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Re: TX500: A Five-day Rollercoaster
Re individual incident...maybe not. I managed to blow the audio amplifier chip in my TX-500 a few weeks ago just before the North American QSO Party SSB Contest operating from a portable location (Atlantic Beach, NC).? Lab599 Service USA quickly analyzed and repaired the TX-500. Background: I had my TX-500 mounted to the side of an Elecraft KXPA100 with an external speaker and Heil HC4 mic element attached through the stock mic/speaker/PTT adapter. I also had a homemade adapter cable connected to the REM/DATA port providing PTT out to the KXPA100.? This connector also had wiring to PTT in, in which I had connected to a footswitch.? Although not being used, I had wires for the Audio In and Out.? All of the wires to the REM/DATA port were about 3 ft long and unshielded.? The 8 ft long footswitch cable was connected to the 3 ft wires via two 2 ft long alligator-clip leads.? The external speaker (MFJ-281) had a 4 ft shielded cable.? All of these wires were laying around loosely on the operating table.? The antenna was a PAR EF-QUAD in horizontal orientation about 30 ft from the operating position and was connected through 75 ft of RG8X.? Everything was working well, I made several POTA contacts on 40M that Saturday morning running around 50 watts from the KXPA100 (TX-500 Power at 50%).? BTW, For those of us phone guys who don't carry a CW key everywhere we go, we use the "TUNE" feature, or some combination of buttons, of most other radios to generate a CW tone to adjust actual power out and check SWR.? There is no "TUNE" feature discussed in the manual.? After a reading of the manual I found the Menu Feature #24 Type Tone which discussed exactly what I needed.? But there was no reference to where to go in the manual for instructions on how to initiate the "TONE".? After doing a word search of the pdf file, I found the instructions in the Receive Settings section (last item) of the manual; not exactly where I was expecting transmitting details. Event:? I increased the TX-500 Power to 75% and proceeded to check power output of the KXPA100.? On 40M I had around 90W, on 20M it was 100W and on 15M it went to 100W and a loud POP.? Not having enough time before the contest start to troubleshoot the issue, I packed up the TX-500/KXPA100 and all the wires.? I proceeded to operate the contest with my Elecraft K3/100. Post Event:? After arriving back home I reconnected everything on the kitchen table.? I determined that the TX-500 receiver and transmitter were still working OK, and the audio out from the REM/DATA port was OK.? The only problem was no speaker audio from the MIC/SP port.? I packed the TX-500 and sent it to Lab599 Service USA. Thoughts:? I know this is a new radio design and there may be unknown issues that develope over the early usage of the units.? So, now with possibly two audio amplifier failures, is this an issue or just two isolated instances?? I don't know.? Was my setup with all of the unshielded and long wires the path for RF from the nearby antenna the real problem?? If so, why didn't the event also eliminate the audio out from the REM/DATA port?? Was mounting it so close to the KXPA100 the problem?? I bought the TX-500 because of its unique packaging and features and plan to keep it.? I still have other radios to use if the TX-500 is not suitable for high RF environments.? It is still a great little rig for portable outdoor usage.? Since I left early for the beach, I was unable to use the TX-500 in this past weekend's Winter Field Day event.? My next opportunity to use the TX-500 will be at the end of the month during the CQWW 160 SSB Contest from the beach house.? When the weather gets warmer, I really will use the TX-500 alone in some outdoor setups. Sorry for all of the details above, but wanted to provide information that might be useful to others with a TX-500. I welcome any further thoughts or questions from others.? My next TX-500 project is an attachable battery pack. 73, Henry - K4TMC On Tue, Feb 2, 2021 at 8:07 PM Weishan Liao <weishan.liao@...> wrote: Some of you might have been seeing my posts on the Facebook group, but I think I'd shared my though on the transceiver here as well. |
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