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Can't open the pdf on my galaxy

Try this :

73

Xtian

-------- Original message --------

From: Jeff Green <Jeff.L.Green1970@...>

Date: 3/21/23 7:47 PM (GMT-08:00)

To: [email protected]

Subject: [Test Equipment Design & Construction] slightly off topic feel free to delete

Based on the threads regarding "RF stuff," I suspect many of the members here are experts on RF.

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Please review this design:

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I know just enough to be confused.

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Mr. Martinsen makes a big deal of importance of matching the output of his active antenna design to the impedance of the coax.

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He covers his ideas starting on page 30.

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Many (all?) modern SDRs have a RF impedance of 50 ohms over their frequency coverage. Older, traditional, general coverage receivers exhibit wildly varying input impedances.

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I use a PA0RDT active antenna as my portable test antenna to test the local ambient RF levels.

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I compared 100 feet of LMR-100 Times Microwave coax with 100 feet of Lowe's

Southwire RG6.

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I used Perseus SDR, SDRplay RSP1a, R2000, and Sangean ATS-909 as test receivers.

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I used the Lexington airport NDB and outer marker, local and distant MW stations, WWV, various amateur radio stations and CB (11M in the USA.)

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There was no discernible?difference between coax cables.

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Am I missing something here or is Mr. Martinsen making a mountain out of an anthill?

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?

?

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Hi,

Thanks, ya I have the supplement and I guess I need to rephrase that I am looking for a free one -- sure seems strange as it is just the user manual I cant find although I can get every thing else . hi hi, thanks for the help

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

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

Jeff,

I took the liberty of uploading to your folder a zipped folder that Chuck sent to me a couple years ago.
It contains the description of his B-field loop for RF current sensing.? I hope this is the same set
of documents that you tried to upload.? It appears to have uploaded successfully, but I have not
unzipped the folder to post individual files within it.

73,
Mike, K8CN

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Jeff,

it seems that it never arrived. The folder is there, but it has no files within. Do you want to try again?

Cheers, 73,

Robin, G8DQX

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.

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Watching the second video the new Phillips ultra efficient ones differ significantly from the Dubai lamps in that they do not have a linear built in PSU.

If I ruled the world and were interested in amateur radio then I would ban everything except those that have a linear supply. I would not want the hash from bucks.

Hmm. QO-100 comes to mind.

Just join the dots.

I think everyone has missed the point.

Paul G8AQA

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Hi Michael,

?The 230V RMS is a nominal? voltage. My "230V" supply is 245V RMS on average, a few people get above 250V RMS, some get 230V RMS. It depends on the tap settings in the local substation which are often set up to provide a minimum 230V RMS at the end of the run if they have had reason to swap the taps down from the old setting. People closer to the Substation get a higher voltage which is more stable than the people at the end of the local runs. As most appliances now use switching supplies or drives the higher voltages are reflected in lower current draw but resistive loads obviously draw more current.

?The whole thing is not what many people think, they re-wrote the 240V to 230V -6 +10 % and kept the taps more or less where they were unless someone complained- but very few people are aware of the reality and crudity let alone actually measure the voltage with a true RMS voltmeter long term. My supply has around 2.5% harmonic distortion so the type of rectifier is significant.

However the history is vastly more complicated than you suggest, DC supplies persisted for a long time . Parts of London were on 220V AC ( my parents house was..) before consolidation of different local generators.? Germany has recently suggested a change to DC supplies!

73, Alan G8LCO

Here in West London, UK, we are currently at 248V AC, with a 200mV DC asymmetry.

I have just had a mains filter capacitor blow in one of my pieces of test gear (HP LCR Meter), which I am just about to snip out.

Once I drag myself away from my computer that is!

I don't think you quite right about the 230V and the UK.
There is a good description of the history here:



But to summarise:

Pre-1995: 240 V +6 % / -6 %? (225.6 - 254.4 V)
From 1 January 1995: 230 V +10 % / -6 %? (216.2 - 253.0 V)

Only the spec changed in 1995, no hardware was altered.

MK

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Sorry Mikek,

Missed your reply. In the UK the mains voltage has been increased too, our old 230V is now around 245V - enough to shorten the life of any incandescent bulbs still remaining to 50% . Interesting to note that the incandescent bulb makers had?? secret cartels? ( on both sides of the Atlantic ) that agreed to produce bulbs with nominal lifetimes of 1,000 hours - down from the around 2,500Hrs before the agreement so they sold a lot more bulbs.

Different people give different numbers for the effect of voltage change on bulb lifetimes, the basic relationship is Hr * Vr/Va ^n where n=12 to 16!!! Vr is rated voltage and Va is actual voltage with Hr as nominal lifetime. It does depend on a lot of factors, DC powering about halves life, short surges are very bad as are switch on inrush currents and very small variations in filament thickness that cause higher temperatures in narrow parts that lead to early failure and minute traces of water vapour that causes blackening on the inside of the glass.

Same bad effect for the heaters in? tubes ( Valves) . During WW2? Bletchley Park used computing machines with around 2,500 tubes per machine, there were 10 such machines eventually. They simply left the machines running all of the time.

73, Alan G8LCO.

On Sat, Feb 25, 2023 at 05:44 AM, Alan wrote:

Much simpler and cheaper to use a 120-12 VAC step down transformer,? put the 12V winding in series with the line to reduce the supply to the old voltage if the equipment does not have a 125V input tap. Obviously you need to get the 12V to subtract not add!

I thought that is what I said!
???????????????? Mikek

Much simpler and cheaper to use a 120-12 VAC step down transformer,? put the 12V winding in series with the line to reduce the supply to the old voltage if the equipment does not have a 125V input tap. Obviously you need to get the 12V to subtract not add!

73, Alan G8LCO

I put up 11 pictures of recent progress on the two-stage transformer. I'm calling it a done deal for now, until I get around to final driver amplifier design and construction. The transformer design is now set with T1 primary at 18 turns 22 AWG bifilar, series connected. With the 4.5:1 T2 ratio, it's about 162:1 overall, so Z ratio about 26,000. Fed from my test circuit (in 25 R mode hookup), the output Z magnitude should be about 1 milliohm. After some study and design of the overall system using the 8568B and TG for dBQ display as I mentioned before, I have determined that a fixed output level around a mV is sufficient, so a modest amplifier is needed, rather than a much higher-powered one I had pictured before. The desired signal level is attainable without any amplifier, from the TG, which provides just a little over 0 dBm in 50 R, but I'll put in some gain to allow for more margin, and to reduce the driver (and hence output) Z a lot more, which also will drop the lower cutoff frequency to around 5-10 kHz.

The pictures are mostly self-explanatory, and I'll add lots of details next time. The main thing is to note the wide BW and good flatness, and the very low output Z that can take an almost dead short - me pressing a wad of copper mesh against the post and bushing as hard as I could without hurting my thumb - and dropping only about 10 dB, and still very flat at all frequencies. There is one oddity in the 1 dB/div picture. The dip around 7-8 MHz I believe is an artifact of the TG due to mismatch in the test circuit. Changing the cable length here moves it around in frequency. It should (hopefully) disappear after the amplifier is in the system.

BTW I probably should have made a new album for these, to avoid confusion with the older version and pictures. When I went to do the upload, I thought I could make a sub-folder inside, but could not figure it out.

Ed

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@...>