I've been looking at migrating some of the work I've done on my ComboStar build to VHF/UHF including GSMK and Codec2. With 3D printed case, lithium battery, STM32F405, DRA818V/U, and a nice OLED screen I think its possible to build a DIY 1 Watt radio that support analog, FSK (APRS), and Codec2 GSMK. I already have several working STM32 projects with successfully generating various modulations including GMSK, POCSAG and AFSK. My first step is to play with the DRV818V module and see how difficult it is to implement. From the datasheet I've included a low pass filter in this prototype which I should be able to prototype with my existing STM project board.
I've taken on yet another TS-430 and ran into an issue with whats coming off the PLL board. I traded a TS-430 I had purchased as non-working which I repaired/tuned for a unit in very nice shape cosmetically but not working. Another HAM back on the air, but now I have another TS-430 to figure out. I suspect this may be an issue with VCO signals coming to the PLL but after spending several hours getting to this point, I've put the project down for a bit to work on my workshop. Hopefully someone on a list somewhere has seen this before and I'll hear back from someone by the next time I pick this project up.
I have a HP 8935 E6380A service monitor that had some pretty severe screen burn. After looking around for a replacement I wanted to see how hard it would be to adapt a current LCD to the 8935. Suprisingly it was fairly easy. I had a 10.5 inch display and after probing around a bit to see what signals/power were on the A1A1 connector (400 i think) I started playing with a FPGA dev board to convert signals to something I could see on the screen. It works but doesn't fill the entire screen and its not the right size hardware. Now that I have a PLAN B and I've found a 6.5"ish lcd I can readily buy cheap, I'll troll along with the burnt display till it fails or I can't stand it anymore. I'm hoping there is a lot of interest in this to other 8935 owners and its something I can justify doing in the near future.
Some things I played with while I had the 8935 apart and the 10.5" connected:
- Inversion to have some way of preventing screen burn.
- Adding some color (Changed boarder color, changed color of spectrum analyzer portions of the screen) This isn't something that can be done everywhere. If its simply which pixels get what color it's trivial.
- Added text to the parts of the screen not used going from 512x256 to 640x480. Could add ADC to show voltages etc as extra info.
-Centered screen and added border.
I recently discovered my B & K E200D would no longer modulate while working on a Kenwood TS-440AT. After getting inside the E200D nothing appeared to be unusual and I remember a site I had used before when searching for the switchcraft connector I needed to make a cable for this unit. http://www.freeinfostuff.com/E200D/E-200D.htm . After going thru the calibration procedure, everything was in calibration with the exception of the modulation level which once I adjusted the level the modulation meter was back in action. Easy quick fix and now I know that the unit is calibrated.
I recently purchased this Tempo 2020 HF radio to rebuild. I plan to start this project after the TS-430S is finished.
Yahoo Tempo Group (Very Useful) http://groups.yahoo.com/group/TEMPO_2020/
KX4OM Tempo 2020 Repair pages http://www.kx4om.com/TechSolutions/Tempo2020_repairs/2020.html
I've had several email's about some of my test gear in recent weeks and one item of interest from many was the cable used on my B&K E-200D Signal Generator. I used a premade 50 ohm BNC cable and attached a 2501F connector. So if you need these connectors they can be found numerous places. Search for 2501F, vintage mic connector etc to locate the connector. I prefer when possible to keep my gear original in case I sell the unit for an upgrade and the cost of the connectors is very small. I was able to purchase two for less than $12 including shipping. On is a BNC adapter and I used the other for a 50ohm gator clip style cable. Switchcraft is the manufacture of the connectors I used.
The datasheet is below.
I made it a bit deeper into the 430S this weekend. While checking the alignment, it was clear there was an issue with the RIT. It didn't seem to work and I wasn't seeing what I should have been at D5. After looking around a bit on the board I found that VR3 was working sometimes and sometimes not depending on what mood it was in. After replacing VR3 I wasn't getting a proper RIT 9mhz signal but everything is more consistent now. I noticed the dreaded glue around the 9mhz osc which concerns me and I'm very suspicious of that area. When I have time next step is to remove all the glue from that area and try and determine if that has something to do with RIT not functioning.
07/24/2011 After deeper inspection of the glue area it became very apparent that X6 (9mhz) was no longer connected to the board. The leads had broken off right at the PCB. I've spent some time trying to source a replacement. Hopefully I'll locate one soon.
08/01/2010 The control board now checks out with the 9mhz replacement. On to the PLL board.
I've been doing some clean up on the filter unit for the Kenwood TS-430S HF radio. Some bands were not working and the filter unit was suspect. I had already tried the prescribed 12 V DC current treatment without any changes on the bands that weren't working. I noticed several bad joints and manually disassembled each relay and checked its operation. At least two of them were not making good connections and required cleaning with some contact cleaner and a dollar bill. After this cleaning they seem to be working. I also noticed several bad solder joints. Here is some photos of the board.
After doing some initial testing on the Kenwood TS-430S project cleaning up the IF board issues I had been getting 100 watts on some of the bands. Suddenly last night during a test I noticed the radio would begin clicking and resetting. After a bit of head scratching and doublechecking power going into the radio I finally traced it down. The molex connector at the rear wasn't making a good connection. I used some needle nose pliers and some deoxit and solved the problem. A quick fix to a problem is always good.
07/14/2011 - After removing the IF board from the TS-430 I could see some issues right off hand. The top site of the board was realitivly clean although I noticed some excess thermal compound on the regulators which gave me a hint that this IF board had been repaired at some point. Getting it out I could see lots of oxidation, burn traces at one of the regulators and at least one connect that had ripped the traces from the board. Tonight I cleaned up much of the board tested all the diodes on the rear of the board, and repaired the 5V traces. At this point the radio seems to work but I don't have very good recieve and it still only transmits on some bands. On the bands it does transmit on it does full output which is a good sign. I'll be working on the IF board for the next few days as its in bad shape on the rear side.
07/18/2011 - Well thus far, I have replaced the traces on the 5V regulator with jumpers as the eyelets were missing and that area of the board wasn't in very good shape. I also located a burnt or gouged trace which will need repair. A missing eyelet was found on Connector 10 and I ended up glueing the connector to the board and replacing the trace with a wire. After looking at the board from the top I've noticed several missing caps. I expect someone has tried to repair this board and during checking cold solder joints they may of pushed the caps off the board without noticing.
07/19/2011 The gouged trace has been repaired. Now the IF section seems to be working at least a stage or two away from the audio section. I ended up with a TX issue which was a bad connection at the molex connector which slowed progress on the IF board issues.