Re: FT-101ZD MK2 AM BOARD looks odd / modified???
Hi Cuck, very interested in the mod you suggest. All I have seen to overcome the narrow AM audio bandwidth after fitting the 6kHz filter involves fitting a relay to bypass the next, (width filter - 2.7kHz ?), If there is an easier way that's great. Any further info most appreciated. Thank you.
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Re: FT-101ZD MK2 poor sensitivity ..
Soooooo .... after going back and forth and head scratching and wondering why the Marker Signal goes through but RX is very weak I by
coincidence found out that you have to apply the marker signal with a 50 Ohm terminator.
If I test with a terminator the S-Meter does not move when I dial to 14.2MHz.
So, there you have it.
:)
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Re: FT-101ZD MK2 AM BOARD looks odd / modified???
Thank you? ddelectrical,
That's reassuring :)
I also got my AM board to work, it was a mix-up in the coax connectors (there are 2 of them, and they're both grey)
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Re: FT-101ZD MK2 AM BOARD looks odd / modified???
OK, here are the pages?from the FT newsletter?- it requires swapping pins 3 and 4 on IF Board J03.??
On Sat, Jan 22, 2022 at 9:01 PM Bruce Collins < kb0tj1@...> wrote: Post it here if possible.?
I have two MKIII radios and two of these optional AM boards. I’d like to install them correctly myself.?
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Re: FT-101ZD MK2 AM BOARD looks odd / modified???
Post it here if possible.?
I have two MKIII radios and two of these optional AM boards. I’d like to install them correctly myself.?
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Re: FT-101ZD MK2 AM BOARD looks odd / modified???
There are two pins on one of the IF board plugs that have to be swapped. Pin 3 and 4 of one of them will send all audio but CW N thru the narrow filter slot. CW N will then go through the normal SSB filter.
If you need the exact jack number send me a direct email and I’ll look it up when I get a chance. I found it out when I was reversing the mod to use on CW. I later found it documented in the old Fox Tango newsletters, maybe May of 1985 or so.
73 de Chuck, WS1L ?
On Sat, Jan 22, 2022 at 5:38 PM ddelectrical via <ddelectrical= [email protected]> wrote: Hi Andrew. I noticed this too on an AM board I have here. I discovered it was done in the factory on later boards due to an earth problem causing hum if I remember right. Each section of the board receives its ground point individually with these tracks cut. Could have been an earth loop problem originally and cured by making the ground arrangement radial with the track cuts. The AM pcb fitted to my FT101ZD mk3 works with the tracks cut like this. It checks out on the schematic too.
After replacing my FM pcb with the AM one I then found that the audio bandwidth on AM is very narrow. It is necessary to fit a wide filter, (Yaesu XF-8.9GA), and modify the set to bypass the width control circuit to get the full 6kHz audio output. I have fitted the pcb and acquired a filter but have yet to do the mod to the width filter. This is a well known issue with the FT101ZD mk3. It may require fitting a toggle switch to the rear panel to switch the width control circuit in or out. I am still researching.
Hope this helps. Doesn't explain why yours is not working however.
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Re: FT-101ZD MK2 AM BOARD looks odd / modified???
Hi Andrew. I noticed this too on an AM board I have here. I discovered it was done in the factory on later boards due to an earth problem causing hum if I remember right. Each section of the board receives its ground point individually with these tracks cut. Could have been an earth loop problem originally and cured by making the ground arrangement radial with the track cuts. The AM pcb fitted to my FT101ZD mk3 works with the tracks cut like this. It checks out on the schematic too.
After replacing my FM pcb with the AM one I then found that the audio bandwidth on AM is very narrow. It is necessary to fit a wide filter, (Yaesu XF-8.9GA), and modify the set to bypass the width control circuit to get the full 6kHz audio output. I have fitted the pcb and acquired a filter but have yet to do the mod to the width filter. This is a well known issue with the FT101ZD mk3. It may require fitting a toggle switch to the rear panel to switch the width control circuit in or out. I am still researching.
Hope this helps. Doesn't explain why yours is not working however.
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FT-101ZD MK2 AM BOARD looks odd / modified???
Hello, I had a look at the AM board and it seems to have been modified ... Is that from factory and what is this for? AM doesn't work that's why I pulled the board. 73 
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Thanks ! I just wanted to be sure that the replacement fan I intend to use will be oriented the right way. ? 73, Jacques, VE2JFE in Montreal
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Hello,
The fan draws air out. So in other words it blows to the rear. This way the heat from the valves gets extracted from the case.
On Thu, 13 Jan 2022, 00:24 Bruce Collins, < kb0tj1@...> wrote: OUT.
As far as I know, cooling fans always draw fresh air in from somewhere and push it out at the fan side.
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Re: FT101E clarifier working when switched off
Hi Roger
Thank you. I have tried that with no success and no discernable change in the frequency either (swapped out D13 as well).???Whole thing is not making much sense to me at all!?
73 Grant
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Re: FT101E clarifier working when switched off
Hi Grant,
I would go back to the relay contacts again. Using a grounded probe jumper the C5 contact to ground. If that doesn't help ground the clarifier switch contact connected to D13.
