Friday, September 22, 2017

Apartment Antenna for the High Bands

Here is a look at a simple multi-band capable antenna design for people in an apartment or HOA that are able to snake a pole out the window for temporary operation:

Click to Expand

Monday, September 4, 2017

Koss SB-45 Headset and Sample Receive Audio

Koss SB-45 Communications Headset (click to expand)

Earlier, I posted a review of the IRIVER IGH-L20 headset for Ham radio use -- a good performing bargain headset.  A number of people expressed their sadness that IRIVER headset is only for sale in Asia, and has to be imported to other countries.  Wouldn't it be better to post a review of a headset that is both inexpensive and easy to find in countries like the USA?

Here's one for your consideration:  The Koss SB-45.

View into the earcup
The Koss SB-45 is sold for about $25 plus shipping on Amazon, and some Wal-Mart stores.  It is said to be a rebranded/slightly modified version of the Yamaha cm500, which gets incredible reviews from users on Eham.  You can read reviews of both headsets, and you'll see comments about how they're considered sounding identical and interchangeable at a contesting station.  I did notice, however, that Koss also sells an SB-40 version which looks more like the Yamaha cm500, but contains a dynamic mic.  The SB-45 reviewed here is the condenser mic version, which works with ICOM radios (the dynamic probably will too, but likely would require high mic gain settings). The Koss SB-40 and SB-45 look different, to me.  This makes me wonder how similar the SB-45 is to the more expensive, and highly-regarded Yamaha cm500.  I don't own the cm500, so I do not know.

I will say that the Koss SB-45 appears to be a good ham value, for the price.

1.  Very comfortable headset, even with long-term use.
2.  Generally very nice build quality (thin cord an exception)
3.  Attractive
4.  Adjustable microphone
5.  Very clear audio for DX sound
6.  Perfect weight
7.  No problems wearing with glasses
8.  Excellent outside noise blocking, but not overly so

1.  Thin cable
2.  Had same earpad material on my Sony headphones, and it began flaking severely within 2 years.  Radiosport material socks can fit over to extend life.
3.  Microphone lacks much bass.  My Icom 7300 settings are Bass +5, Treble 0.
4.  Receive sound is a bit bright, but very clear
5.  Need to remove wind screen and add a few layers of electrical tape to back of mic to remove room noise.  This is a :30 second fix, and highly recommended.

When I first purchased the Koss SB-45, I have to say I was a bit disappointed.  I felt they were far too bright on RX, and accentuated background HISS too much.  I am happy to say that I have since found a sweet-spot for listening, with the SB-45's.  These are some very sensitive headphones!  After a few weeks of use, I learned that I simply needed to adjust my ICOM 7300's bandwidth filtering a little to trim the highs, and to turn the AF GAIN/volume down (not a bad thing, given how headphones often damage hearing over time).  I live at a very noisy QTH, the noise can get to me. Radios tend to attenuate the hiss/highs a bit, with the volume down, and I find these headphones still allow the voices to come through clearly, after that AF Gain is lowered.  In the end, I'm pretty happy with the purchase.

8-Pin MIC/Headset Adapter HS-01C for ICOM 
The electret microphone of the Koss SB-45 is also extremely clear.  It's one negative, in my opinion, is that it lacks in bass, and that you need to remove the foam wind screen and add a few layersvof electrical tape covering the back side hole of the mic (easy).  Without doing that, you pick up more room noise.  What you get in return after this :30 second fix, however, is crystal-clear mid and high-level audio.  I found that some EQ-ing was in order, but reports have been pretty incredible with the ICOM 7300's transmit bandwidth set to my adjustments of WIDE 100-2900, or  MID 300-2900.  I've never been a fan of ICOM's jump to 500hz as the next choice on the bottom end for the NARROW setting, so I rarely use it.

