Within the last couple weeks, my 50A Sorensen instrument power supply has been giving up the ghost. If I would draw anything more than a 19A load, the radio would start to output hash all over the band, generating a recklessly wide signal on CW. I must say, not very good amateur practice. Since then, I’ve been looking around for a solid power supply, even finding a nice 35A rack mount Duracom at a local hamfest for $75 which I ended up kicking myself days afterwards for not buying.

My search ended while browsing some eBay auctions and was instantly introduced to the Chinese OEM-type switching supplies used in various devices and appliances. The prices were very reasonable, 30A supplies for approximately $50. How good could they really be?

I remembered hearing something early on about switching power supplies causing interference in the shack, or generating hash so loud, it would cover-up the reception of weak DX stations. I immediately started my search on eHam to see if anyone else had attempted using similar supplies and expected to hear the usual horrific war stories. I was surprised to hear something positive on the subject with many hams having gone the same direction.

Here’s a link to one of such discussion threads:
http://www.eham.net/ehamforum/smf/index.php?topic=71829.15

With that in mind I found an eBay auction for 2 units and purchased both.

View at Picasa Chinese Power Supply (S-350-12)26-Oct-2011 22:30, Apple iPhone 4, 2.8, 3.85mm, 0.067 sec, ISO 160

View at Picasa Chinese Power Supply (S-350-12)26-Oct-2011 22:30, Apple iPhone 4, 2.8, 3.85mm, 0.067 sec, ISO 200

Upon wiring up one of the supplies with Anderson power-poles leads for output DC and the stripped back end of an extra computer power cord for the input AC, I was ready to unleash my abuse. Below you will see my findings tested with a power meter used for troubleshooting electric RC airplanes. The meter displays voltage, current draw, watts and amp hours and has been a very sought after tool in my shack. I highly recommend picking one up.

The first photo shows current draw on one supply leg of a 200w Kenwood TS-480HX at 100% duty-cycle, full output. Current draw measured was 19.5A.
The second photo captures nominal output voltage of 13.24V at minimal load. 1.2A was measured with the radio on and idle. This was the maximum voltage I could get out of this supply.
The third photo indicates the voltage drop with a 19.5A load. Output only dropped .25V.

View at Picasa TS480HX Single leg current draw at 200 watts26-Oct-2011 22:16, Apple iPhone 4, 2.8, 3.85mm, 0.067 sec, ISO 200

View at Picasa Voltage, minimal load, 1.2A idle26-Oct-2011 22:16, Apple iPhone 4, 2.8, 3.85mm, 0.067 sec, ISO 160

View at Picasa Approximate .25 voltage drop at 19.5 amp load26-Oct-2011 22:16, Apple iPhone 4, 2.8, 3.85mm, 0.067 sec, ISO 200

OK so it looks like the supply will do 20A fairly easy. But will it output it’s rated 29A? I was able to draw the radio’s maximum current draw from just one supply. This is probably a bad idea but it does seem to do it.

View at Picasa 26-Oct-2011 22:56, Apple iPhone 4, 2.8, 3.85mm, 0.067 sec, ISO 160

In addition to testing the supply on the bench with an oscilloscope (which output a clean DC trace), I also tested it with the 480HX at full output on CW. Not a hint of RF hash was detected.

I’m only a couple days on the new supplies and I’m very happy with my decision to go this route. The RF hash issues with these types of supplies seems to be a thing of the past. Long gone as the technology has gotten better. However I did notice a voltage output difference between the two units I bought. One of them outputs 14.8V max and the other 13.6V. This doesn’t seem to be all that critical for this application, but could indicate a QC issue during manufacturing. I don’t know who made mine, since I can’t read Chinese, but similar supplies can be found on-line under the name Mega-Watt or other makes with the similar red lettering in the upper left-hand corner of the printed label.

One of the other things to keep in mind is that the terminals are exposed, a concern especially for the AC input terminals. I plan to mount mine in a 2U rack enclosure with Power-pole panel mounts, an AC switch and volt meter. That should address the electrocution any nosy cats who may exploring the shack.

Until next time, 73!
de N3QO
dit dit

I got some free time this weekend to sit down and finally get the shack in order. Long enough to get some photos shot.

View at Picasa Operator Station 2 – Heathkit 301/40117-Sep-2011 15:15, Apple iPhone 4, 2.8, 3.85mm, 0.067 sec, ISO 250	View at Picasa Operator Station 1 – Kenwood TS-480HX SDR17-Sep-2011 15:15, Apple iPhone 4, 2.8, 3.85mm, 0.067 sec, ISO 200	View at Picasa Antenna Patching, switching, UPS and 12V Power supply17-Sep-2011 15:16, Apple iPhone 4, 2.8, 3.85mm, 0.067 sec, ISO 640	View at Picasa Operator Station 3 – Planned VHF+/Satellite/Guest Position17-Sep-2011 15:17, Apple iPhone 4, 2.8, 3.85mm, 0.067 sec, ISO 1000
View at Picasa Amateur Radio Station – N3QO17-Sep-2011 15:18, Apple iPhone 4, 2.8, 3.85mm, 0.059 sec, ISO 500	View at Picasa Amateur Radio Station – N3QO17-Sep-2011 15:18, Apple iPhone 4, 2.8, 3.85mm, 0.059 sec, ISO 640	View at Picasa Antenna switching, patching and power distribution17-Sep-2011 15:19, Apple iPhone 4, 2.8, 3.85mm, 0.059 sec, ISO 1000	View at Picasa Antenna switching, patching and power distribution17-Sep-2011 15:19, Apple iPhone 4, 2.8, 3.85mm, 0.059 sec, ISO 1000
View at Picasa The newest addition, VHF/UHF/Satellite station.07-Oct-2011 07:40, Apple iPhone 4, 2.8, 3.85mm, 0.067 sec, ISO 640	View at Picasa VHF/UHF/Satellite station. Icom 910h, Yaesu 5500 rotor, MFJ 1278B TNC.07-Oct-2011 07:42, Apple iPhone 4, 2.8, 3.85mm, 0.067 sec, ISO 400	View at Picasa SatPC32 tracking the ISS just off the coast of Florida.07-Oct-2011 07:42, Apple iPhone 4, 2.8, 3.85mm, 0.067 sec, ISO 100

In the weeks leading up to the ARRL DX Phone contest this year, Eric, WG3J and I did some extensive antenna planning at his QTH in Maryland in preparation for the upcoming contest. One of this biggest concerns was the amount of coax coming into the station. During a contest last year, we encountered a ton of RF affecting computers and audio causing an RF burn or two. Fun times.

How to resolve this? Reduce your coax run length and quantity by using antenna switches.

I reviewed a number of designs online and ended up designing my own, 2 position antenna switch which injects 12VDC onto the coax, so we didn’t require additional long lengths of control wire which could end up resonating RF.

