Powerwerx SS-30DV switching power supply – RFI hash noise across all HF bands

Continuing rebuilding the shack. Since hamfests are off-limits due to pandemic restrictions opted to buying brand new equipment on a budget.

Bought a new Yaesu FT-891 which while by all means is not a great performer is a portable and a budget option for a portable/mobile/base station and could be a good choice of a Field Day radio.

HRO had it on sale and also listed Powerwerx SS-30DV as a recommended accessory PSU among slightly more expensive Yaesu FP-1023 (also switching type aka rebranded Samlex SEC-1223) and a more expensive linear Yaesu FP-1030A.

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Staying connected with ZUMSPOT hotspot

Could not miss a good sale on Hamradio.com and bought a Zumspot w/1.3″ OLED kit for the shack. I also bought an acrylic case for it.

IMG_20200425_142734

It took more time to find a small screwdriver than putting the kit together. Basically, you just need to put 4 tiny bolts (included) through the holes in the case and the Pi board, add spacers, and then insert the radio board (with the antenna) into Pi’s GPIO connector:

IMG_20200425_142921

Took less than 5 minutes altogether to assemble:

IMG_20200425_143058

The SD card included with the board had Pi-Star software installed on it which saved time downloading and flashing the card.

It took a bit longer to wrap a head around the software configuration and much longer learning about all the talkgroups / reflectors / etc. though.

Toshen, KE0FHS has put together a good guide covering configuration of the hotspot which was very helpful. Here is a copy, just in case.

Basically, the gadget is a small internet-connected digital repeater located at a comfort of your home. Once you put your WiFi network details in it, your callsign and the operating frequency, you need to figure out which of the digital networks to connect it to.

Presently, it seems the most active ones are:

  • DMR (Brandmeister) talkgroups
  • Yaesu Fusion WiresX
  • D-Star reflectors

Both DMR and D-Star require registration. DMR (Brandmeister) was the easiest to register. The admins approved my registration in less than an hour once I confirmed my email. I am still awaiting for my D-Star registration after 2 weeks I submitted it….

You need a matching handheld in order to operate these digital modes since audio encoding/decoding is performed by the handheld hardware / firmware.

Actually, there are software codecs that work with DMR and Yaesu Fusion standards but not with D-Star (due to license restrictions).

As a result, you need a D-Star HT to use D-Star reflectors. At the same time, you can use Yaesu Fusion radio to operate both Yaesu Fusion and DMR networks because they both use the same newer codec for audio encoding/decoding allowing cross-network bridging of talkgroups.

Presently, I am using Yaesu FT-70DR digital dual-band radio from HRO for accessing DMR talkgroups via the hotspot using YSF-to-DMR functionality.

FT70_on_DMR

The closest real world analogy to this hotspot technology is a simplex VOIP conference call with the last mile delivered over a radio link. Basically, it’s good ole Echolink with an HT instead of a headset. The medium for communication is the internet – not ionosphere, making communication reliable and simple (as long as the internet is available).

The talkgroups (DMR) / reflectors (D-Star) are a digital analog of a dedicated talking radio frequency. They seem to be mainly grouped by a geographical location. Some link several repeaters together. Some are special purpose: e.g. SKYWARN, etc.

Given the decline in a number of operational repeaters and aging of the hams, these little hotspots provide an affordable option to communicate with fellow hams without a challenge and expense of HF gear and antennas. I dialed my Yaesu Fusion radio to DMR talkgroup TG9 (World talkgroup) and it’s busy with hams chatting from all over the world.

It’s amazing how technology erases artificial borders and makes this world a smaller and a better place.

73!

Shipwrecked

Apologies for the extended absence. As some of you know, the last 2 years I was working hard at work while rebuilding a new QTH on a tropical island investing all my spare time and resources in it.

Ironically, a week after all the hard work was finished, hurricane Dorian came along and destroyed our QTH and most of the island with 185mph+ winds and 11 feet of storm surge taking hundreds of lives and leaving little behind. All the hard work, gear, personal items, everything, got soaked or carried away by the ocean and whatever survived, got carried away by looters.

