DIY Arduino TNC

I have finished building and testing a DIY Terminal Node Controller (TNC). With a TNC, any radio may encode and decode signals in the Automatic Packet Reporting System (APRS) format. This TNC is based on the home-brewed TNC project by VK3DAN.

Arduino-based TNC

The TNC requires a smart phone with APRSdroid connected via bluetooth. It taps directly to a radio through the dedicated audio line-in and line-out ports. I’ve tested this TNC to work with the International Space Station’s (ISS) digipeater at 145.825 MHz, using the digipath: ARISS.

Related links:
DIY Moxon-Yagi Satellite Antenna
Portable Satellite Radio Setup

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

DIY 40-Meter Antenna

I’ve built a simple HF (40-meter band) wire antenna with some scrap wires, a length of RG8 cable, PVC pipe as insulator, and some way of securing and making it waterproof. This antenna is intended for receiving (RX only) so I could listen to local voice and Morse code net calls using a Software-Defined Radio (SDR).

Homebrewed 40-meter band wire antenna

The antenna is a dipole with 10 meters of conductor on each side. One conductor is soldered directly to the coax’s outer conductor (braid), while the other conductor is soldered to the coax’s center conductor. I did not use a balun for this antenna, but you may try to use one. Each end of the conductors terminate with a PVC insulator. If you plan on transmitting with a wire antenna, you will need to adjust the length of each conductor for best SWR. I will be using this antenna with an HF radio to send and receive signals in the 40-meter band (7.000 to 7.200 MHz).

To watch a video about this DIY 40-meter antenna, click here.

Related links:
DIY Moxon-Yagi Satellite Antenna
Portable Satellite Radio Setup

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

Canon 450D, 1000D, and 1100D DSLR Filter Modification

I have performed filter modifications on a number of DSLR cameras for me and my colleagues. It involves the removal of the stock UV-IR filter, making the camera more sensitive to H-alpha wavelengths. This modification is helpful only when shooting targets with H-alpha emissions, as Canon’s standard (stock) filter blocks this part of the spectrum.

Here are sample images taken with the modified cameras. Take note of the shift in white balance (reddish hue), which is to be expected in this type of modification.

To view posts on DIY projects and astronomical equipment, click here.

Related link: FujiFilm X-A1 Filter Modification

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

DIY Guide Scope Rings

Guide scope rings or guide rings are mechanisms used for mounting guide scopes. A guide scope is a telescope used to monitor tracking accuracy while a main telescope takes a long-exposure photo. Errors in tracking are detected with a guide scope by monitoring a guide star. Corrections are made by the mount to keep the guide star centered, and thus, keeping the main imaging telescope pointed at a target for the whole duration of an exposure.

There may be instances when it is difficult to find a nearby guide star. With guide scope rings, a guide scope may be pointed, to some extent, at a part of the sky that is different from what is being photographed, allowing access to more guide stars. This DIY guide scope rings set is used with a 70 mm f/5.7 guide scope and a 100 mm f/9 imaging telescope.

To view posts on DIY projects and astronomical equipment, click here.

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

Smartphone-to-Telescope Adapter

Smartphones can be used to image the moon by holding it next to the eyepiece of a telescope. For smart phone cameras, a mid-power eyepiece such as a 25 mm eyepiece yields good results. To hold the phone camera steady while taking a photo, a smartphone-to-telescope adapter may be used.

This imaging method is called afocal imaging, in which a camera with its lens is mounted next to another image-forming optical system such as a telescope with an eyepiece or a pair of binoculars.

To view posts on DIY projects and astronomical equipment, click here.
Related link: Universal Camera Adapter

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

DIY Dew Heater

Dew heaters or heater pads are telescopes accessories used to prevent dew from forming on the telescope’s lens. During long imaging sessions, it is not uncommon for the main lens of refractors and SCTs to form dew. A heater is used to keep the objective lens at a temperature a few degrees C above the dew point to prevent the formation of dew.

I used nichrome wires from a local electronics store to build several DIY heater pads for my telescope, which I find useful in keeping the lenses free from dew especially when imaging in remote observing sites.

To view posts on DIY projects and astronomical equipment, click here.

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

DIY Plate for Telescopes

I’ve built an aluminum plate for my equatorial mount to allow it to carry the main telescope and the guide scope for autoguiding purposes. In autoguiding, it is important to minimize flexing between the imaging telescope and the guide scope, thus, a plate with suitable thickness helps address this problem. This DIY plate measures 12 cm by 20 cm by 1 cm and made from a solid aluminum plate from a local metals supply shop. Holes have been drilled on the plate to allow attachment of various loads such as DSLR cameras and different telescopes.

Kenko NES mount with a DIY aluminum plate

To view posts on DIY projects and astronomical equipment, click here.

Related link: Sky-Watcher 100ED Refractor

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

Peltier-Cooled DSLR Project

During an exposure, the imaging sensor of a DSLR warms up, resulting to noisy images. By cooling down the sensor, it is possible to eliminate or somehow minimize this thermal noise.

I have made a number of attempts to accomplish this with a Canon 450D and a Peltier module, however, it appears it is very difficult to implement without running into problems such as condensation and frosting.

M42 imaged with a Peltier-cooled filter-modified Canon 450D. No dark frames were used in this image. Image processed in SIRIL. The DSLR’s stock filter was replaced with a Baader UV-IR blocking filter.

To view posts on DIY projects and astronomical equipment, click here.

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

DIY Logitech 4000 Guide Camera

The Logitech 4000 webcam is capable of imaging planets and can be modified to take long exposure images to serve as a guide camera. The modification requires a serial port to externally control the camera’s exposure time using a guiding software such as GuideMaster and PHD Guiding.

The long- exposure modification allows the camera to detect faint guide stars, which is a useful feature for a guide camera. The diagram shown here was a modified version of M. Burri’s (2002) parallel port interface for a Logitech 3000 which I have adapted to work with the newer Logitech 4000 and a serial port.

To view posts on DIY projects and astronomical equipment, click here.

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines