WB4IUY's Random Blog
Tuesday, December 4, 2012
We retuned all of the receive & transmit cavities, and found them all to be out of adjustment...some by quite a bit. They were last adjusted back in 2002. We changed the configuration of the cavities to improve isolation, and have an additional pass cavity on the receive and transmit ports. De-sense is gone, and all is well with that aspect of the repeater, now.
All 4 cooling fans were replaced. They run non-stop, and have turned many revolutions since the installation of this repeater at the Clayton site in 2002. All of the heat sinks are cleaned, and the repeater is running nice and cool.
A temporary repair had been made a while back with a jumper lead, and that was removed and hard wired to correct a control logic problem. There is one more similar issue, but I forgot my glasses and couldn't see the terminal that needed to be soldered :-)
Weak signal tests were made, and it is responding to signals that are right down in the noise, so we're pretty happy with that. A few programming changes were made, and that wrapped up the work for the day.
The "to-do" list is getting short now with only a few items left like: replacing a defective PL encoder board on the transmitter, repairing a control logic issue for the 2nd voice announcer module, and replacing a backup battery on the voice IDers.
Next, the work on the Clayton site begins...
The property owner now stores hay for 18 horses in the rear of the barn in the area where the repeater lives. The floor was at least 6" deep in hey stems and very finely ground chaf from hey. The upper & lower repeater cabinets were completely clogged with hay, chaf, and cobwebs/spiderwebs. The fine dust, which had some of us coughing and sneezing, was at least an inch deep inside of the repeater on some of the electronics to such a point that much of the wiring was completely hidden and all 5 cooling fans were seized up. Heat sinks on driver, power amp, voltage regulators, etc were clogged with the same stuff. I honestly don't know why the repeater had not blown up and/or caught fire. Additionally, the lower cabinet where the duplexers and other items live were in the same condition. It also seems that a dog had found an opening into the rear of the enclosure and has been using the lower section of the bottom cabinet as a toilet and was literally covered in copious amounts of doggie poo.
We pulled out all of the repeater releated equipment, loaded it up, and hauled it off for cleaning and re-installation. It has now been cleaned pretty well, reconnected at a clean site, and is receiving some much needed repairs while keeping it on the air as best as possible. It is suffering from some desense issues at the moment, but more work is planned for Saturday. It should be up and running well in time for the Tuesday night net. We'll also be making some controller and other changes that should improve coverage and functionality.
Tower: We discovered several serious antenna related issues. The tree that had grown up into the tower has been trimmed and the most pressing parts cut away from the tower. There are still a couple of limbs to remove, and I'll get to that shortly. The more significant issue is where someone has run into the southwest elevated guy point and sheared off the backup restraint that ties it to the primary anchors. This allowed the elevated guy point to pull towards the tower, loosen the 3 lower SW guy wires, and allow the bottom 1/3 of the tower to slowly curve towards the northeast. I've got to repair that right away, before an ice storm and tower loading causes the tower to fall. There are also a few ice splits in the lower section that have to be repaired.
Antenna: Examination of the top mounted 4 bay dipole array that has served 147.39 for about 20 years revealed more problems... One of the top folded dipoles has loosened and turned towards the mast about 90 degrees. Another of the folded dipole loops is completely missing and no where to be found on the property. The link antenna has blown around and the multiband vertical is twisted in a pretty bad band. Again, I'm amazed that the system was still working as well as it was.
Monday, November 26, 2012
After a bit of experimentation, I discovered the FV-101DM can be interfaced to the FT-901DM with a little work, and retain most of the functionality of the FV-101DM's original design. Here's what has to be done:
1- A jumper must be installed from pin 7 of port A to pin 1 of port B on the VFO.
2- The 6-pin cable supplied with the FV-101DM only utilizes 3 wires (with no shielded circuits for the VFO output), as it intends for the VFO communications to the 101ZD to be via VFO port A. For this reason, a new cable with 6-pin connectors must be assembled to connect from the FT-901DM to the FV-101DM VFO port B. Wire the cable, pin to pin (i.e. Pin 1 to pin 1, pin 2 t pin 2, etc). Use a piece of small coaxial cable with the center conductor connecting pin 1 to pin 1, and the shield connecting pin 2 to pin 2. Standard unshielded wire is fine for the other pins.
3- Assemble a power cord to plug into port A on the VFO, to supply an external 12 vdc source to pin 1. Include a fuse link at 250ma to protect the circuit in the event of a problem. Connect the negative of the 12 vdc source to the cabinet of the VFO (there is no ground connection in the socket for port A on the VFO).
That's it! Mine is working great, and has all functionality except the VFO memories can not be programmed from the FT-901DM, but can be programmed from the VFO just fine. This is because there is no feedback path from the FT-901's internal VFO to the FV-101DM VFO like there is with the FT-101ZD.
The FV-101 is a good cosmetic match, and works well with the 901 after these mods. Below is a pic of the reassembled VFO as paired up with my FT-901.
Saturday, October 6, 2012
I've pasted a pic of my band scope in this blog, so you can see. Normally (during the summer months), noise is about 1/3 the way up the band scope and distant signals are almost impossible to hear. During the fall, winter, and spring, noise is lower and DX is abundant.
The first 160m DX of the season for me, was SV3RF on 1.81852 in Greece via 180m inverted V @ 100'. He was 559 in NC. The next morning I worked VK6GX in Western Australia on 1.8215 CW at 11:20z (7:20am est). Same 100w w/Inverted-V. Yesterday, I worked VE1ZZ on 160m CW this morning around 6am. Not great DX, but it was the only thing on the bad outside of the USA in earshot and the band was quiet.
So, put up an antenna for the winter and get on 160. You'll be surprised what awaits you on the "Magic Band"!
Monday, July 30, 2012
HERE on my personal hamfest page.
In years gone by I've parted out estate sales, loads of government radio gear, TV shop inventory I'd bought, along with various pieces of radio equipment I had repaired and wanted to sell. I found it much easier and more relaxing than trying to drag all that stuff to hamfests and less trouble than trying to manage a bunch of eBay listings.
I have many hundreds of tubes, all of which have been tested on my Hickok mutual conductance tester. They are a mix of NOS inventory, pulls, etc. I originally bought all of these to supply my own restoration needs for my boat anchor collection, but it got way out of control :-) You can take a peek at some of them HERE .
I'm always looking to improve my work bench on the cheap, so I'm constantly picking up used test equipment to restore. As a result, I also have a bunch of pieces of test gear in various stages of restoration. Some good, some not so good, some just for parts. You can see some of it HERE
I'm also always looking for that 'next piece' for my boat anchor collection. I list the items I'm looking for on my hamfest page as well. The inventory that is for sale is constantly changing, so keep an eye on the site and let me know if you see something you need. if so, drop me a note at firstname.lastname@example.org .
Sunday, July 15, 2012
Wednesday, July 4, 2012
On 6/1, I was enjoying working some DX on a Sunday afternoon, when a storm came up. I disconnected everything and shut down. The AC power, cable, and even the local cell phone tower was knocked out.
We have a 'whole house' generator, so I switched over to the it and got the house back up and running, A/C and all. The storm passed, but power didn't come back on. I reconnected my antennas, changed my dx spotting from telnet to TNC, and reconnected to the cluster via packet radio.
Here's a pics of the logging program being switched to TNC mode in the DX Cluster interface and connecting to the packet radio DX Cluster...and the spots were flowing again! Even with the power out and no internet at home, I was DXing and posting spots. The outage even took out my cell phone here, but my old technology still works great!
Monday, April 23, 2012
After looking at my old Yaesu FT-901 in Studio "A" with a failed transmitter for several months, I decided to dig into it this past rainy Sunday and see what had gone wrong with it. I checked the usual things... the 6146's and 12BY7 tubes, bias, operating voltages in the RF cage, etc. All was normal. It was actually producing about 100mw, and all was loading up OK, she just wasn't pulling any plate current above idle, as if there was no drive. I broke out the scope and started poking around a little, and discovered the TX output from the RF board to be waaayyyyyy down. After some voltage drop checks, it looked as if one of the 3SK40L's N-Channel mosfets had failed.
I scrounged around in my Yaesu spare (junk) parts box, and found an RF board from a later model. Mine used the PB-1702, and I had a PB-2154A from a later (newer) model. You can see the two boards compared above, and the component layout (and overall design) to be very different. I compared the pinout on the edge connector between the two in my shop manual, and that seemed to be the same. The old board used two FETs in the mixer, the newer boards uses a diode ring mixer. I started to pull a FET from the new board, but a bit more reading on foxtango.org suggested the newer board would work and was an IMD improvement.
On the left, you can see the new version RF board plugged in for a test, with the red, yellow, and green cables plugged into the top. I plugged the new board in, flipped the switch for a smoke test, and she came alive with full output. Yipee!! All is well, and my old FT-901DE is back on the air with a newer version RF board to boot. Ya gotta love these old rigs for ease of service. My rig is one of the early serial #'s, produced sometime around 1978. Despite it's age, it was one of Yaesu's flagship contest rigs of the day, and still preforms pretty darn good today.
Sunday, March 18, 2012
The Russian DX Contest is running this weekend. The neat thing about this contest is, you can work anyone, anywhere...not just Russian stations. So, it makes the bands a bit more lively and enjoyable. I'm up at 12:45am playing around on 20m, and surprisingly enough...the band is open from VK to PY to XF, etc. Very pleasant conditions to work with 100w. You can find more about this contest at:
Saturday, March 3, 2012
I'm finally getting a little radio time again...been working non-stop for the last several weeks. I'm enjoying a little of the ARRL SSB International DX Contest this weekend. It's a great way to pick up a few new countries, make a bunch of contacts, and give the serious contesters out there some points.
You can find more info on this at hornucopia.com and at arrl.org . When I'm on, you can see my operations from "Studio A & B" on some of my cams at WB4IUY Shack Cams
Hope to see you on the air!