My last article also left some people confused as to how you get headphones like this to work with the ICOM 7300, or other radios.  The trick is to search Ebay for your radio, and look for "headset patch cable" or something similar in the search string.  If you are wanting to buy this headset for the ICOM 7300, and need a patch cable, HEIL makes them.  I suggest you contact Bob Heil through his site, or use his website to determine which patch cable is right for you.  I added a photo of the one I purchased on E-bay, from K6VHF, for about $15 plus shipping, which I found to be cheaper.  It works well, and I have no issues with stray RF.  You can also build your own.  I will provide pin-outs for that in the following graphic, but if you use a dynamic mic, you need a 1uF non-polarized tantalum capacitor in series with mic lead.  This is according to Bob Heil, who also said you can get by with a .68F or a .47uF, but anything less will not pass good speech.  You don't want the blocking cap for an electret mic, however :

Sony earcups after 2 years
Link to Bob Heil's info on the Icom 7300 and mics:

As for the build quality of the Koss SB-45, it is generally excellent.  The only negatives here are the quite thin, and looong cabling, and the material used for the ear cups.  The material is comfortable, but it's that very paper-thin fake leather stuff often found on cheaper headsets.  I know from experience with my $20 Sony headphones, it will flake off within two years, and begin sticking to the sides of your face.  I do not know if replacement ear pads are available from Koss, but Radiosport headphone earpad socks work.

I have added an over-the-air recording of the Koss SB-45's, taken from my friend, HL1ZII's cell phone.  It will give you a good idea of how these headphones sound on-air.  As mentioned in the Pros/Cons, the microphone is very clear, but a bit lacking in bass -- what you hear is NOT with +5 Bass (it was +2).  I have since had to make some EQ adjustments to get it closer to where I prefer it (+5 Bass, and 0 Treble).  I would say this headset lends itself well toward contesting and DX work, if you prefer audio that cuts well, or local chat, if you add the Bass.

Enjoy, and give the Koss SB-45 a good look.

Below is the audio, and please FF to :49 seconds to hear what true live sound with the Koss SB-45's is like (the first 30 seconds are recorded CQ'ing).  I must mention, if you hear me cut out during the contact, and say, "I had a short," the problem was actually that I mistakenly pulled-out my PTT switch attachment -- operator error, not the headset's fault!:

Saturday, September 2, 2017

IRIVER Blank IGH-L20 Headset for Ham

First off, I'm pretty sure you cannot buy this directly in the USA, although I am sure you can ship it in from Korea, using G-market (an E-bay-owned Korean company):

The headset is the IRIVER Blank IGH-L20.

Click to enlarge

I have to admit, I've tried many headsets in the budget range.  I almost dropped over $300 to import a Heil Pro 7 here (very glad I did not, given price).  I did end up with the Koss SB45 instead, and that is generally my most used headset, but this one is better on some signals (I switch between the two headsets).

I ended up heading to Yongsan Sun-in building, where dozens of different computer gaming headsets can be tested.  I used a Youtube recording of myself, recorded over-the-air as DX from Korea to Australia by a friend, and played that through various headsets to determine if they sounded good or not.

It was suggested to me that "cheap headsets work best" by another poster here on QRZ.  One might scoff at this, but I have to say -- it's true.  Why is this?  It's because they often aren't as full-range as better headphones.  In fact, the cheap ones often cut the highs, which is a bonus, if you are using them for ham.  Also, most of the electret mics seem to have one of three sounds... they are either a bit high-pitched and lacking bass, average all-around, or a bit bass-heavy.

The good thing is, I can EQ my Icom 7300's TX audio quite a bit, and have found that as long as the electret mic produces a full-enough range of sound (not just tinny audio), I can make it to sound very good.  In general, I find electret mics aren't really muddy, either, so they work very well.

After trying several headsets, I found the IRIVER Blank IGH-L20.  At first, I couldn't get the thing to work!  Then, I found a tiny volume knob hidden on the side of one of the earcups... duh.  After I got the volume turned up, not only did it sound the best on RX, I found the IRIVER is actually built VERY solid, and is comfortable.  It does  a good job of reducing room noise -- fully enclosed, but not everything in the room is kept out.  On RX, the highs are cut at just the right point to greatly reduce HISS noise, yet not degrade the important audio from stations near or far. They are far more comfortable on my ears, for longterm Ham listening.  I was happy to find that the ear cup material is actually decent, and should last a long time.

On transmit, what I found in the IRIVER Blank IGH-L20 is a microphone that leans quite a bit more toward bass, but can it can be EQ'd to sound good, with settings of -4 bass and +4 treble on my ICOM 7300.  Please note that the headset comes without a pop filter, so I added one from an older headset that I threw out, in these photos.  I later removed it, and found it was not necessary, so long as I positioned the mic properly.  In terms of the mic, you also need to watch where the little hole is, which leads to the electret inside.  I find this can adjust itself, and point the wrong way, over time.  That will muddy the audio.  Also note that to use this headset with an ICOM 7300, you will need to purchase the correct HEIL or Ebay seller dongle attachment.

The cable of the IRIVER, as you can see, is quite thick.  The overall build quality of the headset is surprisingly high, given it's $15 price. It comes standard with a dual analog/USB plug attachment.

The fit is a little on the snug side, but not too terribly snug.  It's also made for a slightly rounder head than my USA watermelon-shaped head, so that the top doesn't quite rest on top of my head perfectly, but it is close enough.  My ears fill the inside of the headphones, touching inside, but not uncomfortably so.  The IRIVER headphones also cover my ears more completely than the Koss SB45's, and cut out a small amount more background noise.  They are comfortable to wear with glasses.  It is also worthy to note that these headphones include a tiny, and rather pointless, volume control that was set to 0 from the factory.  It's located on one side of the headset, so check for that if your volume level is low.

I am quite amazed at how much better these sound to me, than the highly-touted Koss SB45's (internally the same as the Yamaha cm500)-- both on RX and mic TX, once EQ'ed.  The IRIVER is also of a higher build quality.

Excellent ham sound, and quality for the Korea price of 17,000 won, or $15 US.

Highly recommended!

Spiderfan 15m, 17m, 20m, 40m antenna, for 1/3 the price

I have been experimenting a lot with portable antennas.  This is an excellent. and EASY multi-band antenna for portable operation, or at your home QTH, provided you don't have very high noise.  You can build it for 1/3 the price of a buddy design, or just the cost of wire, if you have a tall tree.

This resonant 15m, 20m, 40m antenna, which also tunes to 6m, 10m, and 17m, will work DX on the high bands. It is best for short to medium distance on 40m (think most of USA), but will work out farther, if you are up high.

Perched halfway up a small mountain (240m above sea level), I contacted over 20 stations from my HL1ZIX QTH to the EU and the Middle East, in just a few hours.  I was running 90 watts, or less. Most DX stations were 3,000 to 5,000 miles away.  I also worked several contacts between 400 and 2,000 miles on 40m, as well as one contact out to 4,100 miles, in Oman.  Not bad!

Click to expand size
This antenna overcomes a typical problem.  If you have built a dipole, you have learned that it's easy to build an antenna that will work for 15 and 40m, but then you don't end up with a useable solution for 20m without having to resort to adding links (linked dipole), or coils.  Building coils can be a bit daunting for a new ham, and can be lossy.  Linked dipoles are great, but they require you to lower and attach or detach the links when you want to work the other band.

The "Buddy-based" antennas are of excellent build quality, but darned expensive, and they require set-up and change work between bands.  This antenna, which I called "Spiderfan" is both simple, easy to make, and extremely effective.  You don't have to get out of the chair to work all of the bands, once set up.  It does not compromise on any band, except about 1/2 s-unit on 17m, with DX still doable.  On 15m, 20m, and 40m, it is completely resonant and highly efficient!

This antenna is simple to build, because you just need to cut the wires to provided lengths.  The 20m portion should be spot-on.  It's also adjustable by folding ends of wires, but it should be close.  I love this antenna, because I don't need a tuner on 15m, 20m, or 40m, and I can also work 17m with a tuner.  If I want to change bands, I just flip a switch.  No lowering the antenna to tap coils to change bands!  The really nice addition is that 20m is vertically-polarized, so I can work more DX there.  You can also experiment with the 40m legs, adding a lot more wire, and unrolling it for 80m, if you care to work NVIS from that band.

To build this antenna, you will need:

1.  About 32 meters (105 feet) of wire 14awg or 16awg recommended.
2.  An inexpensive 1:1 balun at the feedpoint (not necessary, but highly recommended)
3.  A 12m (40ft) Spiderbeam HD fiberglass pole, or a tree at least that high
4.  Some thin rope for tying the ends of the 40m legs
5.  Some electrical tape, for taping wire to the pole

Here is a video of a contact from Korea to Australia (over 5,000 miles) on a different outing, using this same antenna: