- The TEGAM RF LEAK Memo, which outlines the problem, impacts, and solutions for TEGAM products.
- A paper presented by NIST at the 2007 MSC meeting that gives NIST findings on the same issue.
After writing the memo, we noticed that the installation of the filter is not very clear. The TEGAM filter is to be installed as close to the mount bias terminals as possible, preferably by plugging directly into the mount. If a 4-wire connection to an 1806 is desired, we recommend connecting the filter to the mount and both source and sense leads to the filter. Alternately, separate filters at the 1806 could be used for source and sense. The TEGAM 1000027 filter has a series resistance of a few milli-ohms, and therefore will not impact readings at frequencies where leakage was not impacting results before.
The 1000027 filter is designed to keep RF energy out of the Type IV (and Type II) circuits and therefore will have negligible impact if installed in the voltmeter leads.