (I have to find
> > the
> > US equivalent) and the power supply has a 5Z4 rectifier.
> > The detector/BFO injection is good enough for good SSB reception, even
> > with
> > the AGC on, as well as CW is just great to copy on it with all the
> > selectivity options.
> > It's no slouch in AM quality, although  .5 W  is really not enough to
> > drive
> > a big speaker without an outboard amp.
> >
> > All this in a real "boatanchor" package of 26" wide, 18" deep and 21"
> > tall
> > (with the shock mounts), weighing 209 pounds, without the power supply,
> > which weighs about 35 pounds.
> > Options available were RTTY demodulator, high precision AFC (Automatic
> > Frequency Control) system, which provides tuning with a servo motor
> > and a
> > diversity control interface. There was also a vibrator power supply
> > option,
> > for 12 VDC input.
> >
> > Construction is really excellent quality and it looks like good US
> > mil-spec
> > work. The wiring and soldering are also first-class, the components
> > look
> > high quality. The transformers are potted, cased and painted, just
> > like the
> > US mil. stuff. Incidentally, I got a couple of sets of NOS spare
> > tubes, with
> > 1972 manufacturing date. Pretty late for still making metal octal
> > military
> > tubes!
> >
> > There are photos of the various versions at a Russian web site
> > http://www.cqham.ru/trx/r_250.html .
> >
> > Well, I hope this wasn't boring, but there is not too much traffic here
> > tonight anyway...
> >
> > 73, Meir WF2U
> > Gowensville, SC
> >
> >
> >  -----Original Message-----
> > From: r-390-bounces at mailman.qth.net
> > [mailto:r-390-bounces at mailman.qth.net]
> > On Behalf Of Bob Camp
> > Sent: Saturday, August 07, 2004 5:15 PM
> > To: Cecil Acuff; R-390 HF Receiver List
> > Subject: [R-390] Russian HF Radios
> >
> > Hi
> >
> > Well obviously we need to get something going.
> >
> > How about did the Russians build a better all tube HF receiver than the
> > R-390A? From what I hear the answer may be yes ....
> >
> > That's the way to see if anybody's listening.
> >
> > Enjoy!
> >
> > Bob Camp
> > KB8TQ
> >
> >
> > On Aug 7, 2004, at 4:57 PM, Cecil Acuff wrote:
> >
> >> Test...
> >>
> >> ______________________________________________________________
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> >
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>
>
>
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> End of R-390 Digest, Vol 4, Issue 6
> ***********************************