Thursday, September 17, 2020

Radio Shack/Sangean Replacement Speakers Available

 Hello folks. Those of you who want to revive your radio's sound can purchase a replacement speaker for $24. Shipping in the US is free.

 


 Speakers available for:

  • ATS-909
  • DX-398
  • ATS-606
  • DX-399
  • ATS-505
  • DX-402
  • 20-629

The speaker requires replacement if the volume of your receiver is low and the audio distorted with a crackling or buzzing sound. Radio Shack no longer carries this specific replacement anymore, but I have a limited quantity of replacement speakers from a different source.

These speakers are manufactured by a different company with the same dimensions and audio characteristics of the original speaker. They are a direct replacement and fit inside the radio without modification or damage.

 If you don't feel comfortable opening your radio and using soldering tools, then let me do it for you for $35 plus shipping.

Feel free to contact me for details.

Thursday, May 21, 2020

Radio Shack DX-398 / Sangean ATS-909 Mods Part 4 - IF Out Mod

I am excited to share an important update with you. I will perform an IF mod to the 909. Does TP11 sound familiar? Stay tuned to this post for updates. We will use the similar location that RadioLabs used for their external FM antenna jack on the back of the receiver.

Monday, May 4, 2020

Radio Shack DX-398 / Sangean ATS-909 Mods Part 3 - Tuning Knob

The next part of this series covers the rotary tuning knob. The DX-398 has a good tuning knob, but it has an unwanted feature causing it to stop or "click" in small increments. It is hard to spin the dial freely while tuning for DX. This is due to the plastic notches or detents in the tning shaft that mate up with a half-circle in the metal retainer/spring assembly.

Arthur Hollingsworth  created a video on how to perform this mod - You can view it here https://youtu.be/53VKmO8mqTc?t=1172



Steps

  • Locate 6 solder pads on the circuit board near the LCD display light
  • Remove the solder from the 6 pad connections
  • Remove the tuning control from the board
    Copyright Arthur Hollingsworth
  • Gently pry up the 4 metal tabs on the back of the tuning control with a small, flat bade screwdriver. Use a pair of needle nose pliers to remove any bends
    Copyright Arthur Hollingsworth
  • Gently separate the metal case and plastic control housing
    Copyright Arthur Hollingsworth
  • Remove the copper section from the 4 plastic retaining posts
    Copyright Arthur Hollingsworth
  • Using needle nose pliers, gently flatten the notch that sticks up on one side of the ring
    Copyright Arthur Hollingsworth
  • Reassemble the tuning knob in reverse order noting correct orientation (note the "detent" is now removed, but is shown here for reassembly reasons)
  • After the control has been put back together gently flatten the 4 tabs back into place using the needle nose pliers
  • Resolder the control into place on the PCB
  • Check your work and power up the radio
  • You should now be able to tune much easier now


73,
Jesse W9JES

Radio Shack DX-398 / Sangean ATS-909 Mods Part 2 - LED Replacement

This is one of the easiest mods you can do to a 909. Replace those dim, lime green LEDs with white ones!

All you need to do is desolder the old ones and replace them. Be sure to note polarity as seen on the PCB.






73,
Jesse W9JES

Radio Shack DX-398 / Sangean ATS-909 Mods Part 1 - Disable Mute


This radio design was sold under several brands including Radio Shack and Sangean. Radio Shack's model DX-398 and Sangean ATS-909.


Disable muting while tuning aka "chuffing"


This radio has a similar design to the ATS-818 where the PLL muting circuit is processed by the controller chip.


Steps


  • Disassemble the radio
  • Locate  CNT2
  • Find the Black Wire connected to PIN 10 and gently pry out with a small screwdriver
  • Use some heat shrink tubing and cover up the exposed pin and tuck neatly behind radio
  • Reassemble radio and enjoy!

Sunday, March 29, 2020

What do I look for in a shortwave radio?

A common question that I've been asked on my blog. What are some features that you find very important in a shortwave radio?



My listening preferences include talk radio, news, music, digital transmissions, and ham radio voice/data. Each person has different tastes when it comes to shortwave radios and I will try to generalize my list of must haves. but know there is some bias in my opinion. I am also interested in hearing about your opinions in the comments!

