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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.
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

Re: FT-101ZD MK2 poor sensitivity ..

 

I had a look at the trimmer board A and I think the adjustable 'transformer' is T1 and not the trap coil (??).
There is also a 270pF capacitor which I think is C21 from the secondary side of the transformer.

As for the trap there is a large 1000pF capacitor on there which I think is C07.
However I can not see L01 unless it;s the small component between the trimmer and C07 I marked with ?
Or maybe I'm wrong altogether ..

What do you think?

FT101TrimmerA.jpg
FT101RX.jpg

Re: FT-101ZD MK2 poor sensitivity ..

 

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' :)

marker.mp4
marker.mp4

Re: FT-101ZD MK2 poor sensitivity ..

 

Well, let me try... Green line shows marker signal flow, from the block diagram it is injected outside of the RF Unit board but before Q101.

image.png

The marker circuit?is circled in red, the marker output in green:
image.png

The marker comes out of Pin 2 on Jack 4 of the AF board.? From there it should go into the RX chain, but the manual doesn't specify.? It only says it goes through relay RL2, lamp fuse FH2, attenuator switch 2004 on the lever switch board, 9 MHz trap L2101 and C1207 on the Trimmer A unit, then transformer T1 to Pin 3 of the RF board.??

So, a dirty relay could cause your symptoms.? Have you tried cleaning RL2???
Lamp fuse FH2 is tested and good, so that's not the problem.
ATT switch is another possible problem area, those switches are notorious for getting dirty.
C1207 (circled in red) doesn't look like its variable, so less likely it's a problem:
image.png

That leaves only 9 MHz trap L2101.? I'm not sure where that is, a 21 prefix should indicate the display board but that doesn't seem right.??

So, if you have cleaned out the ATT switch and the RL2 relay and still have the problem, that seems to only leave the fixed capacitor on the Trimmer A unit, the mystery 9 MHz trap wherever it is hiding, or something in the wiring harness between them all.

Hope this helps,

73 de Chuck, WS1L



On Wed, Jan 12, 2022 at 5:23 PM <andrewhege33@...> wrote:
Hello Chuck,

Following your post I went through the schematics and could retrace the RX signal flow (on paper).
So I now got a better understanding of the RX signal path.

Before I treat the switch with contact cleaner I will measure continuity between the antenna input and the IF-Trap which seems to be located on trimmer Board A.

Out of interest:
Could you shed some light on where the 'marker signal' is fed into the circuitry?

73, from the UK
Re: FT-101ZD Fan

 

OUT.
As far as I know, cooling fans always draw fresh air in from somewhere and push it out at the fan side.
Re: FT-101ZD MK2 poor sensitivity ..

 

The marker output is sent out from the AF board on J04 pin 2 which goes through trimmer A unit and on through T1 and on to the RF board.?

73 Don ve3ids

On Wed., Jan. 12, 2022, 5:23 p.m. , <andrewhege33@...> wrote:
Hello Chuck,

Following your post I went through the schematics and could retrace the RX signal flow (on paper).
So I now got a better understanding of the RX signal path.

Before I treat the switch with contact cleaner I will measure continuity between the antenna input and the IF-Trap which seems to be located on trimmer Board A.

Out of interest:
Could you shed some light on where the 'marker signal' is fed into the circuitry?

73, from the UK
Re: FT-101ZD MK2 poor sensitivity ..

 

Hello Chuck,

Following your post I went through the schematics and could retrace the RX signal flow (on paper).
So I now got a better understanding of the RX signal path.

Before I treat the switch with contact cleaner I will measure continuity between the antenna input and the IF-Trap which seems to be located on trimmer Board A.

Out of interest:
Could you shed some light on where the 'marker signal' is fed into the circuitry?

73, from the UK
FT-101ZD Fan

 

¿ªÔÆÌåÓý

Hi all,

?

A question about the FT-101ZD Cooling Fan.

Does it pushes the air in or out ??

?

73, Jacques, VE2JFE in Montreal
Re: FT-101ZD MK2 poor sensitivity ..

 

Hi Andrew,

That's good, it means that the problem is likely the attenuator switch like another op suggested. The relay and the lamp must be ok. I would try cleaning the attenuator switch like the other op described.?

73 Don ve3ids

On Tue., Jan. 11, 2022, 3:49 p.m. , <andrewhege33@...> wrote:
Hi Don,
Thank you ...
The problem arises on both inputs, same thing!
I also checked continuity between the two jacks and it was around 8 Ohm.

I used the 'Marker' switch too, dialed in the frequency and got S9 +20db on the scale.

The receiver works on the frequency shown in the display, I verified this when I received a faint broadcast station.

But basically the RX is really poor in picking up anything ...
Re: FT-101ZD MK2 poor sensitivity ..

 

Hi Don,
Thank you ...
The problem arises on both inputs, same thing!
I also checked continuity between the two jacks and it was around 8 Ohm.

I used the 'Marker' switch too, dialed in the frequency and got S9 +20db on the scale.

The receiver works on the frequency shown in the display, I verified this when I