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10dB attenuator for Johnson and OtherTransmitters. Cuts the Transmit power to 10% of the total output NEW!
This 10 dB attenuator for Johnson and other Transmitters, cuts the Transmit power to 10% of the total output.
NOTE: This is a special order item and it may take about one week to ship rather than the normal same day shipping.
This is a great item if you are driving a modern Amplifier with a vintage Radio like a Johnson Viking Valiant or driving a vintage grid driven Amplifier like the Johnson Thunderbolt.
This listing is for the 10 dB unit which cuts the transmit power to 10 % of the input power to the attenuator. I also have a 6dB unit in another listing which will cut the power to 25% of the input power and works great with the Johnson Viking Ranger or any Transmitter in that power output range.
These units have a bypass switch so when you do not need the attenuation you can bypass the attenuation circuit with the flip of a switch
This is a brand new product and I will extend a satisfaction guarantee or your money back including the shipping cost.
Transmitting Attenuators: These attenuators Can be used with any Vintage Transmitter to reduce the power so you can use your transmitter to drive a modern HF Linear Amplifier.
The also replace those that were being made for use with Johnson transmitters when used with Grid-Driven amplifiers such as the Thunderbolt. Those units were designed for 350 ohm impedance which made them basically useless when used with modern equipment with a 50 ohm fixed output. Also, the attenuators built to the Johnson design had two versions, a �high power� version which was intended for use with transmitters such as the Valiant and Viking II, and a �low power� version which was intended for use with the Ranger. The �high power� version incorporated an incandescent light bulb which further affected the impedance.
These new attenuators have an impedance of 50 ohms which allows them to be used with virtually all equipment in use today (including �boat anchor� equipment). Also, they have a higher power handling ability. The design now employs resistors with a maximum power rating of 150 watts and also has a heat sink attached. However, running much over 100 watts into the attenuator is discouraged.
Another feature of these attenuators is that they are symmetrical, unlike the Johnson design which had a definite input and output. That is, the attenuators can be installed with the input and the output cables going to either jack.
The attenuators are available with the following attenuation:
6 dB (actually 5.8 dB) which reduces the power to about 25% of the input power.
10 dB (actually 9.93 dB) which reduces the power to about 10% of the input power.
A transmitting attenuator can not only be used with Grid-Driven amplifiers, but can be used in other applications where the output power of a transmitter needs to be reduced. Of course, the attenuator also works on received signals.
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