Grass Cutting Headset

[rwanttaja]

Considering it was designed to be used specifically with aviation headsets and has the customer reviews from pilots of old ragwings to support it, I would NOT say it would work better with a walmart headset.

Whether a headset with a mismatched impedance is adequate or not depends on the user. I had a Flightcom ANR headset in my Fly Baby for years (Icom radio). Worked OK. As the years went on, the radio seemed to be getting quieter. My hearing going? My headset deteriorating? Either was possible.

But adding a $3 Radio Shack transformer as an impedance matcher brought the volume back up again.

Sure, those guys in ragwings might be happy with the straight headset. But they might be happier if they tried it with an impedance matcher. I fly one of them old ragwings, and am sure happier with my 8 ohm speakers or my impedance matcher.

The neat thing is, this is easy (and cheap!) enough to test. Connect your aviation headset to the radio, lay the headset on the bench, turn on the radio, tune to an unused frequency, then turn up the squelch so you get a constant hiss. Then disconnect the aviation headset and plug in your commercial one. In my experience, the higher volume level with the commercial headset is immediately apparent.

My winter headset is a Rapid Radios aviation headset that I modified by replacing the 300 ohm speakers with 8 ohm units.

Using lower ohm speakers will boost volume, but that's because they draw excessive power from the amp.

No, I'm sorry... they draw MORE power from the amp (lower resistance!) but not "excessive" power. The specs for the Sporty PJ2 say:

"Audio Output
350 mW into 8 Ohms, 10%"

It's *designed* to put a given power level into an 8 ohm load. That is not "excessive."

Let's assume the radio is limited to 350 mW output. With an 8 ohm speaker attached, that's roughly 0.20 amps of current. With a 150 ohm speaker attached, that's 0.05 amps...a quarter of the current. The higher impedance speakers are going to have a harder time converting current to sound.

Could even be a typo in the manual from the real manufacturer that's used to building 8 ohm radios, or just a measurement standard like how 48 watts can be 12v@4a or 24v@2a.

I'd have to have more evidence before assuming the published specs are incorrect.

In any case, I doubt that *any* of these radios were designed from scratch. Little VHF radios are sold for a variety of purposes, and it's probably a minor change to put them into the aircraft band. In the old days, we'd just use a different set of crystals, but no doubt the kids have better ways of doing it.

But it gets thornier when you reach the last stage of audio output. Every one of these radios has a speaker installed, and I'd be very, VERY surprised if they were anything but the 8 ohm units used in the Ham, police, and other VHF comm units sold by the company.

So...if the same radio is also to be used with an 150 ohm aviation headset, it needs impedance matching. The question is whether the PJ2 includes a SEPARATE impedance matching section to handle the 1/4" output jack. I kind of doubt it, but I could be wrong.

Just tested the adaptors for my ICOM ICA5 and IC23 radios. No sign of any internal circuitry... infinite resistance between the shell and the tip, and no resistance on any line from the plug at one end to the jack at the other. There's no impedance matching included. I really doubt other manufacturer's adaptors are any different.

In any case...again, it's easy to do a sound test between the two types of headsets. Don't have to believe me....

Ron Wanttaja

[lnuss]

By searching for "icom aviation headset adapter" (without the quotes) you can find an adapter designed to take care of the aviation vs non-aviation level/impedance problems when using your David Clarks, etc. Amazon, Sporty's, Aircraft Spruce and others carry them. I use one with my Icom A-21 and David Clarks and it works great.

[CHICAGORANDY]

I'm SO dumb - I read the post title and thought that's an insane way to try and mow a lawn, with blades on your head.

[rwanttaja]

By searching for "icom aviation headset adapter" (without the quotes) you can find an adapter designed to take care of the aviation vs non-aviation level/impedance problems when using your David Clarks, etc. Amazon, Sporty's, Aircraft Spruce and others carry them. I use one with my Icom A-21 and David Clarks and it works great.

I looked at several of the ads that came up, and saw no mention of impedance matching. Can you point me to an ad that does?

The transformers that I've used for impedance matching are about the size of a large sugar cube...all the adaptors I saw didn't seem to have room for one, internally. The companies could have custom transformers made, but that would be a pretty small production run.

Ron Wanttaja

[lnuss]

I looked at several of the ads that came up, and saw no mention of impedance matching. Can you point me to an ad that does?

The transformers that I've used for impedance matching are about the size of a large sugar cube...all the adaptors I saw didn't seem to have room for one, internally. The companies could have custom transformers made, but that would be a pretty small production run.

Ron Wanttaja

Nope, can't find anything about specs for those -- good point. So I went to check out my adapter and I'd forgotten that it was a different animal, an Icom HS-61 Switch Box, according to the label, and it incorporates all the needed pieces including plugs for the headset, a push-to-talk switch, a nice coiled cord with adapter plug to fit my IC-A21, and even has adjustments for mic gain and monitor gain. Of course you get sidetone on transmit, too. Anyway, it works well, even in a Super Cub cockpit.

Sorry for being misleading, but I guess that's what I get for depending on memory. Of course there are non-transformer ways of matching impedance, which would potentially be smaller and could still be powered from the voltage on the mic jack, if the radio provides it, but if it's not a single chip it could get expensive.

Addendum: I just found this unit at Sporty's. It's aimed a using a headset with a PC, but might work -- includes a small box and needs a 9V battery -- but I still can't find specs: https://www.sportys.com/general-avia...t-adapter.html

[rwanttaja]

Nope, can't find anything about specs for those -- good point. So I went to check out my adapter and I'd forgotten that it was a different animal, an Icom HS-61 Switch Box, according to the label, and it incorporates all the needed pieces including plugs for the headset, a push-to-talk switch, a nice coiled cord with adapter plug to fit my IC-A21, and even has adjustments for mic gain and monitor gain. Of course you get sidetone on transmit, too. Anyway, it works well, even in a Super Cub cockpit.

Sorry for being misleading, but I guess that's what I get for depending on memory. Of course there are non-transformer ways of matching impedance, which would potentially be smaller and could still be powered from the voltage on the mic jack, if the radio provides it, but if it's not a single chip it could get expensive.

No problem, conceivably your switch box might include something for impedance matching.

I checked mine by first measuring the resistance between the two leads for the headset. Infinite resistance indicates that there's no transformer across the leads.

I've heard some folks handle the mismatch by installing small resistances (50-100 ohm) in line. I checked mine by measuring the resistance of each line from the plug to the jack. Zero resistance indicates there's no added resistance.

Folks should understand... I don't doubt that some folks get acceptable performance without an impedance matcher. Probably a combination of type of handheld, age and condition of the headset, their own hearing capability, and the sound level inside the aircraft.

I measured 105 dB at chest level in my Fly Baby. That's considered to be dangerous if exposed for more than a half hour. Since my second :-) flight in the aircraft, I've used hearing protection (including when I was flying NORDO). In my case, it's just too much for a handheld radio and a stock aviation headset to overcome.

If you're NOT having a problem...don't worry about it. But I have heard from a number of folks, thanking me for posting the information and reporting a great improvement in their volume. I've built a number of adaptors and "lent" them to folks... 'lent' in the fact that I haven't got them back, yet. One guy was so impressed, he's put the adaptors into production...

https://qhaviation.company.site/Impe...ter-p291255055

Remember, PASSIVE noise attenuation is a very good thing...which might be a good reason to NOT use a consumer-grade headset since their passive noise reduction isn't very good.

In short, your headset works fine with your handheld: Great! Having trouble hearing your handheld? Consider getting/building an impedance adaptor or try using 8-ohm Plugfones.

Ron Wanttaja