Kenwood manual Failsafe device some TS-480HX versions only, 100W final section

Failsafe device (some TS-480HX versions only)

The use of two power supplies and two final amps in parallel is something that has not been tried before, and naturally there may be some anxiety on the part of the user regarding what would happen if just one of the power supplies suddenly failed. Such a situation would be handled safely, since the TS-480 series is equipped with several failsafe devices.

Should a difference of 1V or more be detected between the two power supplies: “RX ONLY” appears in the display and transmission operations are inhibited.

Should the voltage of one power supply drop to zero: if the failed supply is DC1 (Fig. 3), the transceiver is powered down; if DC2 fails, “RX ONLY” appears in the display and only RX operations are possible.

Should a final amp malfunction: if, for example, the output of one of the final amps fell, resulting in an imbalance, “PA-ERROR” appears in the display and transmission operations are terminated.

In addition, there is the usual complement of failsafe devices, including output control triggered by high temperature, high voltage detection, and SWR output control. These failsafe devices will provide temporary protection for the internal circuitry; however, should such a situation arise you should not continue using the transceiver, but rather deal with the problem in accordance with the troubleshooting guidelines.

100W final section

Like the 200W final section, the 100W final section uses 2SC2782 transistors. The drive and peripheral circuits are virtually identical to those in the 200W model, enabling 100W output for the HF~50MHz bands.

For the Japanese market, there are 50W and 10W (50MHz: 20W) models, allowing buyers to choose whichever best suits them – that is, their license and their intended use (mobile or fixed).

It should be pointed out that it is possible to increase the output of these models: the 50W model to 100W, and the 10W model to 50W or 100W. A TS-480 owner who acquires a more advanced license and wants to make use of this capability should go to the nearest service center. Note that it is not possible to upgrade to 200W output.

Also, 50W mobile transceiver warranty certification is available for both 200W and 100W models used as fixed stations.

Ever since the TS-570, Kenwood has adopted a method of converting transceivers to higher output specifications that does not require a kit. Conversion cannot be performed by the individual user, but because this method does not depend on finding stock of the appropriate kit it is proving popular.

Antenna tuner (TS-480SAT)

The 100W model is equipped with the relay-driven antenna tuner that was developed for the TS-570. Since there is no variable capacitor, gears or other rotating parts, this antenna tuner is very responsive and trouble-free. Thanks also to the several preset memories supplied for each band, you can instantly call up settings when moving up or down a band.

You can see the 200W and 100W final sections in Figs. 4 and 5, respectively.

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