Home > Daily News, HF, Home Brew > Linear Amplifier and IC703

Linear Amplifier and IC703

I arrived home after 3 days in Cairns to find the Tokyo Hy-Power HL-200E linear had arrived in the post. I bought this amp from a private seller for a very reasonable price. When I attempted to drive it with the IC703, I had no success at all. I spent some time investigating why it would not work. The amplifier was set up to utilise RF sensing to switch PTT, but this would not work with the 703 for some reason. I eventually modified the switching to pull the relay utilising the 703’s 13 pin plug which got the amp working just fine. I don’t yet have a power meter, but a few quick calculations of amps drawn and volts supplied put me in the ballpark for power while staying safely below my license limits. Update- I used the amp quite successfully to talk to a number of stations including VE7POH on 40 metres SSB, but when I went to use it this morning on 80 metres, I had some problems with the 703’s ALC going crazy and overdriving the amplifier. The 703 interfaces with my iMacG5 via MacLogger DX software, which I had running, along with Cocoamodem which I use for PSK. When I stopped Maclogger DX, the problem went away, so I obviously have to do some more troubleshooting. In the interim, I will not run Maclogger while utilising the amplifier.

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Categories: Daily News, HF, Home Brew
  1. Dave Catlin
    February 22, 2014 at 6:42 am

    I also have a THP-200E. Bought it at WYONG many years ago. Did not come with a manual but could get 100Watt plus out of it when driven by my FT-817. Good amp must be well grounded otherwise nasty RF burns can be an experience. I am assuming it can deliver 200W SSB? Cheers Dave VK2JDC

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