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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
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12th Apr 2011, 9:33 pm | #1 |
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Yaesu FT200
hello there could anyone please help i have a ft 200 and its not receaving in ssb or cw have cheeked the HT rails there fine as well as all the valves are all working fine to did post on another site about this and was told that the FT 200 i have seems to be a one off as its not like the others made for a start there is no VFO extremal plug on the back i will post a few pics of this radio so you can see. please could anyone give me some idea of what could be wrong . i have put a signal into it on AM and it picks up fine
pete |
12th Apr 2011, 9:48 pm | #2 |
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Re: yaesu FT200
Hi Pete
Welcome to the forum. Without a circuit its very hard to tell, it could be a power supply failure or a component that's at fault. I don't have any experience of this particular radio so don't know if its a stock fault, hopefully someone will be along shortly who has. Peter |
12th Apr 2011, 9:57 pm | #3 |
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Re: yaesu FT200
for any one here how needs it i will try to down load the diagram for this radio
hope this will help anyone out there trying to help me sort this poor deaf set out i did forget to say in last post this radio will transmit in ssb and am modes pete |
12th Apr 2011, 10:22 pm | #4 |
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Re: yaesu FT200
Ok, so it isnt working.
We need more information, lets start with some info about you - how conversant with electronics are you? - I know you are a fairly experienced 2E0, just from the age of your call, but have you had any experience in repairing valve based transmitters/receviers? There are some areas of this set that will certainly give you a nasty shock, and possibly worse. Is there any sound at all from the loud speaker? a gentle hum, some hiss, crackling when you change modes/bands? When checking voltages, the voltages on the cathodes of the valves often say more than the voltage on the anodes, or screens. Cheers Sean M1ECY
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12th Apr 2011, 10:37 pm | #5 |
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Re: yaesu FT200
hi sean
i do know a little about the valves and yes i do understand that i can get a nasty belt or worse off them . i do have exprerience with electronics and im also getting help from another ham with more experience with valve sets and electronics you do get a crackle and hum off the speaker in ssb mode in am mode you get voice as well as any white noise have gone as far as using an other psu from a different ft200 to see if that was the trouble but it made no change even down to swapping valves from a working set pete |
12th Apr 2011, 11:07 pm | #6 |
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Re: yaesu FT200
Ok, probably fair to assume two things at the moment.
1, the power supply is ok 2, the valves are ok Why? well, there is some noise coming from the speaker, so this proves that the HT is about right, and the valves that make up the audio, detector, and IF stages are doing something. A decent circuit diagram will be an asset here. Faultfinding on AM will be simplest to start with - SSB makes life a little more difficult, so lets get the easy bit done first. Do you have a signal generator that is capable of squirting any signals in at IF frequency, and at RF frequency - probably 455-470Khz for the IF, and RF - probably ok up to 7 mhz - that way we can prove certain parts of the circuit. Cheers Sean
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12th Apr 2011, 11:14 pm | #7 |
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Re: yaesu FT200
yes i do have a signal generator that will work on 7mhz so will be giving that a try to see what i get out of it will have to do that on Thursday as im not home till then and will post what i find then
pete |
12th Apr 2011, 11:18 pm | #8 |
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Re: yaesu FT200
Ok, looked through the book you uploaded - the IF is 9Mhz - I was hoping for a double conversion with a second IF at 465 KHZ....
Not to worry, first thing that sort of jumps out at me is the 6U8 mixer valve (known as an ECF82 over here) I have had experience of these not performing well when they are a little tired..... First trick will be to squirt a modulated 9Mhz signal in after the xtal filter - see if you can get that to appear out of the speaker, if you can, and it seems good and loud, then try the mixer side of the filter - these filters have been know for their refusal to work.... Report back when you know a little more about what is happening Sean
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13th Apr 2011, 10:18 am | #9 |
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Re: yaesu FT200
Since you seem to be saying it works OK in AM mode then it would seem to point to the carrier oscillator not working, so I would check that out.
It could just be switch contacts connected with it of course, but if both LSB and USB don't work then it points to that valve as the most likely fault location I would say, as it appears to generate both the upper and lower carriers separately. |
13th Apr 2011, 2:02 pm | #10 |
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Re: yaesu FT200
I think he said that SSB transmit is OK (or was he just saying that it ought to be able to do both SSB and AM Tx? - meaning lost in translation), so the carrier osc must be OK - maybe a switch fault on receive?
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13th Apr 2011, 2:16 pm | #11 |
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Re: yaesu FT200
Ah, I missed that. Yes, the carrier(s) must be OK but there is plenty of switch contacts to go wrong.
Check the HT on the carrier oscillators as I see it switches the HT about for this - switches just love that. Last edited by GMB; 13th Apr 2011 at 2:21 pm. |
13th Apr 2011, 5:56 pm | #12 |
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Re: yaesu FT200
I wouldnt be so sure of that - it could just be signals being received at 9Mhz - we are a little thin on the full information to make sure we are chasing the correct areas.
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15th Apr 2011, 3:16 am | #13 |
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Re: yaesu FT200
just to let you all know yes the set will transmit in ssb and am but not receive in ssb
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