AmateurLogic Shorts 4: Unboxing the Icom AH-705 Compact Auto Tuner, one screw at a time.

I had a G90 (and still do) and it made a great portable, but after playing with a friends 705 I picked one up. While I prefer to use a 49:1 EFHW as it is small and resonant, sometimes, on some bands, you do need a tuner. While the cost on the AH-705 is up there, my biggest complaint is that not only is it expensive, it's freaking HUGE as well. I could deal with Expensive but small or large but inexpensive ... but not both. So I went to HRO and for almost $200 less, got the LDG Z-100PLUS/IC-705. Not only is it less expensive, it's smaller, but will also tune a wet noodle. Additionally it can be used on my IC-7300 and G90 as well.

If I really need a tuner and concerned with being light weight, I'd go with a manual one from QRPGuys.

Sorry iCOM, hard pass on the AH-705 for the size and cost.

 

I have the same one and I am very pleased with it. I just don’t understand why they don’t do the same, but in a protected case, even if it will be 50 bucks more expensive.

 

When I had an 817nd, I used a QRPKits SOTA EFHW tuner and a chalkline reel with 70-odd feet of 28awg wire, which gave me 4 bands, was light, and inexpensive. It wasn't always the most convenient solution, but it worked well. I think QRPGuys makes an identical model, but with less polish (lighter and less expensive).

Chris

 

I use the single LED SWR meter from QRP Guys with my MTR and QCX Mini rigs. I connect the meter to the rig and make sure the switch is in the TUNE position before connecting the antenna or keying. Only after I'm satisfied I have a good SWR will the switch get moved to the OPERATE position. When I'm done and ready to change anything related to the antenna, the switch goes back to the TUNE position.

I use a linked EFHW for 20/30/40 which is <1.5 on the CW section of the listed bands. It works magnificently. The SWR meter is my sanity check to prevent your concern about ruining the radio.

$15 and 30g vs $350 and 450g. No question which one I'd use for SOTA. That tuner along weighs in half of what my entire SOTA rig comes in at.

 

Rich, I have to get to the point where I am operating cw for sota. I am packing in 15 pounds just in radio gear! I am so darn jealous of you guys... It's ultimately the only choice for any serious mountaineering. I am going to find you out there one of these days and have you qrs for me. And this is totally on me, the cw resources out there are fantastic! Me not so much! Hope to hear you soon.

Mindy

 

The Icom AH-705 is just a solution looking for a problem IMO. Especially given the size for what is intended to be portable. It takes very little effort to make a resonant end fed. Cheap VNA, cheap reel of wire, a 49:1 Transformer and a pair of wire cutters. Resonant Dipole, or even linked dipole isn't much more work. Each to their own but I just don't understand why people aren't using resonant antennas. Why make life harder than it needs to be?

Are there any advantages to using a non resonant antennas over resonant ones? (genuine question!). Yes, I know a tuner can tune a wire to all bands but how many of us really need or want and 'all band' antenna when operating portable?

 

I've been doing a lot of testing for POTA and SOTA lately and I have proven to myself that the KX2 with the tuner built-in is the smallest package I can find. That being said, I have a KX3. With the bands getting better, I've had no trouble running QRP, I haven't run 100 watts since early last year. I'm using a Buddipole or Sotabeams dipole for POTA (resonant-ish) and the Sotabeams dipole or the Versa-Tenna End-Fed from K7BHB (Ebay), which needs a tuner, but only weighs a few ounces.

 

There are different situations. And not always a non-resonant antenna is ineffective. I think an online translator will help you read this article where the antenna impedances are described http://dl2kq.de/ant/3-57.htm

Therefore, my homemade radio has a built-in tuner and there are always two pieces of wire, 7.5 meters each. It was such a set that allowed me to effectively be on the air in Turkey, where I did not know in advance what kind of antenna I could make.

http://www.us7ign.com/?p=644

 

The only advantage is the ability to use multiple bands without changing antennas. That comes at a price, but convenience wins the day when you're portable. The best work around for me has been a linked dipole from Sotabeams. Its resonant, portable and works great, no tuner needed. You really can build your own, these are not complicated devices.

 

Why on earth would you want to take it apart?

 

No you don't. you just need a separate wire for those bands that you can plug in into the 1:49 un-un box. Banana-plugs do just fine there. Much cheaper than an automatic tuner.

 

You should review it on eHam. I spoke to LDG and they said that no one has yet reviewed the combination of Z100Plus and IC-705 -- I'd love to read it, because the little LDG made specifically for the IC-705 garners really lousy, mixed reviews.

 

You don't need a separate wire for each band. I use a linked EFHW and can run 20/30/40 on one wire by (dis)connecting the proper links. Takes about 60 seconds when I'm doing a SOTA activation. Loosen the feed end to give the wire some slack, make your adjustment, and then tighten everything back up.

In fact, I just has an epiphany where I'm going to add a small clip to the rope that I use to secure the feed end of the EFHW so I don't have to untie an end to get some slack to adjust!

 

Tried working you this past Saturday but no copy.

I QRS'ed down to about 10wpm two two people yesterday. I usually wind up making a mistake (usually a missed dit at the end of a character) since I'm used to running 18-20wpm. But, this lets the (most likely) new person on the other end know that we ALL make mistakes and not to be afraid to try! If you never make a mistake sending CW, then you are a keyboard jockey!

 

Yes, but not really for QRP. For example, if you feed a dipole with true open ladder line (ie spaced 4-6" apart), while the dipole may not be resonant on all bands (and in reality, the best isn't resonant on any band at all), it will allow you to get virtually no loss as compared to coax.

For example, and antenna fed with 100 feed of 6" ladder line, with 100 watts, will only suffer 0.139dB of loss. Compare that to LRM-400 which has 0.865dB of loss. At 50Mhz.

https://www.trueladderline.com/w7fg-design-dipoles/