Thankfully, I left the island a few days before the storm hit. Whatever was in my carry-on bag with me are the few possessions that survived. Unfortunately, ham radio gear wasn’t.

dorian

It will take years (if not a decade) for the life on the island to become normal again (if ever). The current goal is to find a new QTH, regroup, and try to rebuild our lives again.

73!

Mobile shack

Happened to be in W4 (Florida) this winter so I took my FT817 with me. Thanks to reciprocity between Canada and the US, I can operate using my Canadian callsign while in the US.

Being in a car country, it looked sensible to me to set up a mobile shack. My VE3 elmer has had a great success with MFJ miniature hamsticks mounted on the trunk of his car so I started looking in that direction too.

After quick research on what’s available at HRO online, I ordered two versions of MFJ hamsticks: miniature 3′ and longer 7′ hamsticks for the most popular bands. For the base, I ordered a mighty MFJ-336T mag mount with 3/8″ mount.

The first one to arrive and to install was MFJ-1620 – 7 feet tall antenna for 20m. The fiberglass base is about 4 feet long and is hollow inside. A stainless steel whip that screws on top is adjustable.

MFJ-1620

When fully extended, it resonated nicely on 13.540 MHz (perfect 1:1 match!) which was way too low… After shortening the whip by about 4″ the center of resonance shifted towards 14.060 QRP CW frequency (with the lowest SWR about 1:1.2). Could not get it match 1:1 anymore.

The whip is very hard to cut. After some trial and errors, the best tool happened to be a triangular file. Cut through the steel half-way then snapped it easily.

While busy with all this hard work, I did not notice it got really dark outside and the 20m band faded away. After scanning back and forth, a weak but workable signal of ZL3GA emerged and my tiny 5W signal just barely made it across the Pacific (7,220 nautical miles!) . Not bad for QRP with a mobile whip!

The 40m was alive and kicking so the next one to install is a 7 MHz hamstick.

The length of the whip makes driving a bit difficult – have to watch out for clearance, low hanging tree branches, etc. Also, at speeds of more than 45 mph, the whip starts buzzing in the wind.

Photo of my new mobile shack:

Mobile QRP

Hope to see you on the air!

73s,
Paul

Chinese QRP VHF-FM radio restoration – continued

The replacement transistors BG1, BG2 (3AA9, 3AA7) are obsolete and next to impossible to find as it’s been 40 years since the radio was built. However, given the known voltage/power/frequency parameters and a friendly help from experienced radio-engineer ham, a reasonable replacement was identified: 2SA1930 from digikey.

Later, I found more data online at http://www.114ic.com/

Model: 3AA7 Model: 3AA9
Manufacturer: China semiconductor companies
Production of materials: Ge-PNP
Nature: RF / high-frequency amplifier (HF), power amplifier (L)
Package: in-line package
Limiting Voltage: 35V
Maximum current allowed values​​: 0.5A
Maximum operating frequency:> 120MHZ
Pins: 2
Beta: 30
Maximum power dissipation: 5W
Possible substitution: B772
Manufacturer: China semiconductor companies
Production of materials: Ge-PNP
Nature: RF / high-frequency amplifier (HF), power amplifier (L)
Package: in-line package
Limiting Voltage: 25V
Maximum current allowed values​​: 0.5A
Maximum operating frequency:> 120MHZ
Pins: 2
Beta: 30
Maximum power dissipation: 5W
Possible substitution: B772

The parameters were exactly as predicted. After installing new transistors, the radio came back to life. However, predictable the output power is too low – less than 100mW.

The bias/feedback seems to be wrong as the bias voltage is different for silicon (0.6V to 0.7V for silicon vs 0.2V to 0.3V for germanium). Also, the operating frequency (50MHz) is too close to the 200MHz limit which also limits the gain.

It may require readjusting the circuit / voltage dividers to ensure proper bias and gain.

