11/25/12

Last Project of the Year-Tube Headphone Amp

41xLzbeWL-L._SL500_AA300_This is just a little write up for you all of what I think will be my last project of the year. This one was an easy one. I did very little work on it. Mostly just a few modifications of a previous design and when everything arrives, assembly. Now as I said, not my original design this time, but that’s ok. It’s a epic design none-the-less.

What is it you ask? A Tube Driven Headphone Amplifier. Link below.
http://diyaudioprojects.com/Solid/12AU7-IRF510-LM317-Headamp/
Specifically it is a 12AU7(ECC82) Tube / IRF510 MOSFET Headphone Amplifier.

It uses one 12AU7 vacuum tube for signal amplification and a pile of other great passive components and a few semi-conductors.

So far I’m not very far into it. I have ordered all my parts. As of Sunday November 25th I have received:

  1. Groove Tubes ST-12AU7 Preamp Tube Silver – Link
  2. 9-Pin Tube Socket Ceramic PC Mount – Link

Printed Circuit Board – PCB

In addition to all that I’ve also out-sourced my PCB construction to a pretty awesome service. Which is called OSH Park. These guys, best I can tell, round up multiple orders for PCB’s and submit them as one board to there builders. This makes it worth while money wise and your not stuck with 50 copies of one board. This is what has forced me in the past to make my own PCB’s. Which I hate to do!

With this service you create your circuit board in Eagle CAD and then upload your design to there website. It will ensure a proper design and tell you how much your going to be charged. It also renders you out pretty pictures of basically how your board will look. I included mine below. Now when you order, you have to order in multiples of 3, but that beats 50 or more. I paid $21 USD for my project. Which to me, that’s not bad. I’ve got 3 boards coming, that’s 7 bucks a piece. I can sell 2 of them if need be to pay for the entire project easily.

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11/21/12

Second Operating Positon

Following my experience from Field Day 2012 I’ve been thinking. What can I do? I did help as much as I could with setup and operating, but I did not really contribute anything. So between now and the ARRL 2013 Field Day I’m trying to get things together. Being I am now a General Class operator with plenty of operating privileges I will be acquiring a HF capable transceiver. I’ve also recently gotten a mobile dual band rig. As written about previously.

What I did today was wire in a second operating position in my SUV. Version one of what I did was to simply run 2 CAT6 cables from the radio mounted area to the back of the SUV and crimped on RJ-45 connectors. I then used f-f couplers to hook everything together. This worked just fine, but had 2 flopping cables in the back. You know, flopping around. Well that was version one.


Version 2 is a little more buttoned up. I’ve maintained the same cables running to the back from the radio. Now, instead of 2 RJ-45 connectors at

 

the end of these two cables, there are two keystone sockets. One to plug microphone and one for the control head. This way the look i cleaner and a little more flexible interface. To house all this I picked up a slim electrical box. I put some 3M Velcro strips to hold it in place. And finally I simply mounted my keystones in a 6 port face plate. See the keystones you buy with various sockets and plugs are a universal square snap in fit.

Why go through the trouble you ask? Well as I mentioned I’m doing this in preparation for Field Day. I imagine myself sitting in a chair working my radios from the car. This is so I can go flip the two cables and plug up to setup a station in the back. That simple. I don’t have to un-mount the radio, find power in the back, plug everything in and then be on the air. 1 minute and I’m going. I would love to find some switching device that would let me jump back and forth without having to go to the radio and switch cables.

What do I have left? Well not much if I’m honest. Directly for this project I need audio in the back. 2 speakers. Specifically the MFJ 281 ClearTone Speaker. What I’m planning on doing is fabbing up a bracket to mount the speaker right inside the SUV to the roof. I’ll setup an audio switch of some kind to send it to the back and I’ll have either 1/8 jack keystones or