View at Picasa Control board REV114-Feb-2011 22:47, EASTMAN KODAK COMPANY KODAK Zi8 Pocket Video Camera, 2.8, 6.34mm, 0.033 sec, ISO 111	View at Picasa Control board REV114-Feb-2011 22:47, EASTMAN KODAK COMPANY KODAK Zi8 Pocket Video Camera, 2.8, 6.34mm, 0.033 sec, ISO 131	View at Picasa Relay switch board. REV112-Feb-2011 02:25, EASTMAN KODAK COMPANY KODAK Zi8 Pocket Video Camera, 2.8, 6.34mm, 0.033 sec, ISO 107	View at Picasa Relay switch board. REV112-Feb-2011 02:25, EASTMAN KODAK COMPANY KODAK Zi8 Pocket Video Camera, 2.8, 6.34mm, 0.017 sec, ISO 134
View at Picasa Relay switch board. REV112-Feb-2011 02:25, EASTMAN KODAK COMPANY KODAK Zi8 Pocket Video Camera, 2.8, 6.34mm, 0.033 sec, ISO 80	View at Picasa Relay board with components. 10KW relay.14-Feb-2011 22:50, EASTMAN KODAK COMPANY KODAK Zi8 Pocket Video Camera, 2.8, 6.34mm, 0.033 sec, ISO 457	View at Picasa Relay board with components. 10KW relay.14-Feb-2011 22:50, EASTMAN KODAK COMPANY KODAK Zi8 Pocket Video Camera, 2.8, 6.34mm, 0.033 sec, ISO 483	View at Picasa Relay board with components installed. 5kW relay.01-Mar-2011 00:30, EASTMAN KODAK COMPANY KODAK Zi8 Pocket Video Camera, 2.8, 6.34mm, 0.033 sec, ISO 355
View at Picasa Relay board with components installed. 5kW relay.01-Mar-2011 00:30, EASTMAN KODAK COMPANY KODAK Zi8 Pocket Video Camera, 2.8, 6.34mm, 0.033 sec, ISO 318	View at Picasa Relay board with components installed. 5kW relay.01-Mar-2011 00:30, EASTMAN KODAK COMPANY KODAK Zi8 Pocket Video Camera, 2.8, 6.34mm, 0.033 sec, ISO 375	View at Picasa Control Panel front22-Feb-2011 22:20, EASTMAN KODAK COMPANY KODAK Zi8 Pocket Video Camera, 2.8, 6.34mm, 0.033 sec, ISO 800	View at Picasa Rear of control panel22-Feb-2011 22:23, EASTMAN KODAK COMPANY KODAK Zi8 Pocket Video Camera, 2.8, 6.34mm, 0.033 sec, ISO 613
View at Picasa Control board under test15-Feb-2011 20:56, EASTMAN KODAK COMPANY KODAK Zi8 Pocket Video Camera, 2.8, 6.34mm, 0.033 sec, ISO 244	View at Picasa 2 position DPDT rotary switch15-Feb-2011 20:56, EASTMAN KODAK COMPANY KODAK Zi8 Pocket Video Camera, 2.8, 6.34mm, 0.033 sec, ISO 188	View at Picasa Control board mounted25-Feb-2011 00:21, EASTMAN KODAK COMPANY KODAK Zi8 Pocket Video Camera, 2.8, 6.34mm, 0.008 sec, ISO 96	View at Picasa The makeshift assembly line in the shack.02-Mar-2011 08:58, EASTMAN KODAK COMPANY KODAK Zi8 Pocket Video Camera, 2.8, 6.34mm, 0.033 sec, ISO 357

For the next 3 weeks part of my station would be turned into an assembly line, etching circuit boards, fabricating cases, etc.

A week before the contest, Eric and I put the switches through their paces by dumping 2.5kW at 100% duty cycle for about 10-20 seconds. This would help us assure that they would hold up to the contest pace.

I ended up building five switches, 2 rated at 10kW and 3 rated at 5kW. I’m happy to report success with the design with no smoke emissions. One thing we did find was a high SWR at 15m and above, which I believe I have a fix, that needs future testing.

I’m not sure if I had previously posted about my acquisition of a Yaesu FT-847 or not, but in case I didn’t…

Back in September/October 2010 timeframe, I was looking to start working satellites after making contact with the International Space Station (ISS) from the car. I would end up buying a Yaesu 5400B az/el rotor, Tracking system, M2 2m circular polarized antenna and sell my Icom 746 for a Yaesu FT-847. I was set, or so I thought.

I would go on to burn out the motor twice on the 5400B rotor, with the already $1200 investment I had in the project, I would need to add an additional $900 on a 440 circular polarized antenna, and pre-amps for both. Needless to say what’s left was the 847, 2m antenna and tracking system, which most likely would go on ebay.

Recently I started getting back into digital modes, RTTY, PSK and CW and found that the 847 was quite sloppy on the receive side when trying to get selective on the station you are trying to work. With some research, I found the 847 itself had a 2.7k receive filter which was used on both SSB and CW. Quite wide for work below 170hz wide and nearby stations would end up desensing the receive causing the intended station to merely disappear.

What to do? Add filters of course! I opted to go with a different radio instead, and I’ll tell you why.

I’ve read a number of reviews about filter options for the radio including this one, which gave me hope of increasing the receive performance of the 847, although there is a fairly major flaw with the way Yaesu designed this rig. The filter that is already in place is a 2.7k and it is on full time. If I were to replace that with a 2.1 or 1.8, that would be fine for SSB phone work. Same thing with CW, drop a 250hz INRAD in the second slot and CW performance would most likely be spectacular. But what about PSK and RTTY? Both as SSB modes. Unlike the 746, there is no menu setting that I can change that would use a CW filter for SSB digital modes.