While googling the radio, I also found some decent translation of the operating manual: 884_manual_translation

As the radio works on 45-50.1 MHz, it only slightly touches the lowest CW portion of the amateur 6m band. Re-tuning it to 50-55 MHz may not really worth the effort so I may put it on eBay. Would be nice to fix the finals though first.

The full schematics are here:

884_p1

884_p2

 

 

New Year resolutions / to do list for 2013

Merry Xmas and Happy New Year everyone. On this post I’ll try to summarize the goals for 2013:

  1. Build permanent shack, install antenna distribution box, new grounding system, antenna feed lines, dedicated PC for digital modes / DSP / CW / logging,
  2. Install antenna distribution box outside, improve lightning protection, grounding system at the entrance

Antenna projects:

  1. Build 10m halo antenna for digital modes, portable use
  2. Build 20m magnetic loop antenna for digital modes
  3. Install new grounding and radials to the main vertical antenna, weatherproof distribution box, retune antenna, calculate diagrams (EZNEC), bury new feed line in a rodent-proof conduit
  4. Locate and identify source of S7 QRN on 40m
  5. Build new HF / VHF antenna
  6. Build and install discone antenna on attic with remote RTL-SDR / Raspberry Pi receiver
  1. Finish SoftRock RXTX kit
  2. Convert Softrock 20m lite for WSPR / PSK usage
  3. Build WSPR beacon
  4. Build APRS gateway using Raspberry Pi
  5. Finalize MCU homebrew paddles CW-keyer (add enclosure, paddles)

Shack updates

The shack updates:

1. I am considering ordering Ameco K-4 Brass Key AM-K4 – it’s $24.95 at http://www.mtechnologies.com/ameco/keys.htm

It has some good reviews (4.8/5.0 score) at http://www.eham.net/reviews/detail/3383
I will most likely add a solid heavy thin base to it or simply attach it permanently to the desk.

2. For my Softrock, I am going to build a simple magnetic loop. This place happens to have inexpensive variable air capacitors ($10-20) that I am going to try for this: http://midnightscience.com/catalog5.html#part3

3. My new LDG S9v31 vertical is behaving strangely. The SWR which was close to 1:1 on most of the bands now is 1:1.5 or 1:2 at best. I guess the change of weather changed the electrical qualities of the soil so I may need to try elevated radials. I think I also need to borrow an antenna analyzer to check the actual impedance and resonant frequency before and after the 4:1 unun. Update: it’s back to normal now.

I came across some interesting links related to ham radio:

Changes in the shack

Finally installed a new vertical antenna – LDG s9v31.
http://www.eham.net/reviews/detail/8067

The antenna seems to be performing quite well on receiving. The SWR on 40m and 80m is close to 1:1 (with tuner of course), and is close to 1:2 on higher bands. Not so good on transmit, probably, because I only have two radials for now which is definitely not enough.

The old mic which came with the rig was in need of replacement so I ordered a replacement MFJ mic for $25. Shipping was $20 on top and took 2 months to deliver… Once it finally arrived, the wiring was loose and not secured to the connector so it shorted right out of the box… ah well… Took a soldering iron and rewired it. Seems to be working okay now.

Other updates – got my first QSL card from my first DX Italian contact. That was a very nice surprise for the New Year.

Kenwood TS-520 classic rig

Went to a ham radio garage sale in Newmarket and now I am a happy owner (the third owner) of a wonderful Kenwood TS-520 hybrid rig (SN#250226) – thanks to VE3NX (was the second owner).

The rig is very clean and seems to be in great shape!

Also, thanks to VE3IZZ, who practically donated to me an MFJ-941E tuner and a 20m dipole along with coax cables. Thus, by 7pm I was dipping plates and CQ DX!

One problem though – the tuner has no internal dummy load. That I discovered a little late.. after tuning the rig a couple of times… but seems like luckily did no damage to the finals.

So I ordered 20 x 1000 Ohm 2W carbon resistors on eBay to build a dummy-load myself.

K4EAA has provided great building instructions on his wonderful website dedicated to Kenwood hybrids: http://k4eaa.com/dummy.html

Kenwood TS-520 Manual