Must Have Features:
  • Physical Attributes
    • Sturdy, tactile feedback on the controls
    • Feels durable, not flexible
    • Ergonomics designed for frequent operation
    • Direct entry keypad
    • Rotary tuning knob
    • Tuning in 1KHz steps
    • RF attenuator (local/DX)
  • Frequency Coverage
    • Can listen to all commercial broadcast bands and amateur radio bands up to 29 MHz
  • Audio
    • Clear and intelligible sound from internal speaker for talk and music
  • RF Selectivity
    • Ability to reduce interference from nearby stations +-5KHz
  • RF Sensitivity
    • Ability to pull in signals at 2% over the noise floor (this is subjective as some radios measure sensitivity in dBm or ┬ÁV)
    • Adequate built-in antenna(s) to receive weak signals
  •  Double conversion receiver stages
  • Single Sideband (BFO or true LSB/USB)
  • Station Memory Recall
    • Ability to store at least 10 frequencies for quick access

 Nice To Have Features:
  • Large, bright, clear, and readable digital display
  • Selective backlight on/off toggle
  • Dimmable backlight
  • RF Gain Control
  • Triple Conversion receiver stages
  • Reputable internal components including filters
  • Dual power sources (house power and battery)
  • Recharging circuit to charge user supplied batteries
  • Line out jack
  • External antenna input
  • Audio filters (bandwidth, notch,tone)
  • RF Sensitivity to pull in signals below noise floor
  • Built in DSP signal decoders (DRM, CW, RTTY)

Friday, March 6, 2020

Radio Update

I've been very fortunate to pick up a "blue label" Sangean ATS-505 and Radio Shack DX-398 / Sangean ATS-909 this week. Both radios are expected to be delivered next week.






The current "red label" ATS-505 that I own has a bad encoder. I bought a replacement online, but it needs to be modified to work with the radio. The DX-398 has a deteriorated magnet in the speaker (common problem). My initial plan is to use the speaker from the ATS-505 "red label" for the DX-398.

I don't know if I will eventually repair the "red label" ATS-505 or just use it for parts in the DX-398 since many of the components are the same.

The good news is that I will be able to provide more content to you including modifications, enhancements, and repair information! Stay tuned!


73,
Jesse W9JES

Friday, February 28, 2020

Mods for the Radio Shack DX-402/Sangean ATS-505 Part 1 Disable Mute

Intro

 

 

 Great news to all my followers as I picked up a Sangean ATS-505 shortwave radio this week. I did not hesitate to perform a quick function test, listen to a few stations, and familiarize myself with the radio. My first impression - Not bad! I couldn't wait to get the screwdriver out and a schematic on the screen!

This radio design was sold under several brands including Radio Shack. Radio Shack's model DX-402 and a later version under catalog number 200629 (20-629). This design was also used in the Roberts R9914 and Sangean ATS-505P. It appears that the Radio Shack 200629 and Sangean "Blue Label" ATS-505's incorporate a different AF chip for better sound. The processor was also reprogrammed to eliminate chuffing as well.

It is a fairly decent radio overall with exceptionally great AM/FM sensitivity for DX'ers. I don't test LW in the United States, but shortwave reception is on par with my Grundig G5.

There seems to be challenge to find the best portable radio when it comes to features, reception, audio, and size, however this receiver performs well for it's size and provides some nice features.

Disable muting while tuning aka "chuffing"


This radio has a similar design to the ATS-818 and ATS-909 where the PLL muting circuit is processed by the controller chip. In this case, it is a Toshiba TC9327F 4-Bit Microcontroller.

Pin 52 of the microcontroller is the Mute I/O port that connects to Pin 5 of CON2. Removing this single wire connection allows the radio audio (AF) to be heard while tuning or scanning.




Steps

  •  Detailed disassembly instructions here https://earmark.net/gesr/2000629.htm
  • Remove all batteries from the radio
  • Rotate the whip antenna up a few inches.
  • Locate and remove 5 screws ( under whip antenna has a short screw, middle and bottom screws are longer, and one near the antenna base) Do not remove the screw which does not have an arrow pointed to it. This is used to secure the antenna
  • Remove the rotary tuning knob by gently pulling straight off (don't lose the plastic washer under this knob because it is used to prevent dust and direct moisture from entering the radio
  • Use a plastic pry tool or small flat blade screwdriver to gently pry apart the radio at the seam. There are several plastic tabs securing the radio. Go slow! There are two tabs on the bottom, one tab on the ext antenna jack side, and one tab on the top of the radio.
  • Remove the front of the radio and fold it over as not to interfere with the speaker wires.
  • The display (controller board) is held in place with two screws. Remove them.
  • Locate the 3 tabs on the bottom and two tabs on the top of the board. Gently pry back the tabs while lifting the circuit board up (Push the lock slider out of the switch while moving the board up
  • There are two connectors attached to the controller board. Lift up the bottom of the board to gain access to Connector 2 (CON2)
  • Notice the red wire and 14 white wires. The red wire should be at pin 1 (left side of the radio as you are looking at it)
  • Count the wires from left to right and stop at #5. This is the wire you need to cut or remove from the socket
  • Cut the wire and secure the ends with tape or heat shrink tubing
  • Reassemble the radio in reverse and enjoy!