If I were to then replace the 2.7k filter with a 250hz filter for use on RTTY or PSK, the radio would then be useless for SSB Phone, because that filter would be on full time. Not exactly flexible in that respect.

So the thought was to replace this rig with a Kenwood TS-480HX and have it serve in the shack on a temporary basis, until I acquire a Flex 3000. The 480 would then go in the mobile in place of the 706 which came into the shack on the YL’s desk during the last PA QSO party.
[flgallery id=11 /]

First off, HNY or Happy New Year for those not sporting digital modes on HF.

Any New Year’s resolutions? At first I didn’t think I had but I guess mine would be the following:

-Actually learn code (CW) besides, CQ DE N3QO, 5NN and TU. A future post…
-Not spend as much money on the hobby as I have in last 2 years, although a Flex 3000 is in works.
-Timonium Hamfest, Timonium, MD.
-Dayton Hamvention. Enough said.
-Sussex Hamfest, I missed this one in 2010 because of work on-call.
-The 2011 antenna projects. See next post.
-..and finally, operate more, build less.

Writing the last post (year in review), I realized I did more station building than actual operation. I’m hoping we have better sunspot performance this year, but now I’m poised to hunker down and start working some DX.

As I’m thinking about what to write about 2011, I’m realizing that 2010 was a pretty kick ass year in the hobby for me and I’m starting to realize I’ve done too much. Here’s a summary.

In February I was introduced to 160m and found a great group located in the PA/NJ/DE/MD area who are on 1900khz every night at 8pm. I would finally get to meet them face to face at the Timonium Hamfest in Maryland which would start an every other Saturday tradition of breakfast in Delaware with the guys.

The hexbeam I built back in the previous October (2009) survived the 2ft of snow we saw in March. I would find myself being invited to operate the ARRL DX contest at NE3F’s, which is always fun but also quite an endurance run. I also started operating HF mobile and ended up working VK7ZE on our way to our club station with 100w in a screwdriver antenna on 20m. He was working the states long-path, some 14k miles.

Early in April, I decided to try a 3 element Mosley TA-33 tribander and ended up selling my Hexbeam to Dave (K3GMT). Also in April, I went QRO with a Dentron Clipperton which would be a requirement for 160m in the summer. 1200watts with a set of 4 572B’s. The transformer makes a menacing growl when it’s cranked on 40m, truely a welcomed addition to the shack.

Early in May, Jon (N3INJ) called to tell me 6m was open, of which I didn’t have an antenna for. Within about 45 minutes, I had a 6m delta loop up in the air and started making first 6m contacts. Later that month Laurie and I made it to Dayton. This was our first and plan to make it a yearly event.

I started off the month of June by rotating the polarity of my 2m cubical quad to horizontal and start working 2m sideband. So far it’s been slow, but my furthest stations I’ve worked was Pittsburgh and Connecticut, but the ARRL VHF contest was a blast!

The 1900 guys and I would end up doing a Field Day Expedition to Assateague Island in Maryland. It took a fair bit of planning, governmental politics and a little bit of cash, but we pulled it off. We also pulled off toasting an Alpha amplifier and an Icom 7000. But we all made it out alive with a new experience under our belts and I experienced a pileup the night before on PSK from the beach.

Early in July, I installed the trapped 40/80/160 antenna and start getting S9+40-50 signal reports on 160m, something no G5RV would do. Later that month I would end up in,out and then back in the hospital for a perforated appendix, which made for good rest time for DX at home, but no HT’s in the hospital. I also missed out on IoTA weekend, bummer.

In August I started playing around with satellites and sold the Icom 746 and purchased a Yaesu 847. Just as quickly as I got into this mode, I was out of it, but I walked away with a QSO with Commander Doug Wheelock aboard the ISS while we were mobile.

September my HF configuration came full circle. I ended swapping out the Mosley for my previously rebuilt hexbeam. Luckily for me, K3GMT’s plans for it didn’t work out, and I have my creation back on the roof and working DX like a mad man. At the same time we relocated the 2 meter antennas to a newly installed guyed mast just behind the garage.

October 1st I would wake to find my shack in the basement flooded due to a large rainfall. A normally quiet sump pump would awaken in the night, but a tripped GFI breaker caused it to stop and leave me with a foot of water. No ham equipment was harmed, but the shack ended up being relocated to the dining room. Luckily for me I have a loving, understanding and licensed (general) YL. Speaking of which She and I worked the PA QSO party, but she has not yet given up my Icom 706. I don’t have the heart to take it back, and not that I need it, but it gives me an excuse to buy another rig.

