[R-390] Official specs

Sun Oct 6 14:34:22 EDT 2024

Hi Les,

For a minute there, I thought that link was to a cached copy of Nolan's
website.  It made me quite nostalgic but I then found that wasn't the
case.  I miss him...

Thanks,
Barry - N4BUQ

On Sun, Oct 6, 2024 at 1:22 PM Les Locklear <leslocklear at hotmail.com> wrote:

> Well, the type of coaxial cable used makes quite a difference too.
>
> Many years the R-390A "Guru" and e-mail favorite Nolan Lee stopped by my
> place for a visit. We discussed problems he was experiencing with "leakage"
> of signals on his coaxial cables he was using in his signal generators. I
> suggested he might want to try RG-223 vs. the RG-58 he was using. I had a
> good bit on hand and rolled out about 30 ft. for him to try along with a
> roll-around rack and antenna material in exchange for a couple of pieces of
> test equipment.
>
> Shortly after, he had a stroke or health event and wasn't to be heard from
> again. So, I don't know if he found success with the RG-223. But the
> results from this website should tell the tale:
> https://www.awcwire.com/allied-university/this-vs-that/rg223-vs-rg58?srsltid=AfmBOopRQ3OqIMcBjxiwimtP8KuLE3GiI_HOTGjmFRK1HZVtIg8KTyed
>
> If you are trying to get to "never,never" land on sensitivity
> specifications you might want to check how much leakage you have from the
> standard coaxial cables you might be using. "actual" measurements of 135 to
> 140 db are much more realistic for a well aligned/tuned R390A/URR. I would
> suspect the same from the older R-390/URR.
>
> I'm too old and slow to be doing "detective" work for any of you regarding
> being able to hear a "flea fart in Tahiti" on a particular receiver, but
> searching the internet and reliable websites will prove me right regarding
> coaxial cable used on "Test Equipment" or Signal Generators.
>
> Les Locklear
>
> Everyone has a photographic memory.
> Some people just don't have film.
> ..Unknown..
>
>
>
> ----- Original Message -----
> From: Bob  Camp <kb8tq at n1k.org>
> To: Ing. Giovanni Becattini <giovanni.becattini at icloud.com>
> Cc: <r-390 at mailman.qth.net>
> Sent: 10/6/2024 7:37:04 AM
> Subject: Re: [R-390] Official specs
>
> ________________________________________________________________________________
>
> > Hi
> >
> > There’s nothing wrong with the 80,82,84 generators considering when they
> came
> > out. They still can be useful. However keeping them in “full spec”
> running
> > condition  gets harder and harder as the years go by.
> >
> > Bob
> >
> >> On Oct 5, 2024, at 5:56 PM, Ing. Giovanni Becattini
> >> <giovanni.becattini at icloud.com> wrote:
> >>
> >> Hi Bob,
> >>
> >> Thanks for the interesting links. By means of them, I could discover
> that the
> >> model 80 is the civil version of my TS-497 which I bought almost for
> free
> >> because nobody wants it. It has wonderful mechanics and a very good
> attenuator
> >> which arrives down to 0.1uV.
> >>
> >>> Il giorno 5 ott 2024, alle ore 17:00, Bob Camp <kb8tq at n1k.org> ha
> scritto:
> >>>
> >>> Hi
> >>>
> >>> I’m quite sure the engineers involved understood this and that. The
> gotcha
> >>> is that these spec’s are written by a committee. Having sat for
> un-ending
> >>> amounts of time on some of those committee’s, what gets said is not
> always what
> >>> goes in the spec. This or that gets shoved off to some other process
> or
> >>> document ( or maybe simply ignored). Often the “shoved off” stuff
> turns into
> >>> informal notes that somebody using the spec very much needs to have
> handy.
> >>> Welcome to why you spend all those hours sitting there …. :) :)
> >>>
> >>> While that app note is a fun read, it turns out that it’s not the full
> >>> story. These generators do not always have a 50 ohm output impedance.
> Put a VNA
> >>> on one and crank the attenuator …. not always 50 ohms.
> >>>
> >>> If you take a look at this manual from 1945 (for the 80, a cousin of
> the 82):
> >>>
> >>>
> >>>
> http://bee.mif.pg.gda.pl/ciasteczkowypotwor/Boonton/Boonton_Model_80_Manual.pdf
> >>>
> >>> It includes an “optional 6 db pad”. Why? The output impedance was a
> bit
> >>> wonky (even for that era) without it.
> >>>
> >>> The model 82 (and its cousins the 80 and 84) came out in the while
> WWII was
> >>> still going on. They stayed in production for quite a while after that:
> >>>
> >>> https://www.worldradiohistory.com/Archive-Catalogs/Miscellaneous-
> >>> Manufacturers/Laboratory-Standards-1949-Catalog.pdf
> >>>
> >>> It’s a generator that “covers the frequency range”. (it’s the only one
> in
> >>> that catalog that does so). An equivalent would be another generator
> that
> >>> covers the frequency range.
> >>>
> >>> By the 1960’s most outfits had moved on from WWII test gear (if the
> spec
> >>> allowed them to do so).
> >>>
> >>> So:
> >>>
> >>> *Is* this a reason the sensitivity specs are a bit crazy? We simply
> don’t
> >>> know. We *do* know that they are more than a bit off from what every
> example of
> >>> the radio any of us have seen actually does. Given how tight the rest
> of the
> >>> specs’s are, That’s pretty strange.
> >>>
> >>> *Could* it be the reason? …. it just might be. You certainly can
> confusion
> >>> about that 6 db pad on the model 80 popping up in a lot of places.
> >>>
> >>> Bob
> >>>
> >>>> On Oct 4, 2024, at 11:13 PM, Jim Whartenby via R-390 <r-
> >>>> 390 at mailman.qth.net> wrote:
> >>>>
> >>>> BobI
> >>>> don't know why you are speculating "Since you can use any signal
> generator" when MIL-R-13947B(SigC) on page 20 specifies the Measurements
> Corp Model 82 signal Generator, or it's
> >>>> equal.  Your concern with matched impedances between the generator
> and the R-
> >>>> 390 may appear to be valid but this seems to have been accounted for
> in the R-
> >>>> 390 spec with higher input voltages to account for the mismatch
> losses.
> >>>> Collins and the Signal Corps specified the 125 ohm input impedance of
> the R-390
> >>>> and they were surely aware that the standard impedance of high end
> signal
> >>>> generators was normally 50 ohms.
> >>>>
> >>>> Check out http://hparchive.com/Boonton/BRC-The-Notebook-03.pdf which
> is a
> >>>> 1954 Boonton Radio explanation for the use of Dummy Antennas.
> Everything you
> >>>> need is in the first four pages.  It explains why the mismatch
> between 50 ohms
> >>>> and the receiver input impedance reduces the loading on the receiver
> input
> >>>> tuned circuits and recovers the Q of the receiver RF input tuned
> circuits.
> >>>> This also affects favorably the S+N/N measurement.  There is a reason
> for the
> >>>> apparent madness.
> >>>> Jim
> >>>>
> >>>> Logic: Method used to arrive at the wrong conclusion, with
> confidence.
> >>>> Murphy
> >>>>
> >>>>  On Friday, October 4, 2024 at 07:23:24 PM CDT, Bob Camp <
> kb8tq at n1k.org>
> >>>> wrote:
> >>>>
> >>>> Hi
> >>>>
> >>>> Based on a *lot* of interaction with DOD source inspectors over the
> years …
> >>>> it’s very much a “that depends” sort of thing. The guy you get this
> month may
> >>>> be *very* different than than the guy who comes in next month.
> >>>>
> >>>> Since you can use any signal generator, there is room for “trouble”
> with
> >>>> minimal specs. Typically the way this works out is a request to
> clarify things.
> >>>> Unfortunately that stuff does not get into the official specs. Yes,
> some of us
> >>>> have pointed that out as a problem …. never got addressed AFIK.