73!
Jesse W9JES



Tuesday, February 25, 2020

SWL'ing Website - All Things SWL!

I would like to extend my gracious thanks to Martin at SWL'ing Blog who shared information about my radio modifications. His website has an amazing set of content from SWL news, articles, radio reviews, recordings, videos, frequencies lists, and more!



73,
Jesse W9JES

Thursday, February 6, 2020

Repair and Modification Services

I've had several inquiries about performing these modifications on other radios. I would be more than happy to provide this service to fellow shortwave listeners and/or ham radio operators.

You can choose from the list of modifications below. I accept Paypal and Money Orders for payment processing. The prices below do no reflect shipping costs to/from my customers.


Radio Shack DX-390 / Sangean ATS-818
  • Anti-Chuffing (Mute) Mod $20
  • Disable Keypad/Band Beep Mod $10
  • Static Protection Mod $30
  • Light Switch Mod $60
    • Includes lamp replacement with white LED
    • Includes lamp switch interface
  • PanAdapter Mod #1 $55
    • Includes SMA connector jack circuit installed on the side of the radio
  •  PanAdapter Mod #2 $80
    • Includes SMA connector jack circuit
    • Includes DVB-T Style SDR and connection cables (add $35 for upgraded SDR)
    • Includes instructions for installation, configuration, and using the HDSDR interface
  •  Bronze Package $45
    • Includes Anti-Chuffing Mod
    • Includes Static Protection Mod
    • Includes Beep Mod (Optional)
  •  Silver Package $100
    • Includes Anti-Chuffing Mod
    • Includes Static Protection Mod
    • Includes Beep Mod (Optional)
    • Includes Light Switch Mod
  •  Gold Package $150
    • Includes Anti-Chuffing Mod
    • Includes Static Protection Mod
    • Includes Light Switch Mod
    • Includes Beep Mod (Optional)
    • Includes PanAdapter Mod #1

Other services offered
  • Battery corrosion removal $25
    • Includes cleaning.adjustment of battery terminals
    • Reflow solder joints
    • Resistance/Drain Test
  • LCD Display brightness/clarity restoration $60
    • Includes LCD removal and cleaning pads
    • Check/Replace Resistor Ladder Components
  • Deaf shortwave band repair $60
    • Diagnose/Replace  JFET and/or diodes
  • Switch/knob cleaning/repair $30-$50
    • Deoxit/Cleaner designed for circuit boards

Radio Shack DX-402 / Sangean ATS-505
  • Anti-Chuffing (Mute) Mod $20
  • Disable Keypad/Band Beep Mod $10
  • Static Protection Mod $30
  • White LED Mod $30
    • Replace green LED's with white LED's 
  • Speaker Replacement $35

Radio Shack DX-398 / Sangean ATS-909
  • Anti-Chuffing (Mute) Mod $20
  • Remove detent from Tuning Knob $30
  • Disable Keypad/Band Beep Mod $10
  • Static Protection Mod $30
  • White LED Mod $30
    • Replace green LED's with white LED's
  • Speaker Replacement $35


You can email me for more details, questions, and information using the contact form on my blog.



73!
Jesse,W9JES

Wednesday, February 5, 2020

Tuesday, January 14, 2020

Mods for the Radio Shack DX-390 / Sangean ATS 818 Part 4 Panadapter

The next mod in this series is going to show you how to add an IF-Out Connector to your radio that you can interface a SDR receiver and use it as a panadapter! A panadapter is a device that gives you a visual display of the radio spectrum in a waterfall or line display and "capture" the audio from your radio at the same time. using a cheap SDR unit.

The benefits of using a panadapter are endless. You can get an idea of where activity is on your shortwave radio with a wider view of the radio spectrum. For example, you can tune to 6.060 MHz on the radio and see up to 2.8 MHz of the radio spectrum above and below that frequency. If you are chasing DX or following ham radio operators, then you can find out where the bands are active. Other benefits include digital mode decoding for DRM, RTTY, WeFax, JS8Call, Morse Code, PSK, and more.

