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At odd moments over the last couple years I've been working on a cheap, easy to build design for a signature analyzer to be more or less comparable to the HP 5004a or Tek 308. I plan on making the design freely available. It annoys me to no end that these instruments have gotten as expensive as they have and this is my response to it. It follows the same general design as the Tek 308 with some TTL logic to implement the CRC register and a microprocessor for the UI. In this case I'm using an AT Mega 2560 Pro driving a 4x20 LCD display. These are easily available, cheap (tenish for the processor, sixish for the display) and the tool chain is widely available and free. That processor is actually a bit overkill, a nano has enough i/o but lacks sufficent ram, so I'm stuck with that without going to a bare chip. I finally got back to it the other week (in order to avoid doing other work :-) and yesterday actually got it to produce it's first actual signatures that match up with my HP5004a. If you want to see a picture of the display, I posted it over in the eevblog test equipment forum under the title "signature analyzer project". Anyone have any interest in updates? -- Paul Amaranth, GCIH | Manchester MI, USA Aurora Group of Michigan, LLC | Security, Systems & Software paul@... | Unix/Linux - We don't do windows

Back in the late 1970’s I encountered the same tackiness in customer units. Is there any coloration difference or filming on the meter? Smoking in repair facilities was acceptable at that time and units we received from Greece and Turkey were particularly bad. We cleaned those units externally with a strong soap and water solution, then a 92% alcohol wash. All glass surfaces were then cleaned with the original Bonami glass cleaner (alcohol and a glass cleaner spray). If we needed to clean the inside of the instrument, we followed the previous procedure, after the alcohol wash we would blow dry the circuit boards with compressed air or oven dry the boards for an hour or longer. The alcohol wash would significantly reduce the tackiness if it was due to smoking residue. Don Bitters

I have done this a couple of times. First I wash with warm water and soap (sulfo) Then clear it with alcohol When completely dry, I covered it with talcum powder Then brushed it away with a soft brush and compressed air. (Gently) Hans Sendt fra Yahoo Mail p? Android P? tir., den 11. jul. 2023 klokken 11:02, PAUL NICKALLS via groups.io <paulnick@...> skrev: I have had some success on other items with a strong solution of sodium bicarbonate which is readily available for cooking purposes. I apply it with a rag allowing a little time for it to penetrate. There are usually some surfaces on HP lids that are out of sight and thus good for experimentation. I am not sure about baking powder which has some added acid. Paul G8AQA On 11/07/2023 09:07, Leon via groups.io wrote: Something similar happened to my old Nikon D80 camera. I cleaned it with Iso-Propyl Alcohol (IPA). It removed all the stickeyness. Leon Heller

First post & maybe this is OT and if so please delete it. I am looking for the calibration procedure for a: Amprobe 37XR-A DMM. When I check it on my calibration source, everything is good but the resistance measurements which read low. I did check the calibrator with my Fluke 189 & they are spot on. I already called Amprobe/Fluke & they were no help. Thanks. -- -Bob

I had never heard of the ICS511, so looked it up. It could be very useful, but I think it's geared for much higher frequencies (like crystal oscillator multiplying), not audio like you describe. You probably would be better off using all CMOS like 4000 series or 74HC, which both have the classic 4046 PLL that you mentioned. You can make an input amplifier with a self-biased CMOS inverter string like with 4049 or 74C(or HC)04 "UB" (un-buffered) style, to save power, and skip the JFETs. If the input signal will be big enough, a 74HC14 would be simpler yet. I never use TTL anymore, except for maintenance on old gear. If you go with a 4046 type, I think it has this input buffer function built in already (maybe not the old original 4000 series one, but I'm pretty sure the 4046A, 4046B, and 74HC4046(X) do), so all you'd need is a coupling capacitor and some protection from abuse. So, two CMOS ICs could mostly do it, say a 74HC4046 and a 74HC390. The HP counter you recalled is likely the 5345A reciprocal counter, based on time difference to frequency readout conversion - about 9-10 digits resolution at almost any frequency, with one second gate time. No waiting around to count millions of actual cycles, it just needs to make an accurate time period measurement (with 500 MHz internal clock, plus interpolation), then calculates frequency. The more cycles available, the more it can average to improve the answer. Ed

i have 20GB, about 8000 files, on components,and units that my company, and it's predecessor, accumulated over 40 years. In some cases there are sever copies of the same file based on release date. true a good bit is available on MANY other sites but we have it in one place. it's to much to copy to somewhere but i'd like to make it available to others on this and other sites. i have a web server with a fixed IP address can someone point me at methods to: 1. allow access to others 2. maintain a high level of security Please PM with ideas Steve

I've never used one for that purpose, but you will likely need to add an attenuator, as most noise bridges will overload front ends. Give it a try and report back. -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 420 Via Palou Mall Stanford University Stanford, CA 94305-4070 http://www-smirc.stanford.edu

