Messages

136

Amateur Radio / Re: TX noise figures from today's HF transceivers?

« on: April 19, 2021, 2322 UTC »

The only splatter I hear when surfing the bands are those running dirty linear amplifiers.  It also seems to follow that there is little "intelligence" modulated on these dirty signals.

+-RH

137

The RF Workbench / Re: Building an HF amplifier

« on: April 17, 2021, 2022 UTC »

FWIW, you could buy one of the many kits off ebay such as... https://www.ebay.com/itm/MRF300-LDMOS-600W-HF-LINEAR-AMPLIFIER-1-8-54MHz-BOARD/233929540038?hash=item36774981c6:g:dYMAAOSwwkhgQO9Z

Just supply fets, heatsink, and off you go.  600W fairly simple as all the hard work is done for you.

BTW you can do high level SSB using the kahn method.  Continental and others have been doing it for over 30 years...without DSP, and at hundreds of KW.

+-RH

138

The RF Workbench / Re: Building an HF amplifier

« on: April 17, 2021, 1815 UTC »

I'd stick to the BLF188XR as you can get an easy 800W from 5W driving. The 200W kits with IRF devices are fairly old designs and not the best.

Depends what you're looking for?

Band switching is the most problematic part!

Str.

BLF188/184 are now EOL pending replacement devices which have yet to be released.  I found that out repairing a 5KW FM recently.

Also keep in mind unless you are willing to solder the devices to a heatsink, the newer gemini devices are totally unsuitable for full limit linear service.  Lots of power in a small space, a thermal management nightmare.

+-RH

139

North American Shortwave Pirate / Re: X-FM Relay 5185 AM and 4180 USB 2300 UTC 16 Apr 2021

« on: April 16, 2021, 2355 UTC »

Thank you Red Hat. Do you have any Beyond the Horizon or Pusifer???

Yes...coming up!

Special thanks to MRI and RI for making this happen tonight!

+-RH

140

General Radio Discussion / Re: Looking for a Volunteer Or Two

« on: April 11, 2021, 0353 UTC »

Thanks for your efforts Skip!  Also, thanks to Chris for giving us this playground in the first place

+-RH

141

General Radio Discussion / Re: Pirates helping communities during COVID?

« on: April 06, 2021, 0252 UTC »

While not technically a pirate, I was made aware of several temporary tis style stations licensed through Ntia for information about covid testing locations and directions.  Most were associated with hospitals, churches, and community centers.

+-RH

142

Equipment / Re: Interesting Chinesium SI4732 Shortwave/Air/FM

« on: April 02, 2021, 0356 UTC »

Why the interest in this, form factor perhaps?  I would guess this is the chipset used in all the Chinese cc radio clones?

+-RH

143

Other / Re: OTHR on 40 Meters 2339 UTC 29 March 2021

« on: April 02, 2021, 0349 UTC »

I'm sure you know this, but the 7200--7300 Khz spectrum is only available to amateur radio users in ITU region 2, North and South America.  The rest of the world recognizes this segment as a broadcast band.
...just in case some folks don't know that.

+-RH

144

North American MW Pirate Radio / Re: Radio Italiano / Throwback 90s ? 0025 UTC 31 Mar 2021

« on: April 02, 2021, 0331 UTC »

Frequency?

+-RH

145

General Radio Discussion / Re: Supreme Court sides with FCC in loosened Media Ownership rules

« on: April 02, 2021, 0329 UTC »

I also heard through the grapevine that ihateradio is making large cuts to engineering and programming.  Some engineers are now tasked with keeping 50 or more signals on.  There is also rumors that the format lab is back again with a new twist....audio will now originate from a system at the transmitter.  All stations running the same format will run the same log, coast to coast.

This comes on the coat tails of a UK company now controlling almost half of the company.  The end is nigh.

+-RH

146

SDR - Software Defined Radio / Re: Requesting an SDR Recording of WWFD-AM Radio, Frederick MD

« on: March 19, 2021, 1841 UTC »

An AM allocation includes 10 KHz of modulation each side of carrier.  Per the NRSC 5 description of mode MA3, there are two modes; standard mode which includes the primary and secondary digital sidebands (18.4KHz total), and a reduced digital mode which includes only the primary digital sidebands (9.81 KHz total).

This is outlined in NRSC 5 found here. https://www.nrscstandards.org/standards-and-guidelines/documents/standards/nrsc-5-d/reference-docs/1012s.pdf

+-RH

147

Equipment / Re: Looking for Linear Power Supply

« on: March 11, 2021, 0100 UTC »

I saw the pics...I wouldn't put that on the air if I were you.  It also isn't built with enough heatsink to be reliable.

148

The RF Workbench / Re: Help with 22m beacon kit from Black Cat Systems

« on: March 11, 2021, 0000 UTC »

My money is on a bad IC.  It probably got zapped when you built it...I've had similar happen with CMOS devices.

+-RH

149

Equipment / Re: Looking for Linear Power Supply

« on: March 10, 2021, 2339 UTC »

here are the Specification :

Power Input       =  30-100 Watt SSB
Output Power    =  800 Watt
Voltage              =  17-20 Vdc
Transistor          =  8 units IRFP150N  ( Many in Ebay for $ 2 each )
Frequency         =  2 Band 3,5-14 Mhz,
                              3.8Mhz = 600 Watt , Peak
                              7 Mhz = 800 Watt.  Peak Power
                              11 Mhz = 500 Watt, Peak
                              14 Mhz = 300 Watt , Peak

Oh god no...

Do the innerds look like this?


Another piece of sound advice...don't buy semiconductors off ebay.  Many times the devices are restamped versions of smaller devices and they will fail prematurely...especially if the come from overseas.

+-RH

150

Equipment / Re: Looking for Linear Power Supply

« on: March 10, 2021, 2335 UTC »

I think we're more interested in the amplifier itself, i.e. why the strange voltage requirement.  Most stuff is going to expect either 12 or 24VDC for supply.  I've never seen anything RF related that required 18-20VDC.
+-RH