Charles Socci - Information Technology

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Just a quick post. We’ve got some new antennas up.

Here’s the new Guanella type balun I wound:

After experimenting with an 80m half wave dipole, I found a shorter 31m length was a better performer on most bands for me with 13 meters of 600 ohm open wire feeders. The dipole is about 13m high. It is similar in length to a G5RV, however the open wire feed has a characteristic impedance of about 600 ohms. The balun sits outside and feeds a tuner in the shack via approximately 8 feet of coax.

I also built a quarter wave vertical for 40m and will be making a relay controlled matching network for 30m soon. There are about 40 radials on the ground presently with more planned.

I had a computer headset with a boom mic that no longer worked. I think the small wires inside the molded plugs had broken.

I had always been impressed with the audio quality of these relatively cheap Logitech headphones and microphone. The mic naturally has a strong mid-range peak that I think lends itself very well to HF work and getting heard in a pile-up. But that’s just my theory.

I had been successful wiring up my Kenwood MC-50, using pinouts I found on the Internet. The mic jack for the FT-857 is an RJ-45. The pinout for the FT-857 is as follows:

1 – FAST Scan
2 – Ground
3 – PTT
4 – MIC +
5 – MIC Gnd
6 – +5 Volts DC
7 – Up
8 – Down

The tricky part is figuring out which pin is pin1!  I used an old CAT 5 network cable, and I used the following pins: 2, 3, 4, 5 and 6. On my cable, these were white/brown, green, white/blue, blue, and white/green. Color codes can vary, so double check.  If looking at the microphone jack directly,  pin 1 is all the way to the right.

The following site was very helpful to me in getting pin outs for Kenwood and Yaesu: G4WPW Microphone Connections

Here’s what I ended up doing and after a few HF contacts, and some on the local repeaters I’m convinced it works pretty well.

Headset

One leg of the “stealthy doublet” (see previous post) blew down. We decided to take a new approach to launching our antenna wires into the trees.

We purchased some regulation baseballs and a roll of nylon cord (similar to mason’s line). We used some previously purchased 4 ounce fishing weights, packing tape, and taped a weight and length of cord onto each baseball. This was tied to the loop on the end of each insulated wire. The 9 ounce baseball/weight combo was then tossed into the tree line where it is doing an excellent job holding our wire antenna in place…

I got my first ham radio license years ago at age twelve. I was in the seventh grade and we lived in a semi-rural area and private house. I had 3 element yagis on the roof for 10 and 15 as well as a trap dipole for the other bands. My immersion in ham radio occurred during the height of sun spot cycle number 21 and it was fun!

At 44 years old I’ve jumped back into my radio hobby with gusto: But I now find myself living in northern Manhattan in New York City, with no yard, in a second floor apartment that faces an inner courtyard on one side, and masses of urban infrastructure on the other. I can hit the local repeaters with my HT, and even some not so local ones with a 2meter/70cm quad that I built – but how boring is that? I like HF. I like a challenge and the thrill of overcoming a problem with a workable solution.

I started with an indoor doublet. A doublet is another word for dipole, but usually refers to a dipole that is fed with balanced feed line and tuned to operate on the band desired. I got about 70 feet of 23 gauge magnet wire string in a z-shape from one end of the apartment to the other and fed it with TV twinlead. Needless to say, the results were not stellar… buried inside brick and morter, surrounded by many other structures and in the middle of an RF nightmare – from the plasma TV, to my home computer network, and anything else capable to creating interference. I managed to work one or two stations via ground wave but it was nearly useless.

After looking around various ham radio websites, I discovered the Jackite fiberglass pole, which is 31′ long and can be purchased for under $70 online (try E-Bay). It telescopes down to 4 feet and extends out to something resembling an oversize fishing pole, 31 feet long. I got to thinking – there are trees in back of our apartment building in an alley between our building and a small public green space opposite my fire escape. Our neighborhood is in one of the highest elevations on Manhattan – my QTH is around 200-220 feet above the Hudson River. I realized I could get on my fire escape (another 20 feet up) and push an antenna up into the trees.

I built a fan dipole with legs cut for 40, 20 and 10 meters – planning to use it on 15 meters as well which is the third multiple of 40 meters in wavelength. I fastened the vertex outside my bedroom window and pushed the ends of the 40 meter legs up into the trees (with porcelain dog-bone insulators on the end for weight). It was much harder to get the 20 and 10 meter legs in a good position due to their short size, and the distance away of the trees. None the less, performance increased and I worked a bunch of new stations on 40 and 20 using SSB and PSK31.

I decided that the best idea would be to get a simple doublet up in the tree line that sits at around 50 feet above the ground. It would be far easier to manage two legs than six. I could tune it with high efficiency on all bands if I fed it with balanced line. The only drawback was managing the balanced line into my apartment on the second floor – and figuring out how to pull this off since the roof is off limits to tenants – and I doubt my ability to convince the superintendent that my radio obsession is important enough for him to let me up there to do my thing.

