Friday, February 6, 2015

A Collection of Mods for the DX-390 / ATS-818 Part 2.5

First I'd like to apologize for the delay in posting my light mod. I am the type of person who can't leave well enough alone :)

The radio is still in pieces on my bench and I asked myself if there were any other mods I'd like to do while I had it open.. Well of course! Another feature I added to the "nice to have" category is a way to remotely control the radio in some way. You see, I use this radio on camping trips with my kids as well as casual shortwave/HAM listening. Wouldn't it be cool to be able to change frequency, volume, etc with a remote control?

I remember the "new and improved" Bose Wave radio commercials which show new features such as a remote control, espresso maker, and pizza warmer. (Maybe I am exaggerating a bit on the espresso and pizza functions) So why not add this to my DX-390?

I have several remote controls laying around in junk drawers and think I have one that will work for this project. The next step is to incorporate an IR receiver circuit to interpret different functions of the IC and/or buttons. I plan to share my trials and errors with you along the way. (I better stop with the mods at this point before I add a WIFI interface to connected to HRD or perform an IF mod to for a spectrum scope, hi-hi)



Thanks,

W9JES

Thursday, January 8, 2015

A collection of radio modifications for the Sangean ATS 818 aka Radio Shack DX-390 part 2 UPDATE

I will be digging out the schematic for my DX-390 and tinkering with the radio again. This time I will take pictures and share how to modify the backlight to work one of two ways..

1. Replace a component to extend the time from 15 seconds to whatever you like. Such as 15 minutes.. (I currently have this mod in my radio)

OR

2. Add a latch circuit to control the function of the light switch to allow it to be on/off with a press of the button. I am in the process of researching this functionality using a 555 timer or transistors. Please comment if you have any simple circuits requiring only a few components capable of operating on 6 volts.


I may also add information on how to replace the stock, incandescent lamp with a LED while the radio is on my bench. Stay tuned!



73,

Jesse, W9JES

iPhone and Ham Radio - A Realization

I wrote this editorial in 2010 as a response to the great debate over the Echolink smartphone apps..  Figured I would publish it here now to see what your perspective is on this technology 5 years later. Feel free to comment.


Ham radio has many facets which makes it an enjoyable hobby. Homebrew and experimentation are two of them. How does the iPhone fit into this? It is not a ham radio, although it uses RF. I see the iPhone as a neat piece of technology that has apps for everything. That's great, but what about ham radio apps? There were over two dozen apps that I saw for ham radio and one of the newer apps is Echolink. This allows people to talk to each other on the Echolink network through their phone over a wifi network. I've recently talked to people on Echolink who were using the iPhone and the audio quality is great. I guess Apple put good mics in the phones.

After the brief wave of astonishment escaped my face, I started thinking about the good, bad, and ugly of using a smartphone for amateur radio. Back in the good old days of ham radio there was a device called an auto-patch. The auto-patch was used for making land line phone calls via a handheld or mobile radio, typically through a repeater. The repeater passed DTMF tones to the auto-patch, then to the telco. Audio was transferred using half duplex and it worked fine as long as the connection to the repeater did not drop. This was a really cool way of talking to friends and family as long as you didn't care who listened in. Before cellphones became popular, this was an elite technology to have. Did that just sound like the opposite of the iPhone Echolink app? It sure was!

I guess my point is RF links to land line connections existed for decades. We've just figured out a way to re-purpose them, right?

Now I don't think the autopatch hurt the hobby because it was heard by anyone on the frequency. This limited the amount of time spent on the "phone" as well as controlling the types of conversation. Is the iPhone good or bad for ham radio? Here is my observation..


Smartphones are evolving into handheld computers.

This is true and we have no way of knowing how far it will go. I have an Android smartphone which has a web browser, email, texting, music player, GPS, games, productivity apps, a full keyboard, wifi, and more. How much more can they cram into these devices? Those of you who use Echolink know it has to be connected to one of the designated servers using a computer with Windows or Linux. If your smartphone has a WiFi connection, how is it any different from a laptop or desktop pc?

The Bottom Line

Is Echolink still ham radio? I think so. It is a form of ham radio utilizing new technology. On the other hand, I believe that a ham radio operator should also continue to utilize our allocated RF space as well. Especially while it is still available to us. I'd hate to see the bands re-provisioned for non-amateur use.


73,

Jesse, W9JES

Friday, November 26, 2010

Socratic Forum

I have been a member of the Socratic Forum for almost 2 years and it has been great to me. I've received $140 for taking short surveys about information technology, consumer goods, health care, travel, food, entertainment, etc. The surveys range from 5 minutes too 20 minutes and arrive in my email ever week. I consider myself a skeptical person by nature and this company proved its worth. The Socratic community is a great way to pickup some extra spending money for radio gear and other things. I can choose to either receive a check or Amazon gift cards.


Here is an expert from their website..

