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Re: Yaesu FC20
开云体育Hi Andrew, I live in Stanford Le Hope, Essex and my nearest branch was Bow, Maverton way but that has long shut. I think my nearest is in South London but I always order online these days.? De Spence M0STO? Sent while portable! please excuse typos. On 23 Feb 2022, at 20:50, Andrew Lenton <a@...> wrote:
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Re: Yaesu FC20
开云体育I have a business account with RS where do you live ? 73 ? Andrew ? From: [email protected] [mailto:[email protected]] On Behalf Of Spence M0STO via groups.io
Sent: 23 February 2022 16:22 To: [email protected] Subject: Re: [YaesuFT847] Yaesu FC20 ? Hi Andrew, I’ve got a good stock of BAT46 and BAT85’s (used in the FT847) so thank you for the offer. ? ? Fortunately I have a few decent SWR meters and 50w and 100w elements and also aware of the shortcomings of the thruline so thanks for the heads up. I have two bird meters so easy to put a 50H element in reverse and 100H in forward. ? ? The good news is the tuner still works as expected. It still tunes on all bands! As strange as it sounds the processor isn’t affected as far as I can tell but it is in direct connection to the null adjustment circuit however some protection exists. ? ? I’ve put in a small order with Yaesu as mentioned so just waiting for that confirmation.? ? ? ? Many thanks and please keep the thread going guys as the information so far is absolutely dynamite. It’s really appreciated. ? The very kindest regards, ? De Spence M0STO? Sent while portable! please excuse typos.
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Re: Yaesu FC20
开云体育Hi Nina, I have two FT847’s, two FC20’s and two MD100 microphones. Sad I know but also two G5500’s. I went though a phase of buying everything twice when the opportunity came up so can take some close up snaps of my known good FC20.Really appreciated my good friend. Thanks but will take my other one apart when I receive my components. Kind regards, De Spence M0STO? Sent while portable! please excuse typos. On 23 Feb 2022, at 16:12, Nils Ostman <n.e.ostman@...> wrote:
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Re: Yaesu FC20
开云体育Hi Andrew, I’ve got a good stock of BAT46 and BAT85’s (used in the FT847) so thank you for the offer.? Fortunately I have a few decent SWR meters and 50w and 100w elements and also aware of the shortcomings of the thruline so thanks for the heads up. I have two bird meters so easy to put a 50H element in reverse and 100H in forward. ? The good news is the tuner still works as expected. It still tunes on all bands! As strange as it sounds the processor isn’t affected as far as I can tell but it is in direct connection to the null adjustment circuit however some protection exists. ? I’ve put in a small order with Yaesu as mentioned so just waiting for that confirmation.? Will keep you updated. Also noticed the gas discharge tube on the tuning board looks a little smokey. Not put a meter on it yet and doubt it’s taken a hit but they are available from RS Components for about ?6 and I’m a business customer so no postage fortunately otherwise this would start becoming a small but very expensive repair when compared to the cost of a second user ?tuner.? ? Many thanks and please keep the thread going guys as the information so far is absolutely dynamite. It’s really appreciated. The very kindest regards, De Spence M0STO? Sent while portable! please excuse typos. On 23 Feb 2022, at 15:54, Andrew Lenton <a@...> wrote:
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Re: Yaesu FC20
Hi if you used a Bird through line, make sure the element power is low i.e. 50 Watts when using on reflected, as most SWR meters have a more sensitive scale on reflected! The Bird is the same scale in reverse, unless you change to a lower powered element, if you se what I am getting at, That is a bad burn up I suspect it was more than 100 Watts into an open circuit, lets hope the process or is still with us and the board is not too damaged. Bird is ideal for return loss, but not for a low SWR.
