Apparently a LOT of ham transmitters were leaking today. I heard QSOs on 10, 14, 18, 21, and 28 MHz (California QSO Party). Really nice to hear things on those bands for a change.
Barry - N4BUQ > Hi > > Signal generators leak as well. One of the pretty normal “drill’s” on a VHF > generator was to grab a portable radio and see what you could detect as you > waved it around the generator. > > It was always a bit amazing to find two apparently identical generators that > had > very different leakage performance. Needless to say, the bad one headed back > to > the repair folks. Sometimes they could find the problem … sometimes they > couldn’t. Home made “EMI probes” typically got used a lot in that process. > > Bob > >> On Oct 6, 2024, at 2:22 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
