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As I recall, the "60 Hz" vertical scan rate for NTSC is not supposed to be exactly 60 Hz, but slightly different, to provide color and still maintain integer counting values. Likewise, the horizontal is not 15,750 Hz as in monochrome, but something like 15,734. This was all part of the trick to squeeze the vector modulated color info into the spaces between the normal monochrome scan spectral lines, and magically work for both color and B&W TV sets, with "mostly" full compatibility, and without needing any extra channel bandwidth. If you study up on NTSC, you can get the exact values and rationale of the scheme. I've always found it quite fascinating how this was figured out and done way back when. I used to understand it, but it's been a lot of years. Anyway, you can force your unit to run at exactly 60 Hz by tweaking the oscillator to match whatever divide ratio is used. The HP/Grass Valley thing likely wasn't intended to make exactly 60 Hz, but the NTSC version of it. Changing that to real 60 Hz would be a much bigger project. Ed

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I have seen a little discussion of feed line ingress amplitude with coax vs twisted pair. My position was influenced by Dallas Lankford when he was building directional phased MW antenna systems. When he was having a hard time nulling an unwanted signal and tried a twisted pair speaker wire, it was a but of a eureka moment for him and he continued using twisted pair and also CAT5 cable. I would like to see definitive tests done on the question, Such as stretch out 150ft of coax and 150ft of CAT5 on the ground and do listening tests. Questions I have, I suspect you would want to terminate the far end in the cables in their characteristic impedance. For the CAT5, a 100Ω to 50Ω transformer should be used at the input of the testing receiver. What should be done to the other 3 pairs in the CAT5? How about parallel connecting two of the twisted pair in a CAT5 for a 50Ω characteristic impedance? How does that affect the signal ingress? MW is good for testing, because of large continuous signals to measure signal strength. I don't know how well that translates to HF. I know Common modes chokes can be added to both to reduce ingress. There are different qualities of both Coax a (solid braid) and CAT5/6 (UUTP, F/UTP, and F/FTP) So, I would expect a comparison of better quality cables. I'd like your thoughts on how this test would be performed, I suspect a Spectrum analyzer would be useful in the testing. Thanks, Mikek

I am looking for Philips PM3070 Operator Manual, I have the service manual I just cannot find the operator manual I am trying to find in the menu how to set the 2 chs as on mine the the 2chs are summed together and I cannot figure out how to clear that to make them independent. thanks for any helps

Ed Breya <edbreya@...> added the album Ed's Q meter project : building the box, heading toward final design The following photos have been uploaded to the Ed's Q meter project album of the [email protected] group. top.jpg 4 gang capacitor.jpg final shield wrap.jpg finished transformer.jpg front inner.jpg front outer.jpg mounting collet.jpg By: Ed Breya <edbreya@...>

Jeff, many thanks for posting this. I've known W1HIS for decades, though I haven't seen him in at least 10 years. I always knew him as Chuck, a professor at MIT, and never knew he was a ham! Fun fact - Chuck was the principal inventor of differential GPS, which enabled measurements with millimeter-level accuracy back in the early 1980s when the US government was still "fuzzing" GPS satellite transmissions. In 2008 the American Geophysical Union awarded him the Charles A. Whitten Medal for this invention.

The following files and folders have been uploaded to the Files area of the [email protected] group. /Jeff's Stuff/Noise sniffing and finding.zip By: Mike - K8CN <k8cn@...> Description: Folder provided by Chuck Counselman, W1HIS on his B-field loop for near field RF current sensing

I have a new to me Sola constant voltage transformer. I am curious as this is a VERY vintage model it has an output at 115 Vac. I am hoping to use this to soften the power line in for some of my tube testers so that i can take some of the stress off the line adjust pots in the testers as they are becoming unobtainable. However being new to this gear I am not sure what is "normal operation" and should I change the cap. It has an extremely large non polar 16uF cap at 660 Volts. This is a bathtub oil filled capacitor. Also the input characteristics are HORRINDUS under no load it is burning about 84 Watts of power. But it is happily supplying 118.5Vac to a dmm and nothing else. It also has an appauling power factor of about .224 Some Images can be found here: /g/Test-Equipment-Design-Construction/album?id=284406 Eric

