Saturday, April 04, 2020

Headphones for Ham Radio

I have a problem, an addiction really.
Hi, my name is Aaren and I'm a headphone addict.

Years ago when I was young, single and had lots of dispensible income I got into high-end audio (Hi-Fi). My stereo equipment and loudspeakers were audiophile-grade and my music collection was measured in the 1000+ range.

Many years later I'm married with a teenager, we have a mortgage, a camper, multiple vehicles and my dispensable cash is now invisible cash.

In my audio hobby, I transitioned from spending thousands on speakers or amps to spending hundreds on headphones and headphone tube amps. I can venture to say the quality of my sound experience did not change, and my family and neighbors are now pleasantly left out of the experience as I quietly enjoy my music.

Purchasing and enjoying different makes and models of hi-fi and studio-grade headphones has become another one of my vices. This includes headphones from premium brands like Focal from France & Beyerdynamic from Germany.

Then my amateur radio hobby comes along about 8 years ago and the sonic experience is entirely different. Instead of the pure clean audio that I experience with my music, I now have noise and hiss and static filling the speakers or headphones with the challenge of pulling those weak signals out of the air.

Hence my recent interest headphones designed for radio.

Typically as humans, we can hear in the range of frequencies from 20 Hz to 20,000 Hz. This range is known as the audio range.

The traditional audio frequency range of standard telephone transmissions was roughly 300 - 3400 Hz, a much much narrower range for just human voice communications.

For comparison here are some basic specs from a couple pairs of my music/studio-grade headphones

Focal Spirit Classic

  • Stereo
  • Impedance - 32 Ohms
  • Frequency response 5 Hz - 22,000 Hz

Beyerdynamic DT990Pro

  • Stereo
  • Impedance - 250 Ohms
  • Frequency response 5 Hz - 35,000 Hz

Heil Sound Pro-7 Headset

A couple years ago I bought my first boomset/headset (headphones with a microphone) designed for ham radio from Heil Sound. Bob Heil is famous in two sectors of his life's work, his professional studio and live touring equipment for musicians, and his long love for the hobby of amateur radio. Bob's company specializes in equipment for both sectors of the market. And his equipment is very well respected in both.

The Heil Pro-7 headset that I purchased had the following listening specs. And I wrote a more detailed blog post about these here on the blog.

Heil Pro-7 Specs (headphone portion)
  • Stereo
  • Impedance - 30 Ohms (my best guess from online research but it was hard info to find)
  • Frequency response 100 Hz - 12,000 Hz
Notice that the Heil Pro 7 headphone speakers respond from 100 Hz through 12,000 Hz before attenuating way down at the lower and higher ends of the spectrum. Music audiophiles want speakers that go lower and higher in order to hear the lower and higher notes, but for amateur radio and shortwave, these headphone speakers focus on the CW, SSB, AM, FM human voice range that we want and need to hear. Having a higher response often means static or hiss can be emphasized and we don't want to hear that. Bob's design gives you a clean flat response in only the range you need to hear and eliminates the range of sounds that you don't need to want to hear.

Kenwood HS-5 Mono Headphones

My latest purchases are interesting as well and I very much enjoyed the research before the purchase.

I had no idea Kenwood made ham radio/shortwave related headphones as well. I can't tell if these are retro-styled or if Kenwood has seen no reason to update the design and they're actually a 20-year-old trusted and true model?


Kenwood HS-5 Specs
  • Mono (YES, many many radios especially older ones are mono only)
  • Impedance - 8 Ohms 
  • Frequency response 150 Hz - 4,000 Hz

The Marketing Blurb
Kenwood Communications Headphones are perfect for amateur radio and shortwave listening. They feature cushioned foam or vinyl earpieces that make listening so comfortable, you'll forget you're wearing them. Drawing from Kenwood's extensive audio background, their high-performance Kenwood driver units reproduce communication sounds for signals that never sounded so clear! Their audio response makes them great for all modes; CW, SSB, FM, and AM. Kenwood Communications Headphones provide excellent speech fidelity and their lightweight allows for extreme comfort while listening for hours.

These Kenwood HS-5 mono headphones are engineered and tuned strictly for radio communication purposes to provide distinctive voice sound (150-4000 Hz -6 dB). I can't wait for these to arrive and try out. So often in the radio hobby, we grab a pair for 'regular' headphones or ear buds and get to work. But by engineering the lowest and highest sounds out of the equation so much noise can be removed without the need for filters or DSP.

They are supplied with removable foam-type ear pads. They are also supplied with a second set of leatherette pads with a cavity in the center. It is easy to change the pads.

With ¼ inch, mono plug and 6.6 foot (2m) non-coiled fabric wrapped cord.

Heil Sound Pro Set 3 Headphones

First off these are not dedicated radio headphones like the Kenwood HS-5's, instead Heil Sound has designed a more well rounded and versatile pair of headphones.

