Layered Caramel Macchiato

I may be spending a bit too much attention to preparing my morning espresso

espresso, milk, caramel
espresso, milk, caramel

A $35 paint gun that’s good

good HVLP paint guns need not be expensive
good HVLP paint guns need not be expensive

Three years ago, I walked into an automotive pain shop and asked if they could recommend a good paint gun. I’d been using a cheap one and my results showed. I decided I’d better get a good one, even if it would cost me $150 or more. I’d read the reviews and most were suggesting a $210 spray gun.

The older gentleman at the shop said, “I can sell you an expensive gun but this is what we use” and he pulls a plastic wrapped run off the display sales shelf. The AES 507 was just $35.

The man also asked how I cleaned and maintained my paint guns and then showed me a simpler way. I took the gun home and used it for EVERYTHING.

I shot lacquer and urethane and epoxy and even latex. The results on everything from wood to aluminum were great. The latex took its toll on the gun and while it still works well, I decided I may as well pick up a new one for the next project. (I relegate the old one any latex paint projects.)

I prefer an aluminum hopper and will likely transfer it across to the new gun but the plastic works just fine.

The quality and quantity of the air supply is important as is the condition of the space you use to spray. All those being equal, you don’t require a high end big ticket gun to get great results.

What’s It #21 – an RF dummy load

RF dummy load for transmitter testing
RF dummy load for transmitter testing

I’m about to start testing a remote COMM radio and remote transponder. Given they must be “active” to respond to the main control system, the transponder will go “live” and transmit as part of the testing. Similarly, to verify the radio it too will need to transmit.

Given these tests, the general convenience of having a transmitter test load, the relative easy of acquiring parts ( & assembly, I decided to build rather than buy.

The design consists of 20 1K ohm 3 watt resistors all in parallel. This total 60 watts at 50 ohms. This is submerged in a quart can of oil to dissipate heat. The effective rating is safely 120 watts and higher loads for short transmission.

The total cost was $12 for one hundred resistors, $7 for five BNC connectors, $1 for each of the quart paint cans, $9 for a 6″x6″ sheet of 20 AWG brass, and $2.75 per quart of light weight motor oil. While the two dummy loads technically cost me $17.75 each, the next two (if I needed them) would only cost me an additional $3.75 each.

What’s It #21 ?

I need two of these and rather than spend $40 – $50 each I decided I’d build them. Here is one.

What is it ?
What is it ?

Garmin understands amateur aircraft builders

For anyone who has worked with Garmin’s prior generation of aircraft avionics, they are all too aware of the challenges of wiring high density D-Sub pin connectors, threading back-shells, and conforming to old standards. So I keep being amazed by the small changes Garmin has made with their latest generation of avionics targeting the amateur home built aircraft community.

I’m very grateful for the switch to standard D-Sub pins and the open top connectors makes the assembly much easier. And here is another example of Garmin thinking like a builder rather than an engineer – mounts which can be switched from the ends to the sides of their new remote mounted radio.

When building a kit plane, everything is up to the builder and this means every airplane is a bit different with hundreds of decisions.

In my RV-8, finding a location for the remote radio was becoming a challenge of compromises. I finally located a suitable space but the radio mounting tabs were in the wrong place to make it work. I was about to concede and build new mounting tabs but when I removed the factory tabs I discovered Garmin had anticipated my need!

With the factory installed mounting tabs at each end of the radio, it can be mounted horizontally or vertically with ease. In my case, the problem was that I needed to mount it across between the RV-8’s forward baggage bulkhead and the Z-brace. Ideally, I wanted those tabs to be on the sides of the radio rather than the ends. Thankfully, Garmin attached the mounting tabs with screws. When I unscrewed the tabs I was delighted to see that Garmin had designed the tabs’ screw locations and the radio’s screw holes (two extra ones hidden under the tabs in their original locations) to rotate 90 degrees and re-attach! All I had to do was unscrew the tabs, turn them 90 degrees and there were nut plates already installed for the alternate orientation.

Garmin had designed the radio to give the builder multiple choices for how to install their radio.

This truly is an example of designing for their end user!

GTR-20 with adjustable mounting rails
GTR-20 with adjustable mounting rails

A 6PDT push button for COMM1/COMM2 radio switching

switch stereo audio, mic, and signals
switch stereo audio, mic, and signals

Traditional aircraft used an audio panel in the avionics stack to handle multiple radios, audio sources, and intercom between the occupant headsets. This was logical when there were so many audio sources which needed to be monitored for different segments of flight – two radios, identifying VORs and NDBs, listening for the outer marker signal, etc.

With the growing availability of GPS for all segments of flight including precision landing, some aircraft have done away with an ADF and even NAV radios. My plane is one of these. There are pros/cons to this configuration but for a lot of domestic flying, it’s safe and complete.

Many newer radios incorporate the intercom and even have alert and auxiliary audio inputs. With all of he capabilities of these modern radios, most of the audio panel capabilities are redundant. The exception is supporting two radios.

Two radios are handy since one radio should always be setup to talk to the airport or to air traffic control. The second radio can handle things like checking weather at the departure or arrival airport. It can also be helpful when you know you will be changing frequencies multiple times in a short period – eg: weather, clearance, ground, tower, then departure control.

Having two radios doesn’t dictate an audio panel. Switching frequencies has become much easier with database integrated radios and EFIS/GPS connected radios. With these systems, a frequency change is often a press of a button.

This leaves the listening to weather and the “convenience cases” when you want to load up clearance and ground to a second radio. The “listen” to the second radio can be handled through an auxiliary input on the primary radio. Now we have only one case to solve – temporarily switching to the second radio.

In a side-by-side airplane, both occupants have access to the panel but in a tandem (or solo) only the pilot can reach the panel. Only the pilot really needs access to both radios. My airplane is a tandem and I fly 99% solo.

A pilot headset has a MIC, a push-to-transmit, mono or L/R headphones, and the ground wire. That’s 5 connections. A switch can handle toggling all 5 wires at once between two radios.

The sixth switch lets us listen to the second radio while connected to the first.

Below a video of the switch. The switch has both solder lugs and PCB pins. The pins can be cut off when using the solder lugs. The push button switch “latches” when pressed and releases when pressed again. It has a mechanical colored indicator that is visible when pressed to the “latched” position.

6PDT Push Button Switch