is provided for connection to an optional ac adaptor). In order for the manufacturer to get Type Approval of this game, he will most likely have to add extensive additional filtering to this dc power interface. This is clearly a case where the buyer is being penalized on the basis of a potential interference-causing condition which will never exist (unless, of course, he has a 6.3 Vdc outlet in the wall of his living room.) Again, this is a situation which will not change without a concerted effort by the Industry.
Now consider the third test in our list above. The procedures used by the FCC to measure the spectral (i. e., function of frequency) levels of electromagnetic energy which are applied to the terminals of the TV set are delineated in Paragraph 2.0 of FCC BULLETIN OCD 33, Dated May 1973, and entitled FCC TEST PROCEDURES FOR CLASS I TV DEVICES SUBMITTED FOR TYPE APPROVAL UNDER PART 15. Although the FCC apparently does not attempt to configure the various wires and cables, which form a part of the fame being tested, to obtain a worst case configuration, experiments by the writer have confirmed that such configurations do indeed have a significant effect on the outcome. For us this is bad news, because here again the Rules do not precisely specify how the game is to be configured during the Type Approval test. This situation needs to be improved.
But there is yet another serious problem with this test. Because the spectral energy levels are being measured on the game's balanced 300-ohm output terminals, some sort of matching network is required to interface with the unbalanced 50-ohm-output of tuned RF voltometers and spectrum analyzers. To achieve this 300-to-50 ohm match, the FCC is currently using a device (balun) which, according to its manufacturer, is not presently in production. (The writer's considerable efforts to obtain one of the devices, on a cost-is-no-object basis, were unsuccessful.) However, even if the device were readily available, its use for this particular type of measurement is questionable for a number of technical reasons. There are alternate ways for performing this test using readily available components, and experiments by the writer have demonstrated both feasibility and the simultaneous reduction in test setup variables. But in order to carry any weight, such experiments need to be formalized, verified by several competent authorities, and the results used as rationale for a concerted petition from the Industry to the FCC.
The measurement of Transfer Switch isolation is performed by the FCC using the same techniques as those used to measure the 300-ohm spectral energy levels. The FCC is very concerned about the level of switch isolation, and rightly so. The switch is the only thing which prevents the RV energy generated by the game from being transmitted in a relatively efficient manner from the TV set's antenna. However, we are again faced with a situation in which variations in the test setup play a significant role in the ability of the game to gain Type Approval. (Currently, of all the Subpart H tests, the FCC seems to examine the Transfer Switch isolation with the greater vigor.) Once again, it behooves the Industry to get together, and in a unified manner develop a technically justifiable test method which will permit us to accurately predict the ability of our designs to gain Type Approval before they are submitted.
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