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 <leslockl...@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 <kb...@n1k.org> > To: Ing. Giovanni Becattini <giovanni.becatt...@icloud.com> > Cc: <r-390@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.becatt...@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 <kb...@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- > >>>> 3...@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 < > kb...@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- > >>>>> 3...@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 < > kb...@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- > >>>>>> 3...@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 < > kb...@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- > >>>>>>> 3...@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 <n4...@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- > >>>>>>>>> 3...@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 > >>>>>>>>>> <larry41...@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- > >>>>>>>>>>> 3...@mailman.qth.net <mailto:r-390@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 > >>>>>>>>>>> ______________________________________________________________ > >>>>>>>>>>> R-390 mailing list > >>>>>>>>>>> Home: http://mailman.qth.net/mailman/listinfo/r-390 > >>>>>>>>>>> Help: http://mailman.qth.net/mmfaq.htm > >>>>>>>>>>> Post: mailto:R-390@mailman.qth.net <mailto: > R-390@mailman.qth.net> > >>>>>>>>>>> > >>>>>>>>>>> This list hosted by: http://www.qsl.net <http://www.qsl.net/> > >>>>>>>>>>> Please help support this email list: > http://www.qsl.net/donate.html > >>>>>>>>> > >>>>>>>>> ______________________________________________________________ > >>>>>>>>> R-390 mailing list > >>>>>>>>> Home: http://mailman.qth.net/mailman/listinfo/r-390 > >>>>>>>>> Help: http://mailman.qth.net/mmfaq.htm > >>>>>>>>> Post: mailto:R-390@mailman.qth.net > >>>>>>>>> > >>>>>>>>> This list hosted by: http://www.qsl.net > >>>>>>>>> Please help support this email list: > http://www.qsl.net/donate.html > >>>>>>>> > >>>>>>> > >>>>>>> ______________________________________________________________ > >>>>>>> R-390 mailing list > >>>>>>> Home: http://mailman.qth.net/mailman/listinfo/r-390 > >>>>>>> Help: http://mailman.qth.net/mmfaq.htm > >>>>>>> Post: mailto:R-390@mailman.qth.net > >>>>>>> > >>>>>>> This list hosted by: http://www.qsl.net > >>>>>>> Please help support this email list: > http://www.qsl.net/donate.html > >>>>>> > >>>>>> ______________________________________________________________ > >>>>>> R-390 mailing list > >>>>>> Home: http://mailman.qth.net/mailman/listinfo/r-390 > >>>>>> Help: http://mailman.qth.net/mmfaq.htm > >>>>>> Post: mailto:R-390@mailman.qth.net > >>>>>> > >>>>>> This list hosted by: http://www.qsl.net > >>>>>> Please help support this email list: http://www.qsl.net/donate.html > > >>>>>> ______________________________________________________________ > >>>>>> R-390 mailing list > >>>>>> Home: http://mailman.qth.net/mailman/listinfo/r-390 > >>>>>> Help: http://mailman.qth.net/mmfaq.htm > >>>>>> Post: mailto:R-390@mailman.qth.net > >>>>>> > >>>>>> This list hosted by: http://www.qsl.net > >>>>>> Please help support this email list: http://www.qsl.net/donate.html > >>>>> > >>>>> > >>>>> ______________________________________________________________ > >>>>> R-390 mailing list > >>>>> Home: http://mailman.qth.net/mailman/listinfo/r-390 > >>>>> Help: http://mailman.qth.net/mmfaq.htm > >>>>> Post: mailto:R-390@mailman.qth.net > >>>>> > >>>>> This list hosted by: http://www.qsl.net > >>>>> Please help support this email list: http://www.qsl.net/donate.html > >>>> > >>>> > >>>> ______________________________________________________________ > >>>> R-390 mailing list > >>>> Home: http://mailman.qth.net/mailman/listinfo/r-390 > >>>> Help: http://mailman.qth.net/mmfaq.htm > >>>> Post: mailto:R-390@mailman.qth.net > >>>> > >>>> This list hosted by: http://www.qsl.net > >>>> Please help support this email list: http://www.qsl.net/donate.html > >>> > >>> ______________________________________________________________ > >>> R-390 mailing list > >>> Home: http://mailman.qth.net/mailman/listinfo/r-390 > >>> Help: http://mailman.qth.net/mmfaq.htm > >>> Post: mailto:R-390@mailman.qth.net > >>> > >>> This list hosted by: http://www.qsl.net > >>> Please help support this email list: http://www.qsl.net/donate.html > >> > > > > ______________________________________________________________ > > R-390 mailing list > > Home: http://mailman.qth.net/mailman/listinfo/r-390 > > Help: http://mailman.qth.net/mmfaq.htm > > Post: mailto:R-390@mailman.qth.net > > > > This list hosted by: http://www.qsl.net > > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ > R-390 mailing list > Home: http://mailman.qth.net/mailman/listinfo/r-390 > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:R-390@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ R-390 mailing list Home: http://mailman.qth.net/mailman/listinfo/r-390 Help: http://mailman.qth.net/mmfaq.htm Post: mailto:R-390@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