The last quarter of 2010 has been fairly quiet. I’ve been voted into the board for my radio club, working towards DXCC, working more CW and playing around with APRS.

Laurie and I are both looking forward to a prosperous 2011, with me hopefully working HF mobile once again. Hi Hi.

Recently I was researching computer rotor interfaces and happened across the website of Idiom Press, who makes a product called Rotor Card. While browsing their site I found that they sell an audio filtering kit called the SCAF-1. The filter was designed for older radios without DSP (digital signal processing) or additional filtering to make those heavy QRM filled QSO’s more tolerable. My Icom-746 is one of the first generation radios with DSP and I also have 2 additional filters installed (350hz and 1900hz), but I wanted a little more flexibility in my filtering options.

On my particular rig when I enable noise reduction (NR) I tend to get a fair amount of ringing in the filter, an artifact of the older DSP technology. In addition to that Icom’s PBT (PassBand Tuning) only goes so far. My 1900hz filter in the rig could clean up the IF stage of the receiver, but I needed something more to make QRM filled receive audio more tolerable. I also started thinking about the possibilities with RTTY and PSK31.

After listening to Idiom Press’ audio samples on SSB phone and CW, I was sold. I decided to go with the kit form to save a few bucks and experience the challenge of building a kit. Since my last kit (D-Star hotspot) was a success, I was up for the challenge. $90 and 3 days later the kit arrived.

The included instructions were very clear and very consise and the kit assembled exactly like they had stated. One issue I encountered was wrong resistor (miscount). Where I required a 3rd 10k ohm, I had a 100 ohm. No biggie, nothing that I can’t get at my local Radio Shack. Thankfully mine still sells common electronic components. The other issue was trying to figure out the pin ID on the DPDT switch. Unfortunately I soldered mine backwards and the switch is keyed to install in only one direction. All this really means is the UP position is OFF and DOWN is ON. Again, no big deal.

I had most of the kit assembled in the course of 3 hours while I was carrying participating in my usual 8PM net on 1900khz. Today I was able to pickup the remaining resistors and also some audio cables to interface it into my rig setup. I decided to place it between the AF output of the radio (accessory audio output) and the rig audio input of my Rigblaster. This way I could utilize it for digital modes on the computer, which is a direct feed to my monitor speakers. The filter has 2 audio outputs, one for headphones and external speaker audio. The kit gives you the luxury of choosing which size jack 1/4 or 1/8 inch you wish for either function as well as if you want stereo or mono. Since it’s ham radio and the most audio bandwidth I’ll ever hear (from a properly tuned transmitter) is 6khz (on AM), I decided to go mono for both.

Upon powering up the filter for the first time, I was happy to hear the exact results I had heard on their website as well as nothing blowing up (reverse polarity electrolytic capacitors become missiles). The instructions call for you to adjust the internal potentiometer, but I had found the audio to be consistent with it set to the middle.

Check out the photos below and also take a look at the audio spectrum I had captured with the filter in line as well as out.

So far I’m happy with the results and look forward to using it during contests and busy digital waterfalls.

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After my Dayton post, I just realized that I haven’t posted about my recent addition to the shack, my Dentron Clipperton L amplifier. It outputs approximately 1200 watts PEP from 4 Svetlana 572B tubes. So far it’s been a blast and makes my nightly 8pm ragchew on 160m (1.9mhz) effortless. Here are the photos:

View at Picasa	View at Picasa	View at Picasa	View at Picasa	View at Picasa	View at Picasa
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I just had to do it… I had a spare D104 and an Icom microphone connector.

View at Picasa

Last night while on the 1900 Net, I heard that it was possible to run the Icom 746 with separate transmit and receive antennas. According to Sky’s Daughter’s FAQ it was possible to do this running split, setting VFO-A on Antenna 1 and VFO-B on Antenna 2. Unfortunately I have been unable to make the Antenna selection follow the VFO but I’m going to keep trying to figure it out. Links available below:

Sky’s Daughters 746 FAQ PDF Link
My local link to the 746 FAQ PDF