The Elecraft T1 Automatic Tuner.

[gil]

Hello,

I have built a couple Elecraft kits, K1 and K2, bought the KX3 and KX2. They make good products, albeit a bit pricey. The T1 is no different, though I do have a couple issues with it aside from the price. Internal K1 and K2 tuners will tune the proverbial wet noodle. I remember plugging in my K1, tuning, only to discover there was nothing at the end of the 25ft coax cable. I had forgotten to plug in the antenna, no problem. Elecraft circuit boards are first-rate. Solder flows around component leads resulting in very nice joints. They also have the best manuals. Everything is packed carefully, labeled and I have never had anything missing from an Elecraft kit.



I have the excellent ZM-2 manual tuner, so why buy the T1 at more than twice the price? The main reason is power handling. Though rated at 20W SSB/CW and 10W continuous, it can take more... I needed a tuner capable of handling 30W for my PRC-320. If I remember well it has been tested at 40W and more for brief moments. The ZM-2 is rated at 15W. Let's face it, who doesn't like to just press a button? Tuning with the ZM-2 can be sharp and it's easy to bump the buttons by accident.

What's not so great about the T1? The case is a cheap crappy plastic box. You'd think for the price you would get a metal case, which is better for any RF circuit anyway. Unlike the ZM-2, it doesn't have a bridge, so you must be careful to use a lower power to spare your finals until the microcontroller finds a match.

You can buy the T1 already assembled but I chose the kit. I was hoping to avoid the VAT and importation tax, but no, the thieves stole €43 from me! I only saved about $20 by buying the kit. Assembly is fairly easy but for a few solder joints very close to others, in particular between the relays where some surface-mount resistors are pre-mounted. You would be wise to solder those relay pins from the other side of the pins, away from the SMT resistors. Other than that, no problem.

I could have bought the internal ATU for my KX2, which I plan on doing later, but then I could not have used it with other radios. Having an external tuner allows putting the tuner at the antenna, thus reducing cable losses. The T1 should tune using as low as 500mW, so practically any QRP rig will do.

I will be putting the T1 through its paces with different antennas. Expect videos... I need to finish it before tonight and the VMARS net on 3615 USB using my RT-320. It's all toroids henceforth, but I like winding them 8)

More will be posted on this thread later.

Gil.

[cockpitbob]

That tuner has been on my list for a while :).  /jealous

I hadn't thought about protecting the finals while it finds, or fails to find a tune.  I can't turn down the power on my MTR and I run it at 12V so it's in the danger zone for a bad mismatch.  Would you worry about using this tuner with your MTR and for example a random wire with 9:1 unun?

[gil]

Hello Bob,

I can't turn down the power on my MTR and I run it at 12V so it's in the danger zone for a bad mismatch.

For my MTR I will use a 9V battery for tuning. I'll just get a 9V battery clip and a DC plug. The T1 is pretty fast, but you do see high SWR briefly while tuning. I don't remember if the MTR reduces power as well in tune mode... For my KX2 I set tune power on 2W, 3W on the RT-320. The MTR is indeed the only one I will worry about, though I have transmitted accidentally without an antenna with it and it was fine. I think it might be more susceptible to a low resistive load.

I finished the T1 last night and it works fine. It tuned my Windom on 30m where I could not transmit before. I definitely want to try it with the EARCHI 9:1 UNUN and the Hybrid Micro from Chameleon.



Gil.

[gil]

[Lamewolf]

That tuner has been on my list for a while :).  /jealous

I hadn't thought about protecting the finals while it finds, or fails to find a tune.  I can't turn down the power on my MTR and I run it at 12V so it's in the danger zone for a bad mismatch.  Would you worry about using this tuner with your MTR and for example a random wire with 9:1 unun?

You guys could build a simple resistive bridge that can be switched in and out of line for tuning purposes just like the one built into Gil's ZM-2 tuner.  A few resistors and a DPDT mini toggle switch, and inline (tune position) the radio has a decent load, when done tuning, just switch it out of line to operate.  If the radio has enough room, the bridge can actually be built inside it !

[gil]

For the MTR a couple 2W 100-Ohm resistors in parallel would work. I choose to power it up with 9V instead of 12. The MTR will work down to 6V.

Gil.