Saturday, November 28, 2020

Ham Radio Movies

 Who remembers this movie? This is WM1ATE calling HB9RFX. 

High Frequency (1998)

Of course, many of you also remember the movie, Frequency (2000) and a subsequent TV series.

What other shortwave or ham radio movies do you remember?

 

Here is a list compiled by Dave, AD7DB.

"Gone With the Wind" - 1939. Drama. The classic story of Brett and Charlotte as they try to save their 100 foot tower in the worst windstorm to hit Georgia since the Civil War.

"The Longest Yard" - 1974. Comedy. Burt Reynolds acquires the largest property in a new subdivision, then finds his plans to put up a huge antenna farm thwarted by a hostile homeowners association (Jackie Gleason, Loni Anderson, Dom DeLouise).

"The Lost Contest Weekend" - 1945. Drama. Ray Milland in a dramatic battle on 20 Meters for one elusive QSL.

"I Was a Teenage Novice" - 1957. Drama. A troubled teenager (Michael Landon) finds fun and excitement after getting a ham license.

"It Came from Radio Shack" - 1977. Horror. Bill Bixby tries to keep a computer called TRS-80 from taking over the world.

"Rear Window" - 1954. Suspense. Alfred Hitchcock did several marvelous films heavy on the subject of ham radio. In this movie, James Stewart plays a man confined to a wheelchair, determined to break the CC&R's and put up an end-fed wire antenna going out his apartment window - without the neighbors catching on. Grace Kelly and Thelma Ritter also star. Watch for Hitchcock's appearance over in Ross Bagdasarian's apartment.

"The Man Who Knew Too Much" - 1956. Suspense. James Stewart shows up at an FCC testing office for his ham license. What he doesn't know is, he's over-studied for it, and is smarter than the examiners, who force him into working for them! Watch for Hitchcock's appearance as someone taking a code test! See if you can figure out what he's sending!

"The Birds" - 1963. Thriller. The classic about a bunch of people stranded in a Northern California town who find that the only means of communication to the outside is by way of some of them newfangled OSCAR satellites.

Other Nominees:

"Frequency" - 2000. Drama. Ham operator finds his radio can time warp and talk to his dad decades in the past. How does he expect to QSL?

"Contact" - 1997. Drama. Female ham operator (Jodie Foster) controls the Arecibo radiotelescope, where she picks up an extraterrestrial signal. Now that's what I call DX



Friday, November 27, 2020

Tecsun PL880 Repair

 


 I was fortunate to pick up a broken Tecsun PL-880 for almost nothing. Here is the story and result.

 

Back Story

The radio was owned by a ham radio operator who used it as a bedside companion. He said that it fell off the nightstand one day and crashed on the floor. There was a Tecsun AN-48X antenna connected at the time and the crash damaged the connector. The owner attempted to repair the antenna jack using a home brew method. He said the radio never worked right afterwards. AM and Shortwave band reception was flaky and the tuning encoder wasn't working well either.

Here are some screen caps of a video he made about the radio.





 


Diagnosis/Repair

The radio arrived a week later and I put a fresh 18650 in. Powered up and tuned FM stations just fine. Switched to AM and shortwave - it was completely deaf. Normally the strongest AM station in town is able to come through on a crystal radio set, but not the Tecsun. The tuning knob was erratic and seemed to jump two steps or not do anything at all while tuning. Touching the tuning knob increased static to the radio.

A few ideas crossed my mind at this point. The radio suffered cracked solder joints or misalignment occurred from the crash. The front end transistors were blown or the repair failed.

 My first look inside the radio. Notice the compressed brown wire next to the screw hole. There was a nick in the insulation from the screw. (The back of the radio case has a metal shield and pad to ground the radio to the PCB shield.) Also noticed several missing screws.


 I removed the home brew connection and the broken  antenna connector, then installed a temporary jumper across the external antenna switch pads. Also cleaned up the solder flux and excess solder. I wanted to see if this was a simple fix.


I powered up the radio and it was still deaf on AM and shortwave bands, but the tuning encoder works great now (suspect ground short from previous owner's repair).

Time to figure out the radio circuitry and trace/test components. I used my DMM, signal generator, and scope to make my way through the receiver. Immediately, I found a cracked diode in the protection circuit next to the antenna jack, I replaced it with a 1N4148.