Socratic Forum members participate in state-of-the-art Web-based surveys about the hottest new technologies and software, e-commerce innovations, business-to-business products and services, and forces driving the global economy. Survey participation is always 100% voluntary, and all information provided to us remains confidential. In exchange, we reward our members by offering access to new information and/or opportunities to receive cash, online gift certificates, and other rewards.



I reviewed their privacy policy and feel comfortable with it. That statement carries a lot of weight because I am an IT Network Security Analyst and would not sign up for something if it looked fishy. Feel free to join the Socratic Community and get paid for your opinions. This is the only "survey" community I joined because of is record and history. Here is the link to join.. Remember it is free!


73,

Jesse, W9JES

Sunday, January 17, 2010

A collection of radio modifications for the Sangean ATS 818 aka Radio Shack DX-390 part 1

Let's start out with a collection of radio modifications for the Sangean ATS 818 / Radio Shack DX-390 world-band receiver. I've owned my DX-390 since 1993 and it is a great radio that I would put in the "middle class" range compared to other portable receivers. It has some nice features such as single-sideband AM (SSB) reception and strong FM reception as well as a decent AM band. This radio has a surprisingly good sound coming from the 4 inch speaker. It has a tone control to shape the audio as well. Drawbacks include an over-sensitive shortwave circuit which easily picks up static and nearby noise as well as limited filter functionality. It also mutes the audio while tuning and scanning for DX. The backlight only stays on for a short time and is not adjustable. I find myself pressing the light button a lot when tuning in the bedroom.

The good thing about this radio is most of the drawbacks can be fixed to make it a much better radio overall. Here are some enhancements for this radio.

As I mentioned earlier, the radio mutes the speaker when tuning. This is extremely distracting when trying to find DX stations or tune SSB. There are two ways to fix this problem. The first is to use headphones and turn on the volume while tuning/scanning. You will be able to faintly hear the audio, but will get a blast when you stop tuning. Instead of taking the risk of becoming deaf, try this easy modification to disable to muting. It takes about 10 minutes to do this mod after waiting 30 minutes to discharge the capacitors.

DISABLE AUTO MUTE

Minimum tools required: Phillips screwdriver, wire cutter, electrical tape.

Time required: 10 to 40 minutes

Side effects: Changing bands or turning the receiver on/off could cause a loud noise if speaker is turned up.


Procedure

  • Disconnect all power from the receiver including the D and AA batteries for 30 minutes before opening the case. This is necessary to discharge the memory backup capacitor.
  • Remove the volume knob by pulling it straight out.
  • Turn the receiver over and remove 5 black screws. One of the screws is in the battery compartment.
  • Seperate the two halfs of the receiver and lay the radio back down on its face.
  • Locate and remove  5 silver screws from the circuit board.
  • Gently flip over the circuit board while making sure not to bump the AM antenna wires. You will have to slide it sideways to clear the headphone and ext antenna jack.
  • You will notice two connectors near the bottom of board nearest to the battery compartment.
  • Locate the connector CNT1. This is a multi-wire connector that has 12 pins. The pin numbers are printed on the board.
  • Cut the wire going to pin 10. Make sure to leave about 2 or 3 inches of wire to the connector in case you want to reverse the mod.
  • You now have two options - protect the wires from shorting or add a switch.


    Option 1:  Reassemble the receiver and enjoy DX hunting

    • Apply electrical tape or heatshrink to prevent the cut wires from shorting.
    •  Place the circuit board back into place and secure it with the silver screws.
    • Put the back of the receiver on and secure with the black screws.
    •  Put the batteries back in and turn on the receiver to test it.
    • If you are having trouble hearing stations on shortwave or AM after the mod, remove the batteries and let the radio sit without power for 12 hours. This is caused by a processor lockup and the reset is needed.

    Option 2: Add a switch to enable/disable the mute function externally
    • If you cut the wire towards the middle, you know have enough slack solder the wires to a SPST switch.
    • The switch can be added right between the tuning and volume knobs. I recommend using a switch available at Radio Shack, model number 275-406. This is a pack of two switches for under $3.
    • After the hole is drilled, solder the wires to the switch and attach it with some hot glue, screws, or rivets.
    •  Place the circuit board back into place and secure it with the silver screws.
    • Put the back of the receiver on and secure with the black screws.
    •  Put the batteries back in and turn on the receiver to test it.
    • If you are having trouble hearing stations on shortwave or AM after the mod, remove the batteries and let the radio sit without power for 12 hours. This is caused by a processor lockup and the reset is needed.
    Your receiver now has the capabilities of higher end equipment. Enjoy DX hunting! The next part of this series will cover the backlight timer. I will show you how to extend the 15 second limitation of the backlight.


    73,

    Jesse, W9JES

    Welcome - A Short Introduction

    Welcome to my amateur radio blog. The purpose of this site is to discuss and share information about amateur radio, shortwave listening, computers, and other technologies. Feel free to share your thoughts.


    73,
    Jesse, W9JES