The Marketing blurb

The Heil ProSet3 professional stereo headphones have been designed for a wide variety of applications including amateur radio, studio recording, commercial broadcast use, and casual listening. With a frequency response of 10 Hz to 22 kHz, they deliver exceptional articulation and clarity, with beautiful sonic accuracy in a closed-back, lightweight headset The over-ear headphones weigh only 7 oz and feature padded ear cups so that they will be comfortable and non-fatiguing over long periods of time.

For ham radio operators and listeners, the exclusive Heil Phase Reversal switch allows the user to move the signal acoustically, which creates a spatial widening of the sound field that makes it easier to ‘see’ a signal inside a pileup while removing listener fatigue during prolonged use.

To accommodate different listening situations, the headphones come included with three detachable cables: a 5.9′ flexible straight cable with a 1/8″ headphone plug, a 5.9′ straight cable with an iPhone and iPod compatible 1/8″ plug, and a 9.8′ coiled cable with a 1/8″ headphone plug. The cables have twist-lock terminating 1/8″ gold-plated connectors. A 1/4″ gold plated screw-on adapter comes included with the headphones.

Heil Pro Set 3
  • Stereo
  • Impedance - 32 ohms
  • Frequency response - 10 Hz - 22,000 Hz
As you can see from the product description and the specs these are basically studio-grade stereo headphones which one ham radio feature 'the phase switch'. The frequency response is very similar to high-end audio headphones so you can expect to hear a more full range of sounds including the hiss from the higher frequencies. But you can use these stereo headphones for everything and expect to hear great sound no matter what the purpose is.

The phase reversal switch is a unique feature though. As an owner of the Heil Pro-7's which also includes this feature, it is a feature worth considering. The way the switch works if by flipping a two-position switch you can change between being in phase and out of phase. This can greatly help the listener "dig out" weak signals. The phase reversal is used to acoustically 'move' the signal from front to back. Reversing the phase creates a spatial widening of the sound field making it easier to 'see' a radio signal in a pileup as well as removing listening fatigue.

Wrap Up

In conclusion, this is just a summary of some of the higher-end headphone solutions available for amateur radio and shortwave listening. Please keep in mind that both Kenwood and Heil make other lower-priced models so you have a larger variety of products and prices to work with. I've focused this blog post on the highest level models from each brand because these are the units that I own or have researched and ordered.


Thursday, February 27, 2020

MMDVM Duplex Hotspot

 MMDVM HS Dual Hat Duplex Hotspot

  • with Raspberry Pi Zero W
  • larger 3.2" LCD
  • 16G SD Card
  • Metal Case

Version 1.3 firmware
Revision 1.3 board

Crystal Oscillator - ECS-TXO-3225-147.4-TR
High-Performance Narrowband ISM Transceiver IC - ADF7021

This PCB uses the MMDVM HS. It has two ADF7021 onboard and allows for duplex operation with two-time slots on DMR.

- A high-performance 32-bit ARM processor
- Fully tested
- Supports DMR, P-25, D-Star and System Fusion
- Onboard LEDs to show status (Tx,Rx,PTT, Mode)
- Up to 10mW RF power
- SMA antenna connector, Antennas included
- Mounts cleanly on all current Raspberry Pi's including the Pi Zero
- The firmware is pre-loaded and is easily upgraded via software.
- UHF 430-450 MHz,433mhz and 900MHz
- VHF 144 220 MHz

The upper antenna is TX, the lower is the RX antenna.
UHF+VHF SMA antennas
Modem select:STM32_HS_GPIO
Set TX frequency, RX frequency
TX, RX frequency had better 10M or more apart.
SLOT1, SLOT2 support.

Package included the fully assembled items including the below parts

  • MMDVM duplex HotSPOT Module (x1)
  • Raspberry pi zero w (x1)
  • 16G SD card (programmed with PI-STAR)
  • Antenna (x2)
  • Black case (x1)
  • 3.2" LCD (x1) 

Friday, January 17, 2020

A Night of Yaesu Upgrades

It all started with a programming change. All I wanted to do was add a couple new memory channels into the FTM-400DR. For some unknown reason, the two versions of the radios admin software would not download the current settings from the radio to the PC.

After some browsing online I saw others mentioning that the radios need the latest firmware to work with the latest programming software. I had updated both radios a year ago but since then Yaesu released the C4FM DG-ID features sometime in the last year.

Well if it wasn't a ton of work with lots of steps that took me about 3-4 hours from start to finish.

The FTM-400DR had to have the cover removed and a tiny switch flipped. Two different firmware updates each with their own utility and instructions. The two updates were DSP and main firmware.

The FTM-100DR had three updates. No cover radio disassembly was required this time but two hidden switches had to be uncovered and changed. All three updates also had their own utility and instructions. The three updates were DSP, main, and panel firmware.

The good news after all the radio work the memory changes I wanted to make from the beginning finally worked.

Now I can go to bed.

Wednesday, January 15, 2020

A Personally Hosted Cloud File Solution

I understand that not everyone has the knowledge or equipment to host servers at home. But for those that do this is a great solution that I settled on after testing a few different ones.

