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Hardware Help
G1MFG 23cms TX
SUGGESTED MODIFICATIONS
BY
Martin G8KOE TO USE TX ON GB3VR
| Unmodified G1MFG 23cms TX |
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| Follow track to the right of yellow preset, remove chip capacitor and also the 470mfd on main PCB. Fit a link in place of 470mfd if Pre-emphasis is to be fitted externally. |
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| Fit 47mfd -ve to video input pin +ve via gray wire to right pad of removed chip capacitor. This bypasses internal video processing and level preset. |
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| Fit a Pre-emphasis network. This can be fitted to the PCB by rearranging the preset etc as shown or fitted externally. |
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| Also fit a 75ohm resistor after the Pre-emphasis network and a 100pF capacitor across the video gain preset on PCB from hot end to wiper. This will improve the HF response. |
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| MOD's from Martin G8KOE |
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| After the above MOD's good pictures can be seen via GB3VR. ( The TX suffers from a lack of low frequency response and can suffer from poor frame lock on some monitors. ) |
