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Can FT-847 power 2 preamps with total current of 400mA
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I just acquired a used FT-847 and plan to use it for VHF/UHF work including getting into satellites. I have one question. I plan to get preamps and am looking at 2M and 75cm mast preamps from Advanced Receiver Research. They require 200mA each. The Yaesu manual says it can supply 300mA to the VHF AND/OR UHF connectors. I am confused if this a total for both connectors conbined or 300 mA each? Looking at the schematic I see there is one current limiter for both connectors so I assume this is a total number. I am wondering if anyone has run into this?
Thanks, Bruce, WB6IZG |
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Douglas Richards
开云体育Morning Bruce I just looked at the website
for Advanced Receiver Research, and they say all their
receivers require 25ma. Well within the parameters for the 847. Even the military receivers were at 25ma. Hope this helps. Happy Hunting Stay Safe 73 Douglas Richards VE3FFR
On 10/20/2020 1:04 AM, Bruce Forsberg
wrote:
I just acquired a used FT-847 and plan to use it for VHF/UHF work including getting into satellites. I have one question. I plan to get preamps and am looking at 2M and 75cm mast preamps from Advanced Receiver Research. They require 200mA each. The Yaesu manual says it can supply 300mA to the VHF AND/OR UHF connectors. I am confused if this a total for both connectors conbined or 300 mA each? Looking at the schematic I see there is one current limiter for both connectors so I assume this is a total number. I am wondering if anyone has run into this? -- 73 Douglas Richards VE3FFR ve3ffr@... |
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The preamps I was looking at were the 160 Watt thru power premaps (MSP144VDG-160 and MSP432VDG-160). These require 200mA each during RX. After further investigation I thought the UHF port was broken since I could not measure 12V coming out. I had menu items 29 and 30 turned on. But after more investigation it turns out 12V only comes out when you are receiving?in that band as well. Therefore?I will not be powering both preamps at the same time. Way to go Yaesu. It looks like I am good. Bruce, WB6IZG On Tue, Oct 20, 2020 at 5:04 AM Douglas Richards <ve3ffr@...> wrote:
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Hello. Sorry, but I don't?understand?why you may be looking for trouble?connecting the DC supply of the AR's LNA's to? the FT-847. I can tell you that after 6 months of working on a faulty FT 847, that it's an? old radio, not enough technical support and a shortage of obsolete?spare parts. Isn't it simpler to use an?external power supply? 73 Mike ?4X1LM ?? ??????? ??? ??, 20 ????? 2020 ?-13:54 ??? ?Bruce Forsberg?? <?bruce.forsberg@...??>:? I just acquired a used FT-847 and plan to use it for VHF/UHF work including getting into satellites. I have one question. I plan to get preamps and am looking at 2M and 75cm mast preamps from Advanced Receiver Research. They require 200mA each. The Yaesu manual says it can supply 300mA to the VHF AND/OR UHF connectors. I am confused if this a total for both connectors conbined or 300 mA each? Looking at the schematic I see there is one current limiter for both connectors so I assume this is a total number. I am wondering if anyone has run into this? |
开云体育But does the 847 not supply the required voltage?? It is not from the pre-amps.? The radio powers the pre-amps. Grim? - ZL3TV On 21-Oct-20 8:27 PM, Michael Luft
wrote:
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HI Bruce
quietly use two preamps through MENU 29 and 30 UHF-AMP and VHF-AMP power supply
The FT847 is not full duplex, so it will only feed one at a time and the current, at least with my LNAs, have had no problems.
There are also two things to know: 1 if you have an instrument or a PA after the radio, you risk that the power does not go through and short out before the instrument for its possible components on the line
2 when you activate the external one, the internal one can no longer be activated.
Personally, I preferred to feed separately after PA and pwr / swr METER, both because after the PA they cut off the power supply and in case of having 2 LNBs in series that can always be used, either one or the other or together, even if then it increases the NF considerably. 73 Franco |
Frank
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