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Showing posts from May, 2020

Tecsun PL-606 External Ferrite Loopstick Mods

As the PL-606 has the same antenna jack as the PL-310ET I though I'd take a look and see how easy it would be to carry out the modification. Actually more straightforward on this set. Unfortunately, when I removed the rear cover, I found the internal ferrite bar in two pieces. I've repaired this using superglue which has worked for me on other ferrite rods. The end results on LW are as impressive as the 310. On MW, despite trying two different coils (500µH and 200µH), results at the lower end of the band showed an improvement but at the top end the performance appeared worser than the internal ferrite bar. Conclusion? Definately needs the mod for LW but quite adequate for MW.

9700kHz 0519UTC - RNZ Pacific (weak audio, noisy reception)

RNZ Pacific moved their 04:59 transmission from 11725kHz to 9700kHz on 18th May. Always difficult to copy from home, here is today's attempt on a quiet 31 meter band. The transmission disappeared abruptly at 0624.

13760kHz 15245kHz Voice of Korea - Another Diversity Reception Demo.

For some strange reason, VoK always lends itself to my diversity reception experiments, this time with the XHDATA D-808 and RADIWOW R-108, recorded on 29 th June 2019. Enjoy!

Roberts Sensitive Sangeans

A couple of Roberts branded Sangean sets that are both faulty, but still manage to bring in the DX. I already have the R816 (ATS-909) so my curiosity got the better of me to see how the lesser models from that era perform. Roberts R617 is the Sangean ATS-606, early version with a DISPLAY button. The later models have a FINE tune in this position instead which allows 1kHz tuning steps. This one runs OK for a while and then the PLL circuit will lock up. At present, proving elusive to find the cause. Roberts R809 is the Sangean ATS-808. This one came to me faulty as it's obviously suffered display damage. Also had a 1kHz tone present on all the LW/MW/SW signals. Applying an unmodulated test signal, the tone got louder as I increased the RF level! After testing some suspicious capacitors around the PLL circuitry and finding them to be OK, I found contamination in various places on the microprocessor/keypad board which I've cleaned up and it now works. Another parts donor ...

YouTube :: Radiwow R108m2

So while I've been carring out a trivial mod to improve the PL-310ET, YouTube user 66vds has done a great job of improving the Radiwow R-108 by removing the internal ferrite and modifying the external antenna connecotor to work on all ferequencies. Here are links to the details: Internal photo: https://cloud.mail.ru/public/5z6s/35cewkshm Schematic: https://cloud.mail.ru/public/4oRK/DQjW2h9pK It is believed the R-108 was based on the design of the CCrane Skywave and the Digitech AR-1733. The stock radio is an amazing performer.

Tecsun PL-310ET Ferrite Rod - Part II

So I decided to try the mod originally documented by Laurie Mann to utilise the spare connections on the antenna jack to bypass the internal antenna when an external one is plugged in. I suspect this is how the Tecsun PL-360 works which has the option of internal or plug-in external ferrite antennas. The PL-606 also has the external antenna jack so maybe it is mod-able too. Rather than remove the rod and swap wires, I drilled a hole and mounted a 1.3mm pcb pin to use as a solder point for the wire from the ferrite rod. Run the first wire: Then the second wire to the new PCB anchor point: Showing the new wiring in position: Don't forget to cover the base of the whip antenna with some insulation tape to prevent it shorting across the new connections. So now I can connect my new external ferrite monster rod, with a selector switch for MW and LW sections of the coil. I found that it was necessary to change the coil switch before the Tecsun MW/LW band change othe...

Tecsun PL-310ET Ferrite Loopstick Improvements

Compared to other DSP radios of similar size (PL-380, R-108...) I find my PL-310ET to be extremely deaf on MW (AM broadcast band). The longwave band is even worse. So let's take it apart and see what can be done. The poor-quality ferrite bar is shaped like a banana. I borrowed the ferrite antenna from a rotating loop desing I buit a few years ago. After removing the connections to the internal loopstick, I found it worked quite well on the LW coil section. So I ordered a larger 10-inch monster rod which seems to work quite well on MW. Manx Radio on 1368kHz is a good daytime test signal, at the lower end of the band I can hear Carolone 648kHz and Spectrum 558kHz. The radio design has been around a few years so I'm sure someone else will have tried this. There are certainly some mods documented for the PL-380. Sure enough, I found an article on the Ultralights group showing how the spare contacts on the antenna socket can be utilised to switch out ...