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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.
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
Re: FT-101ZD Fan

 

开云体育

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
Re: FT-101ZD Fan

 

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.

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
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
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
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
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
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
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 ...
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

On Sat., Jan. 15, 2022, 4:23 p.m. , <andrewhege33@...> wrote:
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.
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

On Sat., Jan. 15, 2022, 4:23 p.m. , <andrewhege33@...> wrote:
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.
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.
Re: Do I have to remove the VFO unit to replace the (VFO) bulbs?

 

Well, when you open it and look for yourself, the display unit is kind of in the way so for me it was A LOT easier to remove both the display unit and the four screws holding the VFO, then slide the VFO forward to get at the bulbs and holders.
Do I have to remove the VFO unit to replace the (VFO) bulbs?

 

As per subject line ...

Thank you
Re: FT-101ZD MK2 poor sensitivity ..

 

Yes, I was thinking about exactly this.
I'll have to wait for the Contact Cleaner to arrive, once it's here I'll open the radio and will inspect the switch.
Re: FT-101ZD MK2 poor sensitivity ..

 

Before going too far, try jumpering the attenuator switch.? That should localise the problem.

George, G8AOJ


On Thu, 13 Jan 2022 at 20:38, Chuck, WS1L <chandlerusm@...> wrote:
One thing you could try is to gently work the ATT switch back and forth like 50 times. That often works for a little time.?

On Thu, Jan 13, 2022 at 14:53 <andrewhege33@...> wrote:
Thank you for the effort Chuck,

The 'Trap' is located on the Trimmer Board 'A'

From my observation the Marker Signal does not go through the ATT switch but must be fed (as Don suggested) somewhere past it but before T1.

So that (as you said) would only leave the ATT switch or the 'trap'. Maybe a cold solder joint or wire that came 'off' ..

Well, at least I know where to look now and I've ordered 2 cans of contact cleaner.

Attached a video of the 'Marker' :)

--
Chuck Chandler chandlerusm@...



--
George Smith? - RSGB, Dean Forest Railway, H&GCT & Cotswold Canals Trust member
?
Tel:? 01594 835 736 (home)
?
?
Re: FT-101ZD MK2 poor sensitivity ..

 

One thing you could try is to gently work the ATT switch back and forth like 50 times. That often works for a little time.?

On Thu, Jan 13, 2022 at 14:53 <andrewhege33@...> wrote:
Thank you for the effort Chuck,

The 'Trap' is located on the Trimmer Board 'A'

From my observation the Marker Signal does not go through the ATT switch but must be fed (as Don suggested) somewhere past it but before T1.

So that (as you said) would only leave the ATT switch or the 'trap'. Maybe a cold solder joint or wire that came 'off' ..

Well, at least I know where to look now and I've ordered 2 cans of contact cleaner.

Attached a video of the 'Marker' :)

--
Chuck Chandler chandlerusm@...
Re: FT-101ZD MK2 poor sensitivity ..

 

The signal from the antenna connector followed the Red marks through the att switch and to the front end of the receiver. The marker is the Green mark which is injected after the att switch. With the marker working properly with the receiver, it is almost certain that it is just a dirty att switch. Everything must be working past the point where the paths join. My bet is just the att switch.?

73 Don ve3ids

On Thu., Jan. 13, 2022, 2:53 p.m. , <andrewhege33@...> wrote:
Thank you for the effort Chuck,

The 'Trap' is located on the Trimmer Board 'A'

From my observation the Marker Signal does not go through the ATT switch but must be fed (as Don suggested) somewhere past it but before T1.

So that (as you said) would only leave the ATT switch or the 'trap'. Maybe a cold solder joint or wire that came 'off' ..

Well, at least I know where to look now and I've ordered 2 cans of contact cleaner.

Attached a video of the 'Marker' :)

Screenshot_20220113-151855_Drive.jpg

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