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OT, but fairly basic question- rf detectors
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Ok, so I have Telonic SM-2000 sweeper from about '64, which appears to be working correctly, but in order to ~calibrate it (or even completely verify operation) and need an appropriate rf detector.? The user manual is no help, "see our literature for recommended detectors", ...right...? The only plugin modual I have spans 0-20Mhz, so we're not talking high speeds here.? There's got to be a simple schottky based circuit that would work here.?
Any ideas?? Thanks!? -Dave [Non-text portions of this message have been removed] |
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Dave:
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I'm assuming that you don't have access to a spectrum anlyser..... How about just plugging up to an oscilliscope with a 50 ohm thro-termination (or equivalent) ?? 0dBm = 0.632v p-p John --- In hp_agilent_equipment@..., d.seiter@... wrote:
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Be careful! your "RF detector must have a wide enough bandwidth to "see"
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the signal at full amplitude. Perhaps you can borrow a good HP Power Meter to do the job. As a last ditch' approach, a capacitance coupled full wave detector using a pair of good diodes in series, the mid point cap coupled to the RF signal to be detected, first diode other end connected to ground, the remaining diode end connected to a resistor and bypass cap will develop very close to peak -to-peak voltage. That you can easily convert to RMS. Ed Lawrence WA5SWD -- You and I are each unique, just like everyone else! -------------- Original message ----------------------
From: "John S" <John@...>
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Hi John,
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Actually, I have 4 analysers...? The issue is that this sweeper is designed so that signal goes out to the DUT, through the detector and back into the sweeper before returning out again as H and V signals for a scope or plotter.? The detector expected is a simple BNC in/out type. -Dave ----- Original Message -----
From: "John S" <John@...> To: "hp agilent equipment" <hp_agilent_equipment@...> Sent: Monday, September 21, 2009 2:30:40 PM GMT -08:00 US/Canada Pacific Subject: [hp_agilent_equipment] Re: OT, but fairly basic question- rf detectors ? Dave: I'm assuming that you don't have access to a spectrum anlyser..... How about just plugging up to an oscilliscope with a 50 ohm thro-termination (or equivalent) ?? 0dBm = 0.632v p-p John --- In hp_agilent_equipment@... , d.seiter@... wrote:
[Non-text portions of this message have been removed] |
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Hi Dave I have a 2000 under the bench somewhere it has a problem I havent
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sorted yet, I was hooked on those "compactrons" :-)) It is probably propping up the bench !! I think any "diode probe" circuit would do, even using a silicon 1N4148 or 1N914. these were not precision equipments and were used only at faily high levels. The return to the mainframe is generally for the mixing in of markers, and is not essential if you dont want the markers. I have collected a number of Marconi, GR and, and HP diode detectors most would be overkill as they are rated to 10GHz or higher. Alan G3NYK ----- Original Message -----
From: <d.seiter@...> To: "hp agilent equipment" <hp_agilent_equipment@...> Sent: Monday, September 21, 2009 11:45 PM Subject: Re: [hp_agilent_equipment] Re: OT, but fairly basic question- rf detectors Hi John, Actually, I have 4 analysers... The issue is that this sweeper is designed so that signal goes out to the DUT, through the detector and back into the sweeper before returning out again as H and V signals for a scope or plotter. The detector expected is a simple BNC in/out type. -Dave ----- Original Message ----- From: "John S" <John@...> To: "hp agilent equipment" <hp_agilent_equipment@...> Sent: Monday, September 21, 2009 2:30:40 PM GMT -08:00 US/Canada Pacific Subject: [hp_agilent_equipment] Re: OT, but fairly basic question- rf detectors Dave: I'm assuming that you don't have access to a spectrum anlyser..... How about just plugging up to an oscilliscope with a 50 ohm thro-termination (or equivalent) ?? 0dBm = 0.632v p-p John --- In hp_agilent_equipment@... , d.seiter@... wrote: working correctly, but in order to ~calibrate it (or even completely verify operation) and need an appropriate rf detector.? The user manual is no help, "see our literature for recommended detectors", ...right...? The only plugin modual I have spans 0-20Mhz, so we're not talking high speeds here.? There's got to be a simple schottky based circuit that would work here.?
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Here is some info about those things. Very easy to make when it's under 1GHz. I made several using geramnium, schottkey and kristaldiodes. For small signals with lowlevel the shunt type is the best option I think.
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Fred --- In hp_agilent_equipment@..., "Alan Melia" <Alan.Melia@...> wrote:
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John Griessen
Alan Melia wrote:
I have collected a number of Marconi, GR and, and HP diode detectors most would be overkillfredschneider2001 wrote: Here is some info about those things. Very easy to make when it's under 1GHz. Alan or anyone, How do you identify which of the old detector diodes go up to 2.4GHz? That's the frequency where I want to do some relative measurements to select good antenna layouts for peak power transfer with milliwatt chip radios. I'll be teeing off of a folded dipole antenna fed to a dummy load of 200 Ohms, (the antenna impedance), to go to the detector. One old diode I have is a gold plated cylindrical can with ceramic middle and a gold pin on the other end marked 1N21B and "microwave" and uA surrounded by a square. The diode has an adjusting screw on the flange end of the cylinder can! Does that mean cat whisker connection? That one is part of a X485B detector mount that attaches to 1cm X 3cm waveguide. I have some other diodes like it from slotted lines. How do you tell how fast they are? John Griessen |
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Joe Na
John,
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?? The 1n21B is an OLD diode! That style is what we used to call a 'Microwave' diode back when I was a kid in the early 1960s and it was OLD even then. In fact those are the first self-contained diodes ever built. They were developed during WW II and they talk about them in the MIT Radiation lab books that describe electronics developments made during the war. It's a silicon diode and you're right it does use a cat whisker! The screw moves the whisker around on the crystal for the best contact and they're then potted with wax so don't move the screw unless you have to and unless you know what you're doing. I have no idea how high the 1N21s go in frequency or how good they are relative to newer diodes but I strongly suspect that the newer diodes are much better! --- On Tue, 9/22/09, John Griessen <john@...> wrote:
From: John Griessen <john@...> Subject: Re: [hp_agilent_equipment] Re: OT, but fairly basic question- rf detectors To: hp_agilent_equipment@... Date: Tuesday, September 22, 2009, 5:22 PM ? Alan Melia wrote: I have collected a number of Marconi, GR and, and HP diode detectors most would be overkill as they are rated to 10GHz or higher. fredschneider2001 wrote: > Here is some info about those things. Very easy to make when it's under 1GHz. > . mcmaster. ca/~elmer101/ sqlaw/sqlaw. html Alan or anyone, How do you identify which of the old detector diodes go up to 2.4GHz? That's the frequency where I want to do some relative measurements to select good antenna layouts for peak power transfer with milliwatt chip radios. I'll be teeing off of a folded dipole antenna fed to a dummy load of 200 Ohms, (the antenna impedance), to go to the detector. One old diode I have is a gold plated cylindrical can with ceramic middle and a gold pin on the other end marked 1N21B and "microwave" and uA surrounded by a square. The diode has an adjusting screw on the flange end of the cylinder can! Does that mean cat whisker connection? That one is part of a X485B detector mount that attaches to 1cm X 3cm waveguide. I have some other diodes like it from slotted lines. How do you tell how fast they are? John Griessen |
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J. Forster
One old diode I have is a gold plated cylindrical can with ceramic middleuA stands for Microwave Associates. That style of diode was used in WW II gear and up until the 1970s at least for S and X band mixers. Ther also came in an R version (reverse polarity) They are point contact, but I'd leave the screw alone. The diode has an adjusting screw on the flange end of the cylinder can!That's an HP X Band (10 GHz) WG detector, if I remember correctly. I have some other diodes like it from slotted lines. How do you tell howA slotted line is at least a 1/2 wavelenght long, so that'll give you some idea. What are you trying to do with the diode? If you are looking for something to level a sweeper or something, I'd look for something commercially made. A wire is not just a wire above a hundred MHz or so. FWIW, -John ============== |
and a gold pin on the other end marked 1N21B I have some other diodes like it from slotted lines. How do1N25 series ~ 1-2GHz (L-band) 1N21 series ~ 2-4GHz (S-band) 1N23 series ~ 8-12GHz (X-band) 1N78 series ~ 12-18GHz (Ku-band) 1N26 series ~ 18-26.5GHz (K-band) 1N53 series ~ 26.5-40GHz (Ka-band) They of course work at lower frequencies, but the construction optimises the noise figure in the microwave frequency range above. I've most commonly come across these as part of General Radio slotted line and impedance meter products, usually 1N21 and 1N23 in mixer and rectifier applications. Craig |
John Sykes
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