Many because of SWLing Submit contributor Steve Allen (KZ4TN), who shares the next visitor put up:
by Steve Allen
I got here throughout this HF Sign Enhancer for SDR on the RTL-SDR.com web site. It was designed and constructed by Peter Parker, VK3YE from Melbourne, Australia. Under is the hyperlink to the video of the sign enhancer in motion utilizing an RTL-SDR V4 Software program Designed Radio;
www.youtube.com/watch?v=W6OXc_wZTXU
It was very straightforward to see and take heed to the advance to the sign reception the sign enhancer made. Having been a life-long shortwave listener and present SDR person, I needed to construct one.
I did a display screen seize of the schematic, re-drew it utilizing MS Phrase, and constructed the invoice of supplies. In Peter’s unique design he included a T-R relay so you would use the SDR together with a transmitter, which I opted to go away out. I had the passive elements in my “junk field” however needed to supply the enclosure, controls, and antenna connectors. I’ve used these clam shell extruded enclosures with earlier tasks and love the construct high quality and the truth that they incorporate a slot within the sides which let me insert a sheet of PCB materials on which I can do the meeting.
Referring to the schematic drawing in Peter’s video, you possibly can see that the variable capacitor “floats” above floor, which isn’t the standard software for these units. To do this I mounted the vari-cap on a bit of non-plated PCB materials that I reduce to the width of the enclosure and it match properly throughout the slot. The vari-cap had three pins on the aspect of the body that allowed me to power match it into three holes I drilled within the PCB materials. I used to be very cautious to drill the holes undersize after which slowly open them up till the vari-cap press match on to the board. For good measure I ran UV curing adhesive down into every gap, letting it stream throughout earlier than I set it with a UV gentle supply.
I then drilled an outsized gap within the entrance panel for the vari-cap shaft to go by way of.
I then mounted the RF achieve and band swap. The subsequent step was the meeting of the AM broadcast filter. As SDRs may be overpowered by native AM radio stations Peter select to incorporate an inner band go filter that’s configured for round 3.5 MHz. The intent of this filter is to attenuate the alerts under 3.5 MHz. Sturdy AM stations will nonetheless be heard however there may be a lot much less likelihood of them bleeding by way of on the upper frequencies.
I assembled the filter on a bit of perf board and related the element leads on the underside. I handed leads again up by way of the perf board for the sign path and floor. I mounted it on the principle board with a standoff.
The subsequent step was the wiring of the inductors to the rotary swap. Easy, and I tied them to the vari-cap body.
For the again panel I selected an SO-239 and a BNC for the antenna enter, and for the radio connection an SMA and one other BNC. I sanded off the coating on the enclosure on the antenna mounts in addition to the 4 corners the place the again panel screws into the highest and backside of the clam shell enclosure to offer good grounding of the enclosure. I wired the 1N4148 diodes on the antenna connectors, and connected the RG-174 coax. As Peter urged, I grounded the lengthy (comparatively talking) runs to and from the again panel with coax and grounded it on the again panel.
The final step was to use a little bit of epoxy adhesive to the fiberglass board and the slot it runs in to carry it in place. As soon as the epoxy set, I did the ultimate wiring of the entrance and rear panel elements. You possibly can see how I sanded the corners of the again panel within the above picture.
I related it to my inverted L antenna and an SDR Play RSP2 and gave it a check run. I like the truth that I can visually see the adjustments to the sign energy on the SDR software program in addition to audibly. It makes a noticeable enchancment to the reception.
Thanks Peter. I loved the construct.
Steve Allen, KZ4TN