> >>>>
> >>>> Bob
> >>>>
> >>>>
> >>>>> On Oct 4, 2024, at 5:19 PM, Jim Whartenby via R-390 <r-
> >>>>> 390 at mailman.qth.net> wrote:
> >>>>>
> >>>>> Bob
> >>>>> You are over thinking the testing.  The generator is terminated but
> not in
> >>>>> it's characteristic impedance.  Collins and the agency letting the
> contract agreed on a test method and wrote it down in the test procedure.
> Anything that would affect the testing like VSWR has already been
> considered and accounted for.  That Hams don't
> >>>>> use the proper termination for the signal generator, according to
> the spec,
> >>>>> which affects the perceived sensitivity is another issue.  Spec is
> spec as they
> >>>>> say.
> >>>>>
> >>>>> Not all Government Source Inspectors are knowable about the
> equipment that
> >>>>> they are reviewing and putting their inspection stamp on.  Not all
> Signal Corps
> >>>>> equipment is inspected by Army GSIs.  Every once in a while, Army
> equipment
> >>>>> will have an anchor stamp on it and vice-versa.  Sometimes certain
> specs are
> >>>>> wavered if not considered critical, most often they are not.  Again,
> spec is
> >>>>> spec.
> >>>>> Regards,
> >>>>> Jim
> >>>>>
> >>>>> Logic: Method used to arrive at the wrong conclusion, with
> confidence.
> >>>>> Murphy
> >>>>>
> >>>>>   On Friday, October 4, 2024 at 02:43:36 PM CDT, Bob Camp <
> kb8tq at n1k.org>
> >>>>> wrote:
> >>>>>
> >>>>> Hi
> >>>>>
> >>>>> Ok …. but …..
> >>>>>
> >>>>> If it is simply a resistor, then the generator is unterminated. It’s
> >>>>> designed and calibrated to run into a 50 ohm load. If all that’s
> there is a
> >>>>> series resistor the generator is not properly set up (and thus not
> calibrated
> >>>>> ….). Yes some generators deal with this better than others.
> >>>>>
> >>>>> My guess is that there’s more to the load circuit than just that
> resistor.
> >>>>> Without a schematic …. who knows ….
> >>>>>
> >>>>> Bob
> >>>>>
> >>>>>
> >>>>>> On Oct 4, 2024, at 12:53 PM, Jim Whartenby via R-390 <r-
> >>>>>> 390 at mailman.qth.net> wrote:
> >>>>>>
> >>>>>> Bob
> >>>>>> But we do know what the interface is between the signal generator
> and
> >>>>>> antenna input.  On document page 20, the balanced RF input is in
> series with a
> >>>>>> 125 ohm non-inductive resistor and the unbalanced RF input is in
> series with a
> >>>>>> 50 pF capacitor.  Both interfaces do not include the generator's
> output impedance.
> >>>>>>
> >>>>>> As for the sensitivity not being what the R-390/URR or the
> R-390A/URR is
> >>>>>> capable of, well there are perhaps
> >>>>>> 100's of tests that the receiver must successfully pass before it
> is accepted.  Tightening any of the specs to exactly what the receiver may
> be capable of passing will guarantee that no one receiver will ever pass
> all of the acceptance tests.  Then there is the added problem of your test
> equipment's
> >>>>>> error tolerance and being traceable back to the NIST standards.  Is
> your 10
> >>>>>> microvolts from the signal generator really 10 microvolts?
> >>>>>>
> >>>>>> Unless otherwise stated, the specification calls out a value that
> the
> >>>>>> receiver must do better than.  A sensitivity of just under 6.5
> microvolts for a
> >>>>>> 10 dB S+N/N with an audio power output of 10 milliwatts seems
> reasonable over
> >>>>>> the range of 2 to 32 MHz for either balanced or unbalanced RF
> inputs.  This is
> >>>>>> perhaps typical for just about all HF receivers built for the
> military, at
> >>>>>> least for what I am aware of, but I am sure that there will be the
> rare
> >>>>>> exception.
> >>>>>>
> >>>>>> Regards,
> >>>>>> Jim
> >>>>>> Logic: Method used to arrive at the wrong conclusion, with
> confidence.
