The personal website of Scott W Harden
Source code for Improved MEPT Enclosure
---
title: Improved MEPT Enclosure
date: 2010-11-14 20:22:38
tags:
  - qrss
  - amateur radio
  - circuit
---

# Improved MEPT Enclosure

__I've been pretty busy lately__, but I drip to the hardware store with the XYL produced a PVC enclosure that looked perfect for my ongoing MEPT (manned experimental propagation transmitter) projects. I didn't want to buy it (it was a little pricey by my standards, at $6 USD, which is about the total cost of the transmitter!) but the wife convinced me and I'm glad she did!  I intended it to replace the styrofoam enclosure I had been using, but I wasn't thinking clearly and drilled holes in the box and mounted screws through them.  While electrically this is a wonderful way to add antenna connections, thermally it was a bad idea.  The main point of the enclosure was to be temperature stable! Oh well. I put the whole thing in the Styrofoam and as a test, I'm leaving it outside tonight. I can't wait to see how it goes!  Here are some photos of the project.

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![](IMG_4526.jpg)
![](IMG_4534.jpg)
![](IMG_4547.jpg)
![](IMG_4548.jpg)

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__Update:__ Even when being housed outdoors when temperature fluctuations vary greatly between day and night, this MEPT is surprisingly stable! When I open the box, it's very warm inside, so I am thinking that the voltage regulators and the MOSTFETs of the PA are heating the device nicely.  Here's a capture spanning about 2 hours. The vertical height of each "V" is about 10Hz, so I estimate that for this span of time, drift is <1Hz.  However, I do believe that long term (day to day) frequency stability is still not optimal, but only time will tell.

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![](qrss_stable.jpg)

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__Signal report__: briefly, this is my signal in Alaska courtesy of KL7UK. My signal is the V-shaped one near the bottom: 

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![](KL7UK_alaska.jpg)

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