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Messages - redhat

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76
They pop up at hamfests and the like here, usually in the $200 US range.  I picked up a broken one a few years back for $150 or so.  I have two I use for testing and monitoring.

+-RH

77
10KW on 620 KHz is far from pathetic.



Anything that covers Milwaukee to Green Bay is doing pretty good, and that includes a good chunk of Wisconsin's large population centers, Madison aside.

+-RH

78
Based on my experience using tape measures for ground radials, I'm not sure I would do this.  The cheap ones have a tendency to tear when under tension, and especially as they rust in the weather.

+-RH

79
General Radio Discussion / Joe Farley, one of our own, has passed
« on: March 09, 2022, 1746 UTC »
I got word a few weeks ago from his wife that Joe had underwent surgery for brain cancer and was on hospice.  O.P. was digging around last night and found this..
https://www.adamswinterfieldsullivan.com/obituaries/Joseph-A--Farley?obId=24206974#/obituaryInfo

Myself and Zane met up at Joe's place in 2014 to hang out, and we used to chat on the phone from time to time.  I wish his family the best as they navigate this rough time.

I still have one of his loops on my roof and use it!

+-RH

80
It could be a fluke, but I noticed this afternoon that Sputnik is missing from Galaxy 19.  RT is still up there however.

RT has been pulled from DirecTV.  Sputnik is still on the air in DC via 1390 AM.

As of 3/4/2022 RT is no longer on Galaxy 19, just a still picture.

+-RH

81
Equipment / Re: Question about ordering aluminum tubing
« on: March 02, 2022, 0422 UTC »
We have a local vendor that sells aluminum tubing in telescoping sizes.  Both my verticals run on this stuff, and its what I would recommend.  Shipping will kill you price wise, so look for a local vendor.  In most cases, some ham supplier outlets can point you in the right direction.  I think it cost me about $150 in tubing to build my current 55' vertical, not including the base and feed components.

DX engineering is VERY expensive for what you get.  If you don't have any machining skills or tools though, it may be one of the few options.  About the only thing I buy from them is their vertical base assemblies, and the buggers don't even include the mounting bolts!

+-RH

82
https://www.broadbandtvnews.com/2022/02/28/eu-issues-ban-on-russian-tv-channels/

Quote
The European Union is to ban the Kremlin-backed talk channel RT.

In a series of moves announced on Sunday, European Commission President Ursula von der Leyen said the EU would ban RT (Russia Today) and the news agency Sputnik.

“Russia Today and Sputnik, as well as their subsidiaries, will no longer be able to spread their lies to justify Putin’s war and to sow division in our union. So we are developing tools to ban their toxic and harmful disinformation in Europe.”

As also reported by Broadband TV News, a campaign led Ukraine’s Ministry of culture and information policy, and supported by leading Ukrainian media groups – 1+1 media, StarLight Media, Media Group Ukraine, Inter Media Group has written to operators asking them to pull the plug on any Russian news channels broadcasting over satellite, cable and OTT.

A number of countries have already taken their own action at both national and operator level. Poland and Latvia were early movers. However, the UK is waiting on the outcome of an Ofcom investigation into RT.

Wanna bet we see more SW in the future?

+-RH

83
The RF Workbench / Re: Hellschreiber beacon - with some oomph!
« on: February 28, 2022, 0144 UTC »
IF the first waveform is the drive to the fet, the duty cycle is WAY too high.  It should be closer to 40-50%.  This has a large effect on your efficiency, and thus heat load on the final device.  This is one of the reasons I use purpose built fet drivers in PA applications, better control over drive.

+-RH

84
I see this popping up in threads around here from time to time, and it bears repeating.  To eliminate problems in your builds, especially as beginners;

*Don't buy components off ebay, or Aliexpress, wish, etc.  This is especially true of vendors overseas.  Many times these parts are restamped low quality parts of substantially different rating than they claim to be.
Buy parts from reputable domestic vendors, like Digikey, Mouser, etc.  It may seem daunting, as there are usually many versions of a particular part, but if you don't know which one will work, ask for help here.  We'll do our best to help you sort them out.

The money you think you will save is usually lost chasing problems related to counterfeit parts.