 


No other broken traces or failed transistors in the front end until I made my way to the mixer circuit and the signal died. I found a broken inductor on the board at L9. L9 is a .47uH fixed inductor that couples L6 to the mixer input for AM/SW. I cannibalized another receiver and replaced the component. Now the signal tracer was making it to Q7 and Q8!

I powered up the radio and tuned WWVH on shortwave. The radio came alive! Tested AM and it was very weak. Time to go back to the AM input circuit. Q26 tested fine, but the ferrite antenna leads needed to be reflowed as well as a broken wire repair at AM1.



Tested the radio and AM came back to life! Now on to the external antenna jack. I ordered replacement jacks and soldered one in.



Now the radio is as good as new! External and internal antennas work. I did not need to perform an alignment on the radio (The RF shields need to be desoldered).




73,

W9JES


Saturday, November 14, 2020

New Radio?

 Coming soon to the blog! We will perform some repairs and enhancements on this radio.. Stay tuned for more updates.




Friday, September 25, 2020

Live Shortwave Radio Chat on Zello

Remember the good old days of the IRC chatroom on SWL'ing Post? Well now there is a new way to network and discuss all thing shortwave!

Visit the SHORTWAVE AM LW channel on Zello.

 

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 $26. Shipping in the US is free.

 


 Speakers available for:

  • ATS-909
  • DX-398
  • 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.

Here is a bad speaker and the sound on a DX398.



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 Panadapter

This modification is similar to the DX390 panadapter tutorial that I posted HERE. I encourage you to check it out for more detailed information on panadapters, software, SDR dongles, and configuration.


What You Need

  • SDR


  • Female MCX bulkhead connector



  •  MCX male to SMA female cable
  • 24ga insulated copper wire
  • Additional cables or adapters to connect the SDR to your radio available on Amazon.
  • 1k ohm, 5 watt resistor
  • 1 nf to 2.2 nf non-polarized capacitor (I used a 2.2nf film capacitor)
  • Drill bits. Cordless drill
  • Soldering iron. Heat shrink tubing
  • SDR software
  • Drivers for your RTL-SDR

  

The Radio


The DX-398/ATS-909 is a dual conversion, superhetrodyne receiver.. 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 maximum bandwidth.


Connecting your SDR directly to the radio could alter the signal of the IF stages and cause poor reception. It could also transfer unwanted DC voltage between the radio and your SDR. We will use a small value capacitor for blocking spurious voltage and resistor to prevent receiver sensitivity drain. Connect them in series to your radio.


Identifying the correct tap point for a strong IF signal in this radio is fairly simple. We could tap between Q3 and Q4 near the filters. The Sangean service manual indicates TP11 is used to measure the 1st IF frequency. We can use this for our panadapter.



 

Connecting the Cable to the Radio

Disassemble the receiver case and remove the large circuit board. It is much easier to remove the speaker and control pcb before drilling holes and soldering. 

Drill your holes in the plastic case near the external antenna jack. Watch out for the two inductors. You can gently separate the rear pcb from the plastic housing to prevent damage to the components.

Make your cable assembly and add heat shrink.


 

Secure the cable assembly with the connector nut.




 Route the wire through the top hole and solder to TP11.


 

 Reassemble the radio and test.




73,

W9JES

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


  • 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.



  • Remove the copper section from the 4 plastic retaining posts

  • Using needle nose pliers, gently flatten the notch that sticks up on one side of the ring.

  •  
  • 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 +/- 3KHz
  • RF Sensitivity
    • Ability to pull in signals at 2% over the noise floor (this is subjective as some radios measure sensitivity in dBµ/m or µV/m)
    • 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

What is a Panadapter?

The next mod in this series is going to show you how to add a connection to your radio, connect to a SDR receiver, and use it as a panadapter!

A panadapter is a device that gives you a visual representation of the radio spectrum in a waterfall or line display and “captures" the audio from your radio at the same time using a low cost SDR unit.

Panadapters allow greater signal processing options surpassing some physical radio limitations. You can use an array of filters, decoders, demodulators, and other plugins to enhance your listening experience. Many high end receivers and amateur radio transceivers now offer an easy way to connect panadapters to your computer. You can also use the panadapter as a second audio processor/receiver by listening to two frequencies at the same time - one on the radio and one on the computer.


The benefits of using a panadapter are endless. You can get an idea of where activity is on your shortwave radio with a visual and wider view of the radio spectrum. 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.



I recommend the RTL-SDR Blog V3 which includes a temperature controlled oscillator to prevent drift. You can also use a generic DVB TV tuner for your radio.


What You Need

  • Female SMA cable with RG316 coax for the radio available on Amazon


  • Additional cables or adapters to connect the SDR to your radio also available on Amazon.
  • 1k ohm, 5 watt resistor
  • 1 nf to 2.2 nf non-polarized capacitor (I used a 2.2nf film capacitor)
  • ¼ inch drill bit. Cordless drill
  • Soldering iron. Heat shrink tubing
  • SDR software
  • Instructions and Drivers for your RTL-SDR

 

 

The Radio


The DX-390/ATS-818 is a dual conversion, superhetrodyne receiver. One thing that makes this radio great for modification is easy access to the 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 maximum bandwidth.
The second tuning coil (T2) was omitted in final production and we can use this for our IF tap.



Connecting your SDR directly to the radio could alter the signal of the IF stages and cause poor reception. It could also transfer unwanted DC voltage between the radio and your SDR. We will use a small value capacitor for blocking spurious voltage and resistor to prevent receiver sensitivity drain. Connect them in series to your radio.


Identifying the correct tap point for a strong IF signal in this radio is fairly simple. We could tap between T1 and T3 or the output of Q3 and Q4 and receive a strong signal. I decided to use the omitted T2 circuit where it connects to R39. 

 




Connecting the Cable to the Radio

Disassemble the receiver case and remove the large circuit board (Don’t forget to unsolder the speaker leads and disconnect the two cable sockets from the display board)

Carefully drill a ¼ inch hole into the side of the radio for the cable. The hole should be about 1 inch from the top of rear case and ½ inch from the back of the case.



 

 

Solder the resistor and capacitor together


Strip the braid and center conductor of the coax then solder the resistor side to the center conductor. Don’t forget heat shrink tubing.The cable assembly should be approximately 6 3/4 inches long from the inside edge of the connector to the solder joint at R39.


The braid was not needed to pick up the IF signal. It could induce noise to the SDR. You can install a ferrite choke over the coax cable if you have issues with noise.

Solder the capacitor side of the cable to the hole next to D10 as shown. Then route the cable across the board and secure with tape.

 




Carefully reattach the board to the radio and route the coax cable through the hole in the case.

 


Reassemble the radio and test for normal operation.

 

Setup the HDSDR Software

There are many videos on YouTube and articles on RTL-SDR Blog to help you get started. I highly recommend them if you run into issues with the SDR or software.

Connect your SDR to the computer. Install and Run the HDSDR software. Select the SDR you want to use. 

Configure the bandwidth and AGC settings as shown in HDSDR. Choose 2400 kbps for the sample rate (if using a generic SDR or RTL-SDR).

 



Setup your receiver in the RF Front End configuration menu. Select SDR Hardware on Down/Up-Converter LO Frequency.. Add the IF frequency plus the frequency displayed on the radio in the box shown. Make sure to convert everything into Hertz as shown below.

For example: If your radio frequency is 4.000 MHz.

4 * 1,000,000 = 4000000

4000000 + 55845000 = 59845000

Type 59845000 in the box and click Apply. Don't forget to change this value if you change the radio frequency!



After connecting all cables, plugging in the SDR receiver, and running software; turn on the radio, set the frequency you chose above, and adjust the RF gain as appropriate. Tone, Volume, BFO, Narrow/Wide controls on the radio doesn’t affect the signal to HDSDR. You can set those to your preference. You will be able to tune anywhere from 150Hz to 29.999MHz in HDSDR.


Setup the SDR# Software

There are many videos on YouTube and articles on RTL-SDR Blog to help you get started. I highly recommend them if you run into issues with the SDR or software.

  Setup your receiver in the device configuration menu. Click the gear and make sure Quadrature Sampling is selected. Adjust the Gain as desired.



On the main screen, find the source section for your SDR. Check the Shift box. Add the IF frequency plus the frequency displayed on the radio in the box shown. Make sure to convert everything into Hertz.



For example: If your radio frequency is 4.000 MHz.

4 * 1,000,000 = 4000000

4000000 + 55845000 = 59845000

The shift frequency must be a negative value. Type -59845000 in the box and click Apply. Don't forget to change this value if you change the radio frequency!

 





73,
Jesse W9JES