Messages

706

General Radio Discussion / Don Baldwin aka Rockpicker has passed away

« on: February 08, 2018, 0106 UTC »

I got an email back from his wife Margie this afternoon after sending out QSL's and she told me he passed last November.  I offer my sincerest condolences and suggest we all raise a glass to a fellow friend and DX'er.

He was one of us, and Margie told me to tell everyone here he loved us all.

https://www.afterlife.co/us/obituary-coffee-creek-don-f-baldwin-6435055

+-RH

707

For Sale / Wanted / Barter / Re: 'It's like Frankenstein's lab': Massive 78-year-old transmitter for sale

« on: February 07, 2018, 2300 UTC »

..and a few cases of the handymans' secret weapon...duct tape.

+-RH

708

Equipment / Re: WOw, for those with $$ to burn

« on: February 02, 2018, 2006 UTC »

Yawn!

https://www.youtube.com/watch?v=1K8LHVRrESE

This is what you want for an HF (SSB) linear.

ALL somewhat old hat really.

I must say I'm becoming somwhat tired of ALL this, 'Look at what you could build' stuff.

Build it then!

It actually not that easy getting it all stable and reliable and reproducable BTW!

Str

Moan over.......

+1

709

Equipment / Re: Grounding systems

« on: February 02, 2018, 2005 UTC »

The Nautel approach is the gold standard and it works well if you do it right.  Basically bond everything you can together and tie it to a common earth ground preferably all at the same physical location.  The things you can't bond, ferrite the Sh-- out of!  Per their mantra, use the ferrite with the highest permiability and the lowest cutoff frequency you can get.

A later version of the same paper covers a few more areas that are still relevant to SWL stations.

http://www.nautel.com/wp-content/uploads/2011/04/Transmitter-Site-Preparation-Recommendations-Sep-2004.pdf

+-RH

710

Equipment / Re: WOw, for those with $$ to burn

« on: February 01, 2018, 2354 UTC »

27 MHz is an ISM frequency for induction heating.  I've seen tube based stuff in that neighborhood in gas spectrometers used for materials analysis.

List price is $225 per device, about double what you'd pay for a proper MRF151G with 4-5 times the power.  That's not a bad price point.  I'm not sure if you could get that kind of PEP from the device in linear service due to thermal limitations, but an interesting thought exercise.

+-RH

711

General Radio Discussion / Re: Broadcasting in SSB many advanategs a few disadvantages

« on: February 01, 2018, 1921 UTC »

Again, they have the technology and still maintain a network of monitoring stations.  They know where we are in most cases, but my guess is, they don't have the resources to chase everyone, just those they perceive to be a threat to themselves or others.

+-RH

712

The RF Workbench / Re: Power Supply for TX

« on: February 01, 2018, 1918 UTC »

But then again your dealing with hams, most of which these days don't know how to fix anything (appliance operators).

+-RH

713

The RF Workbench / Re: Amperage of Fuse in Streachy Lunch Box

« on: February 01, 2018, 1917 UTC »

You can get a 'big eye' (magnifier with light and desk arm mount) for about $60. I have one but rarely use it.  Often I use just the loupe and a MR16 LED lamp if I need a real good look at something.

+-RH

714

General Radio Discussion / Re: Broadcasting in SSB many advanategs a few disadvantages

« on: February 01, 2018, 0347 UTC »

Man I would love to see that schematic for the final PA's

Its 640 of these.  4 NX400's into a combiner.  Each transmitter is 4 cabinets with 40 modules per cabinet.  Each module is good for something like 4 KW, in normal service they run around 2.5KW carrier.  Conventional class D with non-overlap circuitry included in the module.

http://www.nautel.com/solutions/high-power-mw-nx-series-100kw-2mw/

+-RH

715

The RF Workbench / Re: Amperage of Fuse in Streachy Lunch Box

« on: February 01, 2018, 0335 UTC »

I've had good luck with a loupe on parts as small as SC-70.  1206's, SOIC's and other stuff I can do without magnification, but you still need it for inspection, looking for solder bridges, etc.