Change the Diodes to BAT46, I have some here I can make a matched pair for you 73 Andrew G8UUG in Hampshire |
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Re: Yaesu FC20
开云体育Hi Andrew, the information is spot on and I really appreciate it.? Just waiting for a callback or email from Yaesu UK. They’re pretty good chaps there so normally turn things around quickly. ? As soon as I’m in receipt of my bits I shall go through your alignment tips. I’ve got a really accurate Bird Termaline and a few very good SWR meters too and can use two Bird 43’s one in FWD and one in REV. ? Many thanks and will report back when all is done. Just wish I had a foil layout but can reverse engineer the tracks. ? Kind regards Spence de M0STO? Sent while portable! please excuse typos. On 23 Feb 2022, at 15:23, Andrew Lenton <a@...> wrote:
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Re: A snap of the user manual
Hi This is a standard circuit, once you have replace all the burnt track and
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components, now set the power to 10 Watts, and transmit via an SWR meter into TH FC-20 then into a dummy load on 14.125 MHz, it should auto tune, as it is an easy to match to a dummy load. Check the SWR meter is zero this shows it is tuned correctly, then adjust the Cap TC1001 for minimum on TP1020, TP1008 is the forward power, and is also used by the tuning circuits. Increase the power to 20 Watts check the SWR is still very low, recheck TP1008 and check the voltage has gone up by 6dB. (Voltage 20log (V20Watts/V10Watts). Finally try 100 Watts and you may need to tweak TC1001 for a null. 73 Andrew G8UUG -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Spence M0STO via groups.io Sent: 23 February 2022 13:52 To: [email protected] Subject: [YaesuFT847] A snap of the user manual Following on from my email and see that VF and VR go to the MCU De Spence M0STO Sent while portable! please excuse typos. This email has been scanned by BullGuard antivirus protection. For more info visit www.bullguard.com |
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Yaesu FC20
Hi, a strange question. I had been given an FC20 many years ago by a ham now sadly SK and it seems to have had a mini melt down. Inside near the control port there’s a sensing inductor and the surrounding parts have burned out. As it’s on the input I can only assume it’s been driven with excessive power somehow or some other issue. There is a 20pf trimmer and on the schematic it claims to be Null adjust. I believe it’s in the VSWR forward and VSWR reverse sampling however it’s on the transceiver side so I’m trying to get my head around why the parts burned out. It seems a resistor 27ohm took the brunt but melted TC1001 in the process and much of the PCB tracks. I’m replacing all surrounding components regardless as they amount to pennies but can anyone clarify what null adjust as I can only assume it’s a reference to 50ohm and FSD on reverse.? As it’s coupled to TP1008 a test point I assume one hooks up equipment here to adjust null.
If anyone has a service manual about as I’m not sure one was ever issued. Any information on what null adjust is would be helpful if it’s in the service manual. Many thanks in advanced, De Spence M0STO Sent while portable! please excuse typos. |
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Re: CAT - Control - Yet another post
Ian
I've been running JTDX with JTAlert and OMlog for so long that I can't recall whether Omnirig is used at all here, certainly not loaded as a seperate item. Attached is a screen capture of my JTDX Radio config page. All I get out of it is PTT and the reporting back of frequency, the 847 has really limited CAT functions, no S meter or such. 73 de Ian VK6CR |
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No TX on AM, SSB, on All Bands FM works fine
I wonder if any one can help me, my FT847 stopped transmitting on LSB, USB and AM, FM is fine with Full 100 Watts on HF and 50 Watts on VHF. I traced the audio going in and it gets to Q1043 at TP 1035, there in no audio I removed Q 1063, and the audio is back, Q1063 is is a voltage controlled attenuator, as it has an OP Amp on its input, this could result in a "virtual earth" on pin2 and the signal is getting dropped across the preamp transistor, however there is nothing coming out of Pin 4 which goes off to the Balanced Modulator eventually. There is a good 455 KHz if signal present at the Balanced modulator.
? ?The mic audio enters the radio via Transistor Q1043, then trough a cap into Q1063, on TP 1035 three was no audio! Rather odd. No Q1063 is an electronic controlled attenuator controlled by a voltage on pin 3, this voltage come from IC1093 pin 3. Now IC1093 is a strange device it received digital data from Q1105 the main Yaesu 100 pin microcontroller, as you turn the mic gain control up and down it sends a series of data to Q1053, and this turn send a voltage out to control the attenuator. To make matters more interesting the data is only a few bytes sent in less than a milli-second ?and only when you change the mic gain or select AM SSB, CW, of FM, the data is not continuous. My 2GB/S digital scope did capture the data, without it I would have been snuck! ? I do not have a decent copy of the FT847 service manual, all the ones on line are photocopied and low resolution and when you blow them up they are unreadable, however, Roger came to my rescue, as he had a genuine FT874 service supplement. ? Anyway this took 5 days to sus out, as I had no block diagram and no component over lay that I could read, so it took me up to 4 hours to trace each part and make measurement, some components were on the reverse side of the AF main board. To make matter worse, there are some undocumented mods on the back of the board close to the audio input attenuator, This digital transistor shorts out Pin 3 and 5 on IC1063, which increases the attenuator to Max, i.e. no AF signal leave pin 4 to the balanced modulator for SSB and FM. ? However, there should be a healthy signal on Pin 4 and there is none, as the voltage goes up and down on Pin 3 in sympathy with the Mic gain control, the inhibit is not active. ( I have no idea when the inhibit kicks in) I have enclosed the data sheet for IC 1093, by no means a simple device. ? Removing IC 1063 restores the audio to TP1035, :? ? I have ordered a new attenuator chip, and will solder it when it arrives fingers crossed! ( I am not holding my breath on this one) ? 73 ? Andrew ? ? ? ? ? ? ? ? ? |
Spence G5STO
Andrew Lenton
Nils Ostman
