Diagnostic connection means for vehicle mounted radio

In a radio adapted for mounting in a motor vehicle dash, the radio having a case enclosing electronic circuitry including antenna trimmer means having a terminal adapted for connection to an antenna and further having a trimmer adjustment screw, the case having a front plate of electromagnetic shielding material with an opening adapted for access to the trimmer adjustment screw by an adjusting tool from the front of the radio, the improvement comprising, in combination:

• an electrically non-conducting tube extending from the trimmer adjustment screw through the front plate opening, said tube having an inner surface providing access to the trimmer adjustment screw;
• a plurality of electrical contacts within the tube outside the case in front of the front plate, the contacts being circumferentially spaced around and recessed from the tube inner surface and including terminal means projecting outside the tube;
• means for connecting the contact terminal means to selected points of the electronic circuitry;
• at least one additional electrical contact within the tube inside the case behind the front plate, the contact being recessed from the tube inner surface and including terminal means projecting outside the tube and further means electrically connecting said terminal means to the antenna connection terminal, whereby the contact and terminal associated with the antenna connection terminal are electromagnetically separated from the contacts and terminals associated with other parts of the electronic circuitry by the front plate, and whereby the tube is adapted to receive, without removing the radio from the vehicle dash, an adjusting tool for engaging the trimmer adjustment screw without touching the recessed contacts and, alternatively, a test probe with a contact adapted to engage each of the contacts in the tube alternatively by rotation and axial translation through the tube.