A panadapter allows greater flexibility with digital signal processing giving the listener more filter options, decoders, and plugins. Many high end receivers and ham radio transceivers now offer an easy way to connect panadapters or rig interfaces to your favorite computer. You can also use the panadapter as a second audio processor/receiver by listening on two frequencies at the same time.



I recommend the RTL-SDR Blog V3 which includes direct sampling of HF frequencies below 24 MHZ if you choose to use it without the ATS-818/DX-390. These units will cost about $22-$25 or you can buy a complete kit with antenna for $30 from https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles You can also use the $8 DVB TV tuners to interface to your radio found on eBay. I tested both HDSDR and SDR# on my laptop and found that HDSDR works a bit better for this application because you can tune below the radio frequency. HDSDR can be found at www.hdsdr.de

What you need to perform this mod..
  • SDR as mentioned above
  • Necessary cables to connect the SDR to your radio (I used a pigtail cable with a female SMA connector and SMA male/male adapter) available on Amazon.
  • 1 k ohm resistor
  • 1 nf to 2.2 nf non polarized capacitor (I used a 2.2 nf film capacitor)
  • Drill/hand tools/soldering iron/heat shrink tubing

The DX-390 is a dual conversion, superhetrodyne receiver design. One thing that makes this radio great is hardware filtering. Looking at LW/AM/SW circuit in particular, there is a Murata crystal filter in the first IF stage and two Murata ceramic filters at the 2nd IF stage. The first IF is 55.845 MHz and the second IF is 450 kHz. We want to use the 1st IF stage for our panadapter.



For some reason, the second tuning coil (T2) was omitted in final production. We can use this for our IF tap.

Connecting your SDR directly to the radio could alter the IF stage and cause poor reception. It could also transfer unwanted DC voltage between the radio and your SDR. This is why we use a small value capacitor for blocking harmful voltage and resistor to prevent receiver sensitivity drain. Connect them in series to your radio.






Finding the correct tap point for a strong IF signal in this radio is fairly simple on the Sangean. We could tap between T1 andT3 or the output of Q3 and Q4 and receive a great signal. I decided to use the omitted T2 circuit where it connects to R39.




After cutting the cable to the correct length, I stripped and soldered the center conductor of the coax to the capacitor/resistor. I also cut the braid back since it isn't needed for the signal path and could induce noise into the IF output. You could install a ferrite core choke on the cable as well.



I decided to drill a hole in the side of the radio for easy access to the IF stage. A 1/2 inch bit was sufficient to get the connector through the radio body. It lines up perfectly with the other connectors.



Time to attach my cable to the radio.




Reassemble the radio and connect the SDR units! Both work fine for this application, however, the temp controlled oscillator is superior in the RTL-SDR V3 unit to prevent drift.


Fire up the software. Use HDSDR and install the correct ExtIO for your SDR. Files and instructions are available at www.hdsdr.de/hardware.html




Configure the bandwidth and AGC settings as shown in HDSDR. Choose 2400 or 2800 kbps for the sample rate.


 Setup your receiver in the RF Front End configuration menu. Set your SDR to receive the IF output and type 55845000 in the IF frequency box. Check the "mirror RF Spectrum in general" box.



After connecting all cables and running software, turn on the ATS-818/DX-390 and adjust the RF gain as appropriate. Tone, Volume, BFO, Narrow/Wide controls don't affect the signal to HDSDR. You can set those to your preference.  Now set a frequency on the radio in LW/AM/SW mode. An unused frequency is preferred somewhere within the band you would like to listen to. You will get 2.4 to 2.8 MHz of bandwidth to HDSDR that you can independently tune and listen. In HDSDR, you want to set your LO as the same frequency displayed on your radio. Right click to lock the LO frequency to prevent it from accidentally changing as you tune in the application.









73,
Jesse W9JES

Friday, January 10, 2020

Mods for the Radio Shack DX-390 / Sangean ATS 818 Part 3 Static Protection

Do you want to protect your radio from static discharge while using the whip antenna? This is a must-have mod for the radio because the existing design does not incorporate static protection on the antenna input circuit. Some folks have found their radios to be "deaf" on AM and shortwave bands because a static pulse could destroy the sensitive Q1 transistor. This usually occurs in low humidity conditions when a person touches the antenna to adjust it.

You will need (2) 1N4148 silicon (signal) diodes or equivalent and a short jumper wire to complete this mod.

Note: This does not protect the external antenna jack so I recommend using the same circuit between the 1/8" mono jack and your wire antenna.




Do you already suspect that your radio has a blown out transistor? Here are some tips from AA1LL on QSL.net to test and replace the transistor. 