+-RH

716

General Radio Discussion / Re: Broadcasting in SSB many advanategs a few disadvantages

« on: February 01, 2018, 0049 UTC »

Red Hat, the sharks could strike, but frankly they need a compliant. FCC doesn't do squat without a compliant.

Sure they could, and historically, you either needed to be in the wrong place at the wrong time (it happens) or do something stupid, like broadcasting for long stretches from an urban residence.  That is why I built my station to be easily movable.  Pack up the gear and go...across the state or 6 states over.  No big deal, all I need is a back lot and we're good to go.  Parks, fields, or an abandoned parking lot.  All good candidates.

We may get it one day.  It happens to a lot of guys after a while.  Its the risk you take to play the game.

Also, I am shocked that 500kw transmitters exist. Can you imagine paying for an extra 250 kw and get half an S point.

Nautel just lit up a 2MW AM in Hungary I believe, and a 400KW on 800 KHz in Bonaire.  Someone is buying these things.

+-RH

717

General Radio Discussion / Re: Broadcasting in SSB many advanategs a few disadvantages

« on: February 01, 2018, 0014 UTC »

Those are called feeder transmission, used to carry programs to distant relay stations in ISB.  It was mostly used before satellite became common, and is still sometimes used as a backup solution should the uplink fail.

I honestly think the FCC has better things to do than police large swaths of HF spectrum.  They know we're here.  Just listen to the 'licensed' ham bands and you tell me if there is much enforcement going on.

Most receivers have bandwidth controls.  Run 5-10 KHz audio, and let the listener decide what they want to hear.  Don'f forget there is a law of diminishing returns with regard to transmitter power.  You have to dump a lot of watts into the sky to get another S unit, in most cases it's not worth it due to the stress placed on everything from the transmitter and what is powering it, to the feeder and antenna networks.

I still run 10-13KHz audio.  At least give the listener the choice to decide how good or poor they want it to sound.

+-RH

718

Equipment / Re: The best undercover fm antenna on the market

« on: January 31, 2018, 2301 UTC »

Back in the day I had a lot of trouble building FM antennas that would resonate anywhere close to the design frequency.  The trouble I later discovered was something called K factor.  The larger the diameter the radiating element, the shorter the element needed for resonance.  There is a chart in one of the ARRL handbooks that has a table.  I seem to recall with 3/4" pipe at FM frequencies, around 93% of the free space length is required.

This applies to HF too, but usually unless you are using a large face tower, the effect is pretty small.

I never liked groundplane or 5/8 wave antennas at FM, I've always found their radiation patters to be too elevated to be useful.  Again, a lot of your hard earned power is going up around 30-45 degrees above horizon, not real useful.  They also radiate some secondary lobes that can cause multipath problems.

Dipoles are less trouble anyway.

+-RH

719

General Radio Discussion / Re: Broadcasting in SSB many advanategs a few disadvantages

« on: January 31, 2018, 2253 UTC »

Back in my SSB days, I can count on one hand the number of airchecks I received that were on the correct frequency.  If your listening to music that is unfamiliar, it is very difficult to get the frequency right.  Agreed, frequency standards would fix the problem, but most receivers are not that stabile to begin with.  AM with a good sync detector, or DSB with some carrier leak is a good compromise between fidelity and the ability to correctly tune.

I'm sorry but 3K doesn't cut it for me.  If I wanted to listen to music through a telephone I would.  Set it for 10 KHz and let the listener decide how much noise they want to listen to.

+-RH

720

The RF Workbench / Re: Amperage of Fuse in Streachy Lunch Box

« on: January 31, 2018, 0227 UTC »

  This is a tiny fuse. If its marked it will take a magnifying glass.

A necessity for every bench, especially with the SMD stuff.

A five pack at Harbor Fright will set you back a whopping $4 https://www.harborfreight.com/5-piece-loupe-set-98722.html

+-RH