> >>>>>> Murphy
> >>>>>>
> >>>>>>   On Friday, October 4, 2024 at 09:39:26 AM CDT, Bob Camp <
> kb8tq at n1k.org>
> >>>>>> wrote:
> >>>>>>
> >>>>>> Hi
> >>>>>>
> >>>>>> The gotcah here is that we really don’t know what the interface
> between
> >>>>>> the signal generator and radio looked like for these official
> tests. Despite
> >>>>>> the document going into a lot of detail, they did not include a
> schematic or a
> >>>>>> part number. (or at least not one that I could find). There are a
> *lot* of ways
> >>>>>> they might have been doing things …..
> >>>>>>
> >>>>>> Bob
> >>>>>>
> >>>>>>> On Oct 4, 2024, at 10:19 AM, Ing. Giovanni Becattini via R-390 <r-
> >>>>>>> 390 at mailman.qth.net> wrote:
> >>>>>>>
> >>>>>>> But when we perform the classical sensitivity test with a
> modulated
> >>>>>>> signal, do we get the AM or CW value?
> >>>>>>>
> >>>>>>> Following the instructions I got a value of -104 dBm, i.e. 1.41
> uV.
> >>>>>>> Because I used the DA-121, the real value should be even better,
> far from 5 uV.
> >>>>>>> And surely my R-390A is not as good as it could be .
> >>>>>>>
> >>>>>>> Is my reasoning correct?
> >>>>>>>
> >>>>>>>> Il giorno 4 ott 2024, alle ore 16:13, Barry <n4buq at knology.net>
> ha
> >>>>>>>> scritto:
> >>>>>>>>
> >>>>>>>> I don’t think of 1uV as “bad” but most of these radios will beat
> that.
> >>>>>>>>
> >>>>>>>> Thanks,
> >>>>>>>> Barry
> >>>>>>>>
> >>>>>>>>> On Oct 4, 2024, at 8:55 AM, Ing. Giovanni Becattini via R-390 <r-
> >>>>>>>>> 390 at mailman.qth.net> wrote:
> >>>>>>>>>
> >>>>>>>>> ?Wow, thanks!
> >>>>>>>>>
> >>>>>>>>> By the way, do you know why the sensitivity values were so bad?
> Are we
> >>>>>>>>> the ones who are taking measures that are too lenient or are
> they the ones who
> >>>>>>>>> were too conservative?
> >>>>>>>>>
> >>>>>>>>> Thanks again
> >>>>>>>>>
> >>>>>>>>> Gianni
> >>>>>>>>>
> >>>>>>>>>> Il giorno 4 ott 2024, alle ore 15:37, Larry Haney
> >>>>>>>>>> <larry41gm2 at gmail.com> ha scritto:
> >>>>>>>>>>
> >>>>>>>>>> Hi Gianni and Barry,  Tom Marcotte and Al Tirevold (SK)
> obtained and
> >>>>>>>>>> cleaned up the specs for the 390A and put it on our website.
> Here's the link: mil-r-13947b– (r-390a.net) <
> https://www.r-390a.net/mil-r-13947b.pdf>. Unfortunately, the entry in
> References page indicates it is for the R390(), but it is also the the
> 390A.  I will be changing that shortly.
> >>>>>>>>>>
> >>>>>>>>>> Regards, Larry
> >>>>>>>>>>
> >>>>>>>>>>> On Fri, Oct 4, 2024 at 4:49 AM Ing. Giovanni Becattini via
> R-390 <r-
> >>>>>>>>>>> 390 at mailman.qth.net <mailto:r-390 at mailman.qth.net>> wrote:
> >>>>>>>>>>> Have ever been released official specs for the 390A?
> >>>>>>>>>>>
> >>>>>>>>>>> The manuals report few data and neither too correct, for what
> I can
> >>>>>>>>>>> understand (e.g., sensitivity)
> >>>>>>>>>>>
> >>>>>>>>>>> Thanks
> >>>>>>>>>>> ______________________________________________________________
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> >>>>>>>>>>>
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