Jeff, First, the type of antenna you need to use is dependent upon your frequency range of interest. And from that if you are looking for accurate field strength measurements you have to use an antenna with a known antenna factor (AF) or to put it basically, a known gain figure to know what signal level it is giving you. This is usually obtained by comparing your subject unknown antenna under test (AUT) against a known gain antenna on either an open test range or in an anechoic chamber. There can be more simpler approaches (somewhat including theoretical) determining the antenna factor but all depends upon what you are using for your test environment, reference antenna or other means to obtain a known field strength measurement at your AUT location. Any of these approaches with loose field strength data will give you loose results when trying to obtain the antenna factor. If you are planning on using a specific antenna for relative (comparison) measurements I wouldn’t be as worried about an accurate antenna factor. But if you are doing absolute signal level measurements then you need to have reasonable accuracy in order to determine the field strength you are measuring. Aside from this the gain of an antenna is not necessarily flat over its usable frequency range. Manufacturers of EMC (Electro Magnetic Compatibility) test range antennas will usually provide a curve indicating the AF over that range of frequencies. I have basically leaned on the side of very accurate antennas in this note. And from looking at some of the antennas in the links below you will find that they are manufactured to very high standards. This is primarily because these antennas are required to take measurements that are used to provide test results in accordance to very stringent government and industry standards (i.e. FCC, IEC, VDE, CSA, etc.) Below are few reference links regarding antenna calibration plus some examples of manufacturers and distributors who provide calibrated antennas for precision measurements that are sometimes very esoteric. Don’t be shocked by what you see in the way of antennas. These are utilized for highly accurate measurements but will give you an idea of the style that are used for various frequency ranges when employed in a precision test environment. https://ewh.ieee.org/r6/scv/emc/archive/2015/052015Kramer.pdf https://www.nsi-mi.com/images/Technical_Papers/Articles/NSI-MI-Antenna-Gain-Calibration-on-a-Ground-Reflection-Range.pdf https://www.electronicdesign.com/home/article/21201615/the-importance-of-antenna-calibration https://incompliancemag.com/article/antenna-parameters-and-antenna-calibration/ https://en.wikipedia.org/wiki/Gain_(antenna) https://aaroniausa.com/rf-spectrum-analyzer/calibrated-antennas-for-radio-frequency-analysis/ https://www.everythingrf.com/search/all-antennas/filters?page=1&country=global&sindustry=;EMC ; https://www.ets-lindgren.com/products/antennas?page=Products-Landing-Page I hope this helps. Greg

I am looking for the schematics of the A5 Receiver Assembly for an HP8711A. HP's relevant Component Level Repair Service Guide ( # 08711-9004) is giving the wrong information. There the schematics are given for the 50 Ohm version ( 08711-60105 ) instead of the required 75Ohm version (-08711-60070 ). 73, Frans PA0FVE

The reactive part of the impedance of resistors of this value is unpredictable at best. Of course for RF amplifiers the value would have to be scaled down quite a lot. Even so resistors still have self-inductance as well as shunt capacitance. A satisfactory measurement could be made over a narrow frequency range if the resistor could be characterized over the range. 73 (Regards). Max K 4 O D S. I've Never Lost the Wonder. Sent: Monday, May 15, 2023 8:30 PM To: [email protected] Subject: [Test Equipment Design & Construction] This PDF shows one way to perform a simplified measurement of an audio amplifier: This PDF shows one way to perform a simplified measurement of an audio amplifier: https://www.jensen-transformers.com/wp-content/uploads/2014/08/as048.pdf I realize this almost certainly will not work for RF...but it might...any ideas? Jensen is a major player in extremely high end audio transformers. Their application notes are very informative. i

You can also do it by measuring the capacitance, if you know the length. Ed

I saw this about Great Scott developing an RF testing platform. Appears to be in early development. https://greatscottgadgets.com/2023/05-04-development-of-a-universal-radio-test-instrument/ -- Dave, AA6RE

Hi Jeff, Can you clarify a bit more what part confuses you? Bruce designed this amplifier to buffer (and slightly amplify) low phase noise frequency references and the goals for it are low residual/additive phase noise, low distortion, and high reverse isolation. The high reverse isolation is needed to prevent oscillator injection locking when performing frequency stability measurements. The 40 dB or so of reverse isolation is much better than the original Norton amplifier but is still quite a bit less than other amplifiers with similar purposes. If you look at the isolation amplifiers NIST has designed for their atomic clocks the reverse isolation is north of 100 dB. It’s not too difficult to find an opamp with high reverse isolation, but it’s harder to find one that also has very low additive phase noise. Matt

Question is the in the subject line. I guess if I see my post, I'll know no one has any thing to discus lately! Mikek

Now the base functionality of my DIY counter/timer is working I'm puzzled about adding an external trigger input. Never used such an input. I known from user manuals it is supposed to trigger the opening (and closing??) of the counter gate, possibly after multiple pulses and a programmable delay. Anyone here that ever used such an input? For what purpose? What would be the main requirements for such an input?

Hi, I picked up an Metcal PS2E-01 power supply at a hamfest recently. It did not come with an iron. I tried the iron from my MX500P system and it heated up to soldering temperature and seemed OK. There is a 1993 dated test sticker on the supply, so it is not a recent model. Metcal has sold several different appearing power supplies, and I am wondering if the irons are compatible from model to model? Connector compatibility seems like kind of a risky metric for this kind of thing. Does anybody know if there are differences in output power or frequency between models? Thanks, BobH KE7FEF

Hi all, some help needed please. I have recently acquired a nice high power RF balun, ex Mod. Rediffusion 12054B. I have been told it was used on a HF set on a Royal Navy Frigate. It has 3 RF Connectors, the 2 inputs for 12.5R & 25R are PL259 types, the output at 50R is a large connector i know not which. It is not an N Connector but looks similar. The outside diameter is 18.9mm (0.7440"). Can anyone id this connector for me please