73
Roger VE7LB
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FT101E clarifier working when switched off
Hello group (This also posted elsewhere)
After almost a 12 month postponement with a number of other more straightforward projects suddenly taking up bench space I'm back onto this elusive problem where the FT101E clarifier is working when it's turned off! The voltage swing at the VFO osc input is not as great as when its on, being about 0.35V. Compared to about 3.0V when clarifier switch is on (I really want to solve this because cosmetically this radio is in great condition and I've replaced the usual final cage suspect caps, the HV electrolytics and those on the regulator board). There remains just this one thing to resolve and I feel (after several hours) I have reached the limit of my knowledge in relation to what may be causing this. Thanks to many folk who have provided useful input to help me so far.
Here is what I have tested or tried but with no success -
- Checked relay grounding is sound
- Checked the clarifier push button switch is not faulty or intermittent
- Checked front panel VFO selector switch
- Swapped out Regulator/Calib module for known working one
- Swapped out Local Osc module for known working one
- Checked disc ceramic cap and diode (D13) wired directly onto clarifier switch/potentiometer
?
I don't know what to do next and would certainly appreciate any ideas please :)
Thank you
Grant
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Re: How does the 'Marker' signal actually work?
Ahh .. thank you ... I knew this project would be educational!
I initially assumed the 'Marker' would be an RF signal but then looked at the circuit and started to scratch my head!
25KHz to 14.2MHz is a lot of harmonics to go!
73,
M0KCR
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Re: How does the 'Marker' signal actually work?
Harmonics. The fundamental 25 kHz signal is typically a square wave that is rich in harmonics well up into the VHF region. That is also why the accuracy of the marker decreases as you go up in frequency. The error is multiplied as well. Anyone who has been around a while and had a .76 repeater in their area will remember the odd signal the used to be ubiquitous near 146.76. This was a harmonic of the 3.579545 MHz colorburst crystal used in analog color television sets and as a cheap master reference crystal in lots of consumer electronics (including at least one 2m HT). Not so common any more but it still can be found. This is also an object lesson in why our transmitters have harmonic filters. :) 73 -Jim NU0C On Sun, 16 Jan 2022 09:27:57 -0800 andrewhege33@... wrote: Hello,
I'm wondering how the Marker signal which seems to be a 25KHz NF signal actually leads to a signal 'received' on 14.2 MHz ...?
Any input appreciated
73
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How does the 'Marker' signal actually work?
Hello,
I'm wondering how the Marker signal which seems to be a 25KHz NF signal actually leads to a signal 'received' on 14.2 MHz ...?
Any input appreciated
73
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Re: FT-101ZD MK2 poor sensitivity ..
Hi Don,
I don't have a signal generator but a 4 channel digital scope.
I could buy a cheap QRP PIXIE as signal source or? use the marker signal and feed it back into the RX socket.
I've now measured the whole signal path and at least from a DC point of view the signal goes from the RX Antenna to the IF choke.
The resistance is about 1.5 ohm going from RX socket -> ATT SW -> Choke.
I will now use my scope to see what's going on RF wise ...
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Re: FT-101ZD MK2 poor sensitivity ..
If you don't have a generator, a piece of insulated wire hooked to your antenna and with the rig tuned to. 074, the FT 8 spot should be a usable reference for an injection probe.
Don ve3ids
On Sat., Jan. 15, 2022, 4:42 p.m. Don Richards, < ve3ids.don@...> wrote: Do you have a signal generator? If you do, inject a signal at the point where you have both the Red and Green Arrows marked and see if that is normal sensitivity. If it is, work back to the antenna connector and see where you are losing it.?
73 Don ve3ids
Reporting back ..
Removed both covers and traced the RX signal line via the ATT switch to Trimmer Board A.
I measured continuity between 'RX Antenna In' -> Switch -> choke and it was fine.
The switch is working as it should.
I also traced the marker signal and it is 'injected' before the choke together with the RX signal line.
 
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Re: FT-101ZD MK2 poor sensitivity ..
Do you have a signal generator? If you do, inject a signal at the point where you have both the Red and Green Arrows marked and see if that is normal sensitivity. If it is, work back to the antenna connector and see where you are losing it.?
73 Don ve3ids
Reporting back ..
Removed both covers and traced the RX signal line via the ATT switch to Trimmer Board A.
I measured continuity between 'RX Antenna In' -> Switch -> choke and it was fine.
The switch is working as it should.
I also traced the marker signal and it is 'injected' before the choke together with the RX signal line.
 
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Re: FT-101ZD MK2 poor sensitivity ..
Reporting back .. Removed both covers and traced the RX signal line via the ATT switch to Trimmer Board A. I measured continuity between 'RX Antenna In' -> Switch -> choke and it was fine. The switch is working as it should. I also traced the marker signal and it is 'injected' before the choke together with the RX signal line.  
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Chuck, WS1L
Bruce Collins
Jacques Fortin VE2JFE
Grant VK2LX
Jim Shorney
Don VE3IDS