Roof tops and trees

I managed to get my antenna in place – although the exact method will have to remain up to your imagination. It is in a V configuration that has a vertex at nearly 70 feet and droops down to about 40 feet. All in all the 102′ doublet is between 40 and 70 feet off the ground. Its not a perfect installation, but I kept it clear of most metal, power, networking, and phone cables. It makes the occasional brush, but avoids extended runs parallel to any one line. One could make a similar doublet with plain zip cord as a feedline. Old timers used to do this frequently. There’s always a solution: its a matter of making the most of (or minimizing) compromises.

The real test was getting it on the air – and it was like having a new radio. The noise level was down. Signals could be heard, and I was immediately able to work stations from Mexico to Wisconsin and South Carolina to Kentucky with S9 signal reports. After weeks of no responses to ‘CQ’, suddenly people were responding!

Success! and if the forces of nature and neighbors allow me to keep my antennas in the trees for awhile I’ll be most happy.

Took the exam tonight down at Columbia University tonight and passed my exam.

Hurray! Time to start working those sweet parts of 20 and 40 meters, and get one of those fancy call signs!

I picked up an 80′s vintage Kenwood TS-530s on EBay. The rig was in great shape but the output power was very low. After searching on Google for information about my new radio, I found Ken, K4EAA’s *excellent* webpage on Kenwood hybrids. Ken also refurbishes Kenwood radios professionally and also sells the parts needed to do-it-yourself.

After reading Ken’s pages and shooting him a quick email I realized that I needed to replace the cathode and screen resistors in my TS-530s. Never having owned a Kenwood, and having only some limited experience digging in under the hood of a Heathkit HW-101 I was a little bit afraid. But curiosity prevailed. I was also able to download a service manual for the radio here. I could not find schematics of the 530, but I did find schematics on Ken’s site of the 830 which is similar if not identical in terms of the final board and the rectifier board, which are the two boards where we find the screen resistors and cathode resistors.

I ordered the parts from Ken which arrived in a few days, and then I set out to make my repairs.

Ken told me the cathode resistors would be on the final board, as well as two 100 ohm screen resistors. The remaining screen resistor is a 470 ohm on the rectifier board. It took me a while to figure out what was where, but it was fairly easy to identify the four 20 ohm cathode resistors and two 100 ohm screen resistors on the final board. The 470 ohm screen resistor on the rectifier board sits right in the middle and you can’t miss it.

A SAFETY note: Danger!! High Voltage!!
“Hybrid rigs such as Kenwood TS-520-820-530-830
have high voltages that can be as high as 800 volts in the power
supply and final section. These voltages can kill you!
This is actually true of any rig with tube finals. Keep this in mind
when working inside these rigs.
After these rigs are turned off, these voltages remain
in capacitors and can still harm or kill you. Most of
these rigs have bleeder resistors that are SUPPOSED to
discharge these capacitors in a short time after the
power is off. These are usually of values in the tens or
hundreds of thousand ohms and are usually placed
across the capacitor to drain it. Are these working
right in your rig? Would you bet your life on it? I
wouldn’t.
As a safety precaution, one should ALWAYS discharge
these voltages manually before touching anything in
the rig. To do this, unplug the rig and let it set for 3 or
4 minutes. If the bleeder resistors are working, this
SHOULD discharge most of the charge. Then using a
screwdriver or a good clip lead, short the
top of the plate choke, to ground. The top of the plate
choke is the place that feeds the two tube caps by way
of parasitic chokes. Discharge the top of the plate choke. The top
of the plate choke is the place that feeds the two tube
caps by way of parasitic chokes. There is enough
voltage stored up in these capacitors to create a high
enough current to stop you heart.”

I removed the top and bottom covers of the case. I disassembled the protective cage around the finals. *make sure you short the I removed the finals, making sure to note which final came from which socket. (I don’t know if this is necessary, but its probably a good idea to not mix them up and alter the adjustment of your radio). I then unscrewed the final board from the bottom and was able to pull it out just enough to remove the old resistors and replace them with the new ones. I did the same for the one resistor on the rectifier board. I then put it all back together and proceeded to enjoy my repaired rig.

See the following illustrations (you can click on any image for a large version):

1) This is the bottom of the radio after removing the case. The final board is in the upper left hand corner and the rectifier board is just to the right.

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2)Here is a closeup of the final and rectifier boards.

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3) Removing the plate caps and pulling out the 6146b finals.

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4) The final board of the Kenwood TS-530s showing the newly replaced resistors. Note the location of cathode and screen resistors.

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5) The rectifier board showing the single 470 ohm resistor.