Yes, you can get free or paid cloud file storage from DropBox, OneDrive, GoogleDrive, etc. But I often talk to people concerned that these solutions are holding your personal and important data files in exchange for some kind of loss of personal privacy. Well if you are concerned about that you can deploy your own personal cloud storage solution at home.

I used a VMWare appliance for OwnCloud personal edition. This is the free version of the product with fewer features than the Enterprise version that customers must buy or subscribe too.

The appliance is the easiest way to get ownCloud up and running and is best for non-technical users. It is built on UCS ("Univention Corporate Server") and is fully set up and configured with a secure connection and the ownCloud Proxy app. You can install this on VirtualBox or VMWare which are software virtualization platforms that run as an app on your PC or can be installed on a dedicated server like I have at home, you download their OVA file and load it up. Appliance installation instructions are provided in the documentation, it's not that difficult to install.

Once installed you have an Administrator account to login and start configuring the system. The appliance will store your data within as long as your host system has the room accommodate the growth of the virtual machine appliance, but I opted to configure External Storage as I have a Drobo device where most of my home data is already stored. By linking this network storage to the OwnCloud server I now have access to all the files I want to share via my personal cloud. You can and should be selective on what data you share in your personal cloud. I configured certain folders on the Drobo to be seen by ownCloud, but not all of my files and folders.

Keep in mind that one of the true benefits of cloud storage services like DropBox and the others is that your data is located in a cloud location offsite from your home. This can be an excellent backup solution.

If you are hosting your own cloud, you lose this offsite backup. Your data hasn't moved anywhere or been copied to somewhere else. This is just a private was of accessing your data from anywhere using the built-in website or the desktop client software for Windows, Mac, Linux, iOS, and Android. You still need to backup your data at home in some other method.

Tuesday, January 14, 2020

My new SDR - the RSP1A from SDRplay


SDRplay is a UK based designer and manufacturer of very well made SDR receivers (IMHO).

The RSP1A is a second generation of their RSP1 entry level model which retails for about $150 in Canada.

The specs

The RSP1A is our new improved entry-level receiver—it is a powerful wideband full featured 14 bit SDR and perfect as an all round general coverage communications receiver plus much much more.  The RSP1A covers the complete radio spectrum from 1kHz (VLF) to 2GHz (Microwaves) with up to a massive 10MHz of visible bandwidth. With the companion SDRuno software which has all the popular ham bands and shortwave broadcast bands as “presets” for instant set-up. 
  • Covers all frequencies from 1kHz through LF, MW, HF, VHF, UHF and L-band to 2GHz, with no gaps
  • Excellent dynamic range for challenging reception conditions 
  • Low levels of spurious responses
  • Works with all the popular SDR software (including HDSDR, SDR Console, Cubic SDR and SDRuno)
  • ExtIO based plugin available
  • Software upgradeable for future standards
  • Strong and growing software support network
  • API provided to allow demodulator or application development
  • Multiplatform driver and API support including Windows, Linux, Mac, Android and Raspberry Pi 2/3 
  • Up to 16 individual receivers in any 10MHz slice of spectrum using SDRuno
  • Calibrated S meter and power measurements with SDRuno 
  • Ideal for monitoring of ISM/ IoT/ Telemetry bands <2ghz span="">
  • Ideal for portable operation 
  • Continuous coverage from 1kHz to 2GHz
  • Up to 10MHz visible bandwidth
  • Powers over the USB cable with a simple type B socket 
  • 4-bit ADC silicon technology (not another 8 bit dongle!)
  • 11 high-selectivity, built in front-end preselection filters
  • Software selectable AM/FM and DAB broadcast band notch filters
  • Software selectable multi-level Low Noise Preamplifier
  • Bias -T power supply for powering antenna-mounted LNA
  • RF shielding layer inside case
  • SDRunoWorld Class SDR software for Windows 
  • Documented API for new apps development 
  • Single SMA antenna socket covering entire frequency range

The most amazing feature in this receiver is that massive range. One receiver that can listen from;
  • LF (2200 meter band)
  • MF (630 and 160 meters)
  • HF (80, 60, 40, 30, 20, 17, 15, 12, 10 meters)
  • VHF (6, 4, 2, 1.25 meters, then 70, 33, and 23 centimeters)
  • The only Amateur Radio band this receiver cannot reach (that I might care about) is the 13 centimeter Microwave band which is 2300–2310 MHz (lower segment), 2390–2450 MHz (upper segment)
The unit comes with a very well thought out software package called SDRuno. While this software looks intimidating when you first load it up, I found excellent online tutorial videos from various sources that explained everything I need to get started. After that I figured things out by trial and error over an evening or two.

My antenna of choice getting started with this SDR was a super discone from AOR already mounted high on my small tower. While this is built for the higher frequencies (10m - 13cm), I was amazed to hear low HF transmissions as well. A different and better antenna (or two) may be in the plans for the future.