SFI > 250 or bust!

My old headset is totally worn out. In fact its second life started in 2000 when I salvaged some professional intercom headsets from the scrap bin and combined the parts into one new working item. I was amazed to learn that the default microphone element could be replaced a Heil HC4 capsule. Same size, same connections. Since that day I had a good headset for the price of the HC4 mic element I bought as a separate item. Even though I don’t use it often and when I do it’s with care, it is worn out after 15 years. I only use it three or four times a year in a phone contest and never wear it for CW. Electrically all is fine but the ear pads are gone, inside the foam padding is starting to disintegrate etc. Time for a new one!

I never liked the classic Heil models. Too light, too flimsy, too expensive. Last year I promoted the new model but Bob Heil didn’t send me one on trial. Would have given him free promotion though. Exposure on my blog is priceless after all. This model 7 is pricey but if it’s worth it… However the eHAM review section showed quite a few negative comments about DOA and poor QC.

On the other hand Germany’s biggest reseller had a new brand on stock. The Arlan Communications products. eHAM showed almost unanimous positive comments. And it looked really heavy duty. With supposedly a lot of suppression of the noise in the shack from amp fans etc. So I bought one and ordered the extra cable to fit the microHAM MK2R+. Delivery was fast and the darn thing was one helluva headset. I liked the cable. It felt ‘siliconishly smooth’ and looked nice. Although I find 75 Euro a lot for such a cable. I put my foot down: my cable guy days are over – or at least I thought.

When I finally got around testing it on the MK2R+, initial disappointment made soon way for sheer frustration. It didn’t work. Not by far. The VOX didn’t work, monitored audio was distorted, I heard a lot of jet engine sounding noises and audio feedback. Interesting side note: the date was one week before CQ WW SSB.

I sent a mail to both microHAM support guru W4TV and to Arlan Comms. The Arlan company owner was very quick to reply (thumbs up!). He pointed out that the dynamic microphone element has a low impedance of 200 ohm and that the MK2R+ stuff probably didn’t like that. Could be as the Heil HC4 as 2k impedance if I’m not mistaken. I envisioned the classic theoretical amp model: infinite Z in, zero Z out. Would the microHAM input circuits be that low in impedance that it could not handle 200Ω?

He continued that most of his customers using microHAM stuff used the electret microphone. And that the K3 by itself didn’t have a problem with the dynamic element. I plugged the headset straight into one of my K3s and sure enough: it worked. I could order a new microphone element but that would be yet another extra 50-60 Euro and would leave me with a useless dynamic mic capsule. Needless to say, I was getting pretty P.O. It was now Monday before WW SSB…

I got a reply from a two happy users of the Arlan headset with the microHAM stuff. So it should work here too. Then W4TV of microHAM stepped in. Bottom line: all Arlan Communications said was wrong and he gave some info about mic and headphone circuits that I actually knew from my previous life as a broadcast tech. However when buying a cable that costs 75 Euro I expect that cable to work. I quit building my own cables because of lack of time and being through with soldering cables. My co-workers didn’t call me The Cable Guy for nothing fifteen years ago! Actually this is the second time I buy an expensive faulty cable that I should have made myself. At least Elecraft had the courtesy to refund the bad cable admitting there had been a few faulty ones in the past.

I sent another mail to Arlan asking for the pin out color code of the plug. Until now I have yet to receive an answer. So with less than four days to WW CW, reverse engineering was the way to go. I opened up the cable and started tracing wires and measuring resistances. Sure enough the mic return lead was soldered together with the shield of the cable and bound to the shield of the earphone speakers which was in turn soldered to GND. Once I unsoldered and cut that lead, everything suddenly started working like a charm. Oh boy, all the time wasted debugging and writing mails… I could have soldered ten of these cables back when I could still solder interface cables with my fingers in my nose. The only thing left to do was reverse left and right channel on the cable. I don’t see that as a big problem because my CW headset has the same problem. But a normal headphone can be put on the head in reversed position, a headset not. Purists will say that actually you can but then the mic would be on the back of your head.

All is well that ends well. Two thousand SSB contacts in WW SSB with good audio reports when asked. The headphone does not play in the feather weight category nor is it light on the head. I consider that a tradeoff between poor mechanical quality and letting ambient noise through versus this one. It seems to be strong. The brace is mostly made of metal parts and removable thus washable padding. And actual little bolts and nuts. The headphone shuts off the amp blower noise completely and I don’t hear anyone coming into the shack. Except my two little boys when they rush in and trip VOX. So except for the poor electrical design of the cable, I’m pretty happy so far. I must say that the look and feel of the cable is first class.

During WW SSB an active Belgian contester who had followed the messages on the microHAM list sent me a mail. He had been a happy user of the headset for a few years but now he ordered a new cable for a second rig and had trouble getting it to work. He asked what my solution was. Turns out his cable had the mic return / GND problem too! So people buying an Arlan Communications interface cable to go with microHAM interfaces: BEWARE and fire up the soldering iron.

2 Responses to New headset

  • FYI … I bought the second headset with an M350ADJ electret mic, which is not the best one for the TenTec Orion. Thought that since I would be hooking this up to a Microham MKII this would leave me with 2 identical and interchangeable headset (as the other TRX is an Icom 7800). Bad decision to be honest, should have gotten the M207 Dynamic for the TT.

    Then the interface cable I bought was one for connecting to the EXT MIC (front panel) of the MKII … bad decision 2, only from looking at the setup (duh … what WAS I thinking when I ordered that cable!? … I don’t drink alcohol so that leaves only a low caffeine level) … having a cable dangling out of the MKII in the front when all other cables are hooked up to the back is a no go basically. So then I got the cable for hooking the headset to the rear of the MKII (with the supplied RJ45 to TenTec 4 pin Foster). After rearranging the jumpers inside the MKII, everything worked as it should. Audio (also recording with N1MM+) is good … nevertheless this whole Window audio setup is a pain in the ass and I wonder if there is anyone that gets this working without the try and error method.

    Just had RFI which I solved with 4 turns through a purple toroid on the phones output of the Orion.

    By the way: I can not confirm the non responsiveness from Dave WI6R! He always responds quickly to my e-mails. When he is on the road it might take a couple of hours longer but he’ll respond from his mobile phone.

    • Hi Frank, tnx fr comment.

      In the mean time I bought the RadioSports plain headphones too. Since I only use a mic’ed headset a few times a year, I might as well use the one without the mic most of the time. It’s expensive but it looks long-lasting so I hope I won’t regret it and that looks are not deceiving in this case.
      Some people might find it too heavy and too tight on the ears. But I don’t mind that since it effectively blocks all noises from the outside world. It’s so good that last weekend I thought my amp’s blower’s bearings suddenly were worn out and making a helluva noise, while in fact it was the neighbor’s heavy horticulture engine puffing away about 15m from the open shack window.

      Years back, when I used my lightweight open headphones in WAECW, I had to keep the window closed as the harvesting machines where coming for the wheat and straw bales. It was almost always around the WAECW weekend. I liked those headphones a lot but they let all sounds and noises pass through. If those heavy machines constantly roar around the QTH, it’s hard to copy weak QTC. Then I changed to another brand of amp that has a very loud blower so I was forced to find a noise blocking type of headset.

      RadioSports’ Dave was very responsive to the initial problem, trying to sell me an electret mic element and pointing a finger to microHAM. But he was far less responsive when I asked for the wire color scheme to fix the issue. To find out it was in fact a problem in the expensive cable they supplied.

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