+-RH

85
Starting to get some copy on the local SDR.  Good on Chris's 120 footer @ 2348 with 'Traveling Through The Night'
Appreciate the shout @0010z!
Starting to get some better peaks locally as of 0020z.
Live break with DJDW @0023z.  Sounds like He went QRT.

Thanks for the show!

+-RH

**Posted this by mistake on another thread...oops.

86
The RF Workbench / Re: Hellschreiber beacon - with some oomph!
« on: February 24, 2022, 2151 UTC »
Buying semi's from ebay is extremely risky, particularly with suppliers from overseas, China specifically.  You never know what your going to get.  Always go with a mainline distributors where possible (Mouser, Digikey, Newark, etc).  Whatever you think you will save in money will surely be lost in time and frustration.  These are jellybean parts, buy the proper ones from the start.

+-RH

87
The RF Workbench / Re: Variable frequency oscillator design for HF
« on: February 24, 2022, 1804 UTC »
The AD9833 is one easy way to break free from fixed crystals. I have one on the bench and use an Arduino "Nano" board to control it. There's lots of software already available. It's easier to use the square wave output and filter it as the board's  sine wave out is fairly poor quality.

If you want something you can just use without software and a microcontroller there are modules with everything on the board to allow it to act as a VFO. Depends on your skills and budget as well as what you define as simple

Thats what I'm using.

I ordered a few last month, and hope to play with them more once I get some rotary encoders (which are not included!)

+-RH

88
The RF Workbench / Re: Hellschreiber beacon - with some oomph!
« on: February 22, 2022, 0743 UTC »
Maybe so, and I'll be the first to admit that I can be a stick in the mud.  Its kinda like the old addage, stick with what works.  I've gotten to a level of satisfaction with my current rigs that simulation for me is uneccessary.  It may be true that it would have saved some design time in the beginning getting things to behave, but my methodology seems to work for me most of the time.

I've also seen my share of EE's that couldn't design a hole in the ground.  They would get all wrapped up in modeling something, yet their builds never worked.  You need a good balance of intuition and experience to make things play nice on the first try.

+-RH

89
The RF Workbench / Re: Hellschreiber beacon - with some oomph!
« on: February 18, 2022, 2119 UTC »
Something is very wrong if all you can get is ~25% efficiency.  Even my non-optimized CMCD PA's with asymmetrical drive get north of 83% DC-RF efficiency.  Also, keep in mind that all mosfets exhibit a dramatic shift in output capacitance v. Vds.  This can cause tuning problems and a shift in efficiency over the power range, notably on the bottom where voltage excursions are closer to zero.  This can cause a host of problems, among them IPM (incidental phase modulation) which causes problems for complex modulation modes like DRM, and C-QUAM.  This is one of the reasons I try to swamp out the shift in Cds with large tank capacitances.

Per the previous comments; I've seen in my limited experience people go to the ends of the earth to try and optimize a PA, only to get less performance than circuits I tuned empirically.  Usually this is due to circuit strays that are unknown, or unaccounted for in the simulation stage.  This could also be the source of at least some of your difficulty in getting this circuit to behave.

The 180 degree shift is to be expected, as the instant the Vgs exceeds the turn on threshold, the fet will begin to conduct and pull the Vds toward zero.  I would probably explore a different driver for the fet and I imagine some of your efficiency problems will go away.

It should be also noted that measurement accuracy becomes more and more of an issue when measuring the output of these newer higher efficiency PA's.  At some point you have to figure out whose lies you believe.

+-RH

90
The RF Workbench / Re: Hellschreiber beacon - with some oomph!
« on: February 17, 2022, 0727 UTC »
My biggest problem with this paper and this circuit is that to specify a Class-E output network as he has without specifying a transistor is somewhat misleading; it fools the user into thinking that they can plug any old transistor (even a MOSFET) into it and expect it to work. Maybe this would work at 50 KHz with old power MOSFET transistors (which tend to have humongous output capacitance that swamps any other performance differences between models of transistors) but not at 6.9 MHz (as in the paper). The reality is more complicated and the component values of a Class-E network absolutely have to be tuned and optimized for each transistor at each frequency.

This is the primary reason I'm sticking with CMCD.  The design process is as simple as tuning the tank to resonance and going about your day.  In theory you could precisely calculate the tank values taking into account the Cds and so forth, but I found it much easier to spitball it.

+-RH

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