"This relates to the front end burn-out phenomenon associated with the Radio Shack DX-390 multiband receiver. This happened to me with all the previously documented symptoms and I was able to repair it by replacing the input FET with a device which is available off the shelf from Radio Shack.
After taking the DX-390's plastic enclosure apart by removing all the black self-tapping screws (don't forget the one down in the battery compartment) and lifting up the single p.c. board by unscrewing all the silver colored screws which hold it down, you will find Q1 near the antenna connector which in my radio was a 2SK152. Remove the dead Q1 by sucking the solder off of its p.c. pads with solder wick and measure it with the DVM to make sure it is dead--mine looked like a 31-ohm resistor from drain to source. A good FET would look like a pair of diodes with their anodes connected together at the gate. The gate is the lower terminal looking at the device from the bottom with the flat side to your right; 

Paul Gili, AA1LL"


73,
Jesse, W9JES

Mods for the Radio Shack DX-390 / Sangean ATS 818 Part 2 Lights

WOW! Almost 10 years to the day and now it's time to provide an update to the trusty old ATS-818/DX-390 mods. Thanks for sticking around with me and being very patient as I was away taking care of life's impromptu moments.

It feels like things are winding down a bit and I've been more active in the SWL hobby once again. One of the things that sparked my interest was a great opportunity to pick up a Gundig G5 in excellent condition for $30 late last year. It was one of those situations where someone knew that I was a ham radio operator and said their friend had some old radios from a friend who recently passed. While I do like the size and sensitivity of the G5, it lacks some features on the DX-390 such as an excellent speaker for great sound and tone controls. The G5 goes with me on trips where size and weight are key factors.

Back to the 818/390. This project started out as a means of improvements to an already impressive radio. I liked most of the features on the radio, but wanted to squeeze out all of the potential it had. The next enhancement that I completed on the list was replacing the dim incandescent light and adding on-demand light control. For this task, I researched the radio schematic and attempted to make heads or tails of the  circuit. The 3 transistor circuit connects +6v to the lamp when the light button is shorted to ground. Capacitor C414 and C415 play a significant part in this circuit as they are responsible for triggering the transistors. Their values can be substituted with smaller or higher values to change the delay in trigger and duration. I replaced C415 and tested this theory with success. This circuit could also be rewired using the same components with some jumper wires and cutting traces to achieve my goal, but I chose to leave it as-is to avoid risk of permanent damage to the PCB.

Next, I looked at the Toshiba TC4S11F NAND gate (used in other radios) as a solution to my problem. This would work!



A little more digging and I stumbled across the KY002 Bi-Stable switch. Could it be that easy? Yes! The KY002 or KY002S variants use a trigger circuit to connect vcc to output 1 via a single trigger shorted to ground. The output is toggled on/off each time the momentary button is pressed. The KY002 can handle the voltage and amperage requirements for the light adequately.



Before wiring this module to the radio, I decided to replace the incandescent light with a frosted white, 5mm LED. The LED is brighter and drains half the current of the incandescent. I used a 1K Ohm resistor to suit my brightness tastes (the 2.2K resistor in the pic was swapped out because the LED was too dim).


Here is the radio schematic and wiring diagram to the KY002. Brown and red wires connecting the existing lamp circuit can be used to drive the KY002 and LED. This bypasses the old light circuit leaving it in place to revert it back to factory as desired. The only parts of the existing circuit in use are the light switch and ground pad of the old lamp.

Brown and Red wires connecting to old lamp circuit were cut and removed from here. The metal shield needs to be removed from the main PCB to gain access. Desolder or clip the wires closest to the board and solder them to the KY002.




The existing light switch needs to be connected to V1 of the KY002. There is a convenient thru-hole solder pad available next to R423 (104) that can be used.


Ground for the light switch can be found at the existing lamp location here. Lift up the tab that covers the old lamp. Connect this pad to GND of the KY002. Now is a good time to remove the old lamp and solder the short side of the LED to the same pad that you use for GND. I bent the leads to figure out best placement. You can use the white foam to support the led and a little hot glue to secure it.


I ran all the wires to the back of the board and attached the KY002 using double sided foam tape. Here you can see all 5 wires routed and soldered into place. I used scotch tape to hold down the wires, then reattached the metal RF shield.


The KY002 modules can be found on eBay or other Arduino parts retailers.. I paid about $2 per module.

Results!



So what's next for the 390? One possibility is an IF-Out mod and create a panadapter for my laptop/SDR dongle.



73,
Jesse W9JES