Friday, April 10, 2020

UPDATE #2 - 'Poor Hams' Wooden Antenna Mast

This past winter right after the RAC Winter Contest an ice storm built up too much weight on my Off Center Fed Dipole antenna and the top 4 feet of my trusty wooden antenna mast snapped off.

Jump to Easter weekend about 3 months later, enough snow has melted that I convinced my wife and daughter to help me bring down the tilt over wood tower and reattach my OCF antenna to the top of the mast.

It was one of those activities where no one had the idea of stopping and taking a few pictures so I only have a few snaps of when the work was finished. Thanks to Curtis my neighbor for lending a hand as well.

After we were done I ran back inside the shack and quickly tuned a few spots on all the HF bands and everything is back to normal. So glad I can get back onto more of the HF bands again.

Note: I've always suspected that the top 4 feet of the original mast design would be the point most likely to fail and I was right. But it stood for 8 years before snapping in that winter ice storm. Today the antenna tilted back over exactly as designed and was not difficult work for the 4 of us involved, there was no real repair done as all I did was reattach the antenna to the new high point of the wooden mast and lifted it back up.

At the bottom is a modified copy of the build sheet I did 8 years ago when the antenna mast was first built. It notes the spot where the top section of the mast broke off in a winter storm. My suggestion now, shorten or remove this top section of the mast.

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 life 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 post about these here on the blog.

Heil Pro-7 Specs (headphone portion)
  • Stereo
  • Impedance - 32 Ohms (Thanks for the confirmation by Steve Warford from Heil Sound)
  • 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.