Posted: 9/21/2010 3:55:26 PM EDT
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ok, I got my ft-2900 today. but, playing with it i found something not working right. basically what happens is when I try to tx on 75w it shuts off.
calculations: 13.8 v at 75 w means I need 5.4 amps, well its hooked up to a 25 amp power supply... the antenna I have plugged in is a 2m slimjim made by N9TAX. connections all seem solid. am I missing something? |
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You need 15 amps to power the radio at 75w. 9 amps at 30w. I would guess your power supply is not up to the task, can you transmit at less power without it turning off?
I was under the assumption that if the supplied voltage drops to low or high the radio will turn off, is the power supply adjustable voltage? |
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Quoted: You need 15 amps to power the radio at 75w. 9 amps at 30w. I would guess your power supply is not up to the task, can you transmit at less power without it turning off? I was under the assumption that if the supplied voltage drops to low or high the radio will turn off, is the power supply adjustable voltage? I can transmit on everything else, just not 75 watts. it is not a variable voltage power supply, but that doesn't mean that the voltage isn't dropping lower than required. should I expect problems with my powersupply I odered? its a SEC-1235M
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From the specs:
15A (75W) / 9A (30W) / 5A (10W) / 4A (5W) 25A should be completely sufficient. Are you using the radio's power cord connected directly to the PS, or do you have any adapters or wires inside that might screw it up? If not, that leaves the radio, antenna cable, or antenna as the source of the problem. Probably one of the latter two. |
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Quoted:
Quoted:
You need 15 amps to power the radio at 75w. 9 amps at 30w. I would guess your power supply is not up to the task, can you transmit at less power without it turning off? I was under the assumption that if the supplied voltage drops to low or high the radio will turn off, is the power supply adjustable voltage? I can transmit on everything else, just not 75 watts. it is not a variable voltage power supply, but that doesn't mean that the voltage isn't dropping lower than required. should I expect problems with my powersupply I odered? its a SEC-1235M I doubt you will experience problems with the power supply, the Samlex brand is highly loved here it seems. This forum advised me to get a SEC-1223 and I have been happy. Do you have an SWR meter? High SWR would cause shut down I believe. However, I am guessing the power supply just cannot supply the juice. |
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radio is plugged straight into the power supply, no SWR meter though I have access to one. my antenna is brand new from N9TAX I'm assuming that someone who makes as many antennas as he does knows how to make a 2m antenna. it could be the antenna cable, its not mine and kind of old... ETA: im going to buy a new antenna cable right now, I need one thats mine anyway, cant live of other hams forever. |
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Quoted:
radio is plugged straight into the power supply, no SWR meter though I have access to one. my antenna is brand new from N9TAX I'm assuming that someone who makes as many antennas as he does knows how to make a 2m antenna. it could be the antenna cable, its not mine and kind of old... ETA: im going to buy a new antenna cable right now, I need one thats mine anyway, cant live of other hams forever. Make sure you get one with the correct impedance. You don't run a 75-ohm antenna on a 50-ohm cable or vice versa and expect success. |
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Quoted: Quoted: radio is plugged straight into the power supply, no SWR meter though I have access to one. my antenna is brand new from N9TAX I'm assuming that someone who makes as many antennas as he does knows how to make a 2m antenna. it could be the antenna cable, its not mine and kind of old... ETA: im going to buy a new antenna cable right now, I need one thats mine anyway, cant live of other hams forever. Make sure you get one with the correct impedance. You don't run a 75-ohm antenna on a 50-ohm cable or vice versa and expect success. it does work now on 75w so im assuming it was the cable, although my apartment doesn't seem to like it when I tx on 75w
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Your apartment doesn't seem to like it? Is it, like, screaming or something?
Are you using the antenna indoors, or at a low elevation just outside? At 75W, with the antenna relatively close to other household electronics, it will be very difficult to avoid interference. For a number of years I ran a 2M FM packet station at 160W and with a very good antenna mounted at one end of the house just above rooftop level. It provided solid coverage within a 30-40 mile radius at the expense of some local RFI. There was still a little bit of herringbone in the old analog boob tube even after working over the interconnecting cables, etc. in the entertainment stuff. That's a lot of power, 160W or 75W either one, and the best way to avoid RFI is to get the most vertical separation you can between the source and the "victim" of the RFI. In my case, the rooftop wasn't quite high enough but we do the best we can. |
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It is unfortunate they don't provide a more reasonable power level to use in that 75W rig. 5W is a bit light but 25 will get you just about anywhere 75 will. But it has been the trend for the last 25 years or so to make VHF/UHF mobile rigs increasingly powerful. Even so, 75W won't increase your signal on the receiving end even a whole S-unit over that of a 25W unit.
They're just selling bragging rights IMO. For bragging rights I'd rather pass my Extra without studying (and did)  .
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Quoted: It is unfortunate they don't provide a more reasonable power level to use in that 75W rig. 5W is a bit light but 25 will get you just about anywhere 75 will. But it has been the trend for the last 25 years or so to make VHF/UHF mobile rigs increasingly powerful. Even so, 75W won't increase your signal on the receiving end even a whole S-unit over that of a 25W unit. They're just selling bragging rights IMO. For bragging rights I'd rather pass my Extra without studying (and did) .for the most part ya, I'm wondering how much more ill get considering I live in the great flat state (North Dakota) the power increase along with a real antenna would probably work out a lot better though.
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Quoted:
ok, I got my ft-2900 today. but, playing with it i found something not working right. basically what happens is when I try to tx on 75w it shuts off. calculations: 13.8 v at 75 w means I need 5.4 amps, well its hooked up to a 25 amp power supply... the antenna I have plugged in is a 2m slimjim made by N9TAX. connections all seem solid. am I missing something? Radios are less than 50% efficient. With your radio, FM, unlike SSB, it is drawing continuous power for a given power output regardless of modulation. According to the manual, you need 15 amps to transmit at 75 watts out. Apparently your power supply is not adequate to the task, voltage drops when you transmit at 75 watts, and that's why it shuts off. Also, don't put that antenna against a wall. Put it out in the middle of the room, or hang it in front of a window. If you do that, make sure there are no metal venician blinds or aluminum window screen. Nearby metal will mess up SWR. A friend with the same N9TAX 2m antenna was getting very high SWR, lots of heating on the radio and the ferrite bead on the feedline with his hung up by the blinds, which he assumed were plastic... not! But hung from the ceiling fan in the room, no heating, good output, and he can hit all 10 of the repeaters in the Pensacola area with ease. Also, the SEC-1235M will power your radio with no problem. The SEC-1223 will easily power it, too. |
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Quoted:
 there we go, all the essentials right next to my bed. my Power Supply came in today, powersupply says 13 amps at 75w When you get your General or Extra ticket, you can use the same power supply for a 100 w HF transceiver. It will be able to run your 2m and HF rigs, plus accessories, as long as you don't try to transmit on both simultaneously, of course. |
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Quoted: Quoted: http://img42.imageshack.us/img42/2554/imag0070eb.jpg there we go, all the essentials right next to my bed. my Power Supply came in today, powersupply says 13 amps at 75w When you get your General or Extra ticket, you can use the same power supply for a 100 w HF transceiver. It will be able to run your 2m and HF rigs, plus accessories, as long as you don't try to transmit on both simultaneously, of course. |
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Oh, that was you... duh.
OK, back to work! Study, study, study! Don't quit now! One guy suggested, and it sounds like a good idea, to print out the question pool. Then take a magic marker, not a highlighter, and cross out all the wrong answers. Study the questions and only look at the correct questions. Don't stay up cramming all night the night before a test. You want to arrive rested and ready. |