Ed Breya <edbreya@...> added the album Ed's Q meter transformer: first round build

The following photos have been uploaded to the Ed's Q meter transformer album of the [email protected] group. T1 and T2 closeup.jpg 0 to 1 MHz.jpg 0 to 100 MHz.jpg 0 to 200 MHz.jpg 0 to 250 MHz.jpg 10 dB lower with output shorted.jpg at 1 dB per div.jpg mesh repair.jpg normal level 0 to 100 MHz.jpg overall view.jpg shorting output with mesh.jpg By: Ed Breya <edbreya@...>

Hello, Here is the link to the current probe that I built to be used from 50 KHz to 50 MHz: http://ve2azx.net/technical/RF_CurrentProbe_1VperAmp.pdf I also have an external Current Probe for the MFJ 854 that covers 100 KHz to 50 MHz using an Irwin Clamp: http://ve2azx.net/technical/MFJ%20854_curr_Xfrm.pdf Jacques Audet VE2AZX ve2azx.net

The following photos have been uploaded to the Ed's Q meter transformer album of the [email protected] group. test setup.jpg parts.jpg By: Ed Breya <edbreya@...>

Good stuff. I have turned on a dozen techs to this. Now if could find USAF training manuals. I stupidly left them in a closet when moving. About 7 foot wide stack. Get Outlook for Android<https://aka.ms/AAb9ysg>

Before I retired federal civil service (Naval Station Norfolk) 2 years ago, I found out that there were none of the NEETS series issued in print anymore, and I also attempted to go to Langley AFB to see if the base ESO had any copies of AFSC PMEL courses that I took many years ago. They don't print them anymore and would not say if they were taught anymore. Even if they had given me access or digital copies I would have printed them out. All have great information in them. If you run into any of them, there is a lot of stuff to learn. 73 Richard W4MCD

The following photos have been uploaded to the Ed's Q meter transformer album of the [email protected] group. parts 2.jpg complete unit 1.jpg complete unit 2.jpg parts 1.jpg By: Ed Breya <edbreya@...>

wrote: Interesting. What's the spectrum ? Is it the switching converter or the rectification ? Big Clive recently did a teardown of an LED bulb with no switcher : https://www.youtube.com/watch?v=WhcOlbLlNCg

wrote: Thank you. The assumption is "AC mains exhibit an impedance of 50 ohms." This is a It would be very specific to individual circumstances though. I used two BN 73-202 binocular cores with a 6:6 turns. > There’s some writing on the left hand side. I originally thought it was 215 cm + 501 dm. Then it looks a bit like an integral. ?? Thank you for sharing this. > Dave Dr. David Kirkby, Kirkby Microwave Ltd, drkirkby@... https://www.kirkbymicrowave.co.uk/ Telephone 01621-680100./ +44 1621 680100 Registered in England & Wales, company number 08914892. Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United Kingdom

Hi everyone, im in the process of designing and building an automatic antenna tuner using some large variable caps. These are attached to Stepper motors for which i have no info. The motors are Philips 400mN/M 1.8 deg. Marked with the following numbers which i assume are part numbers :- 9904 115 23101 MB21 4386 Ive tried searching for data on these motors without success, and i understand Philips no longer make stepper motors. Has anyone got any datasheets or an old data book with the info please Kind regards Pete

Hi folks, does anyone have experience of a Fabry-Perot Open Resonator for dielectric solid and fluid characterisation at microwave/mmwave? I want to build one (!) but not simply copy how it's been done before. Ideas about aperture feed arrangements, spherical mirror dimensions and focal length and the pros/cons of the lower mirror being planar would he helpful. Sort of an etalon for radio type of thing. Application is measuring the permittivity and loss tangent of dielectric sheets and thin layers of dielectric fluids at 20 to 120 GHz. Initial use case is measuring the performance of 3D printed dielectrics (Filament filled with TiO2 or UV resin filled with ceramic particles). I'm also making some split-post dielectric resonators for low frequencies sub-20 GHz, but if I can find suitable dielectric resonator pucks for 24GHz it would be useful to have both types to cross-calibrate them. Another project in my pipeline is a set of waveguide cavity perturbation fixtures for characterising thin dielectric rods. Someone buy me a PNA-X please. Neil https://youtube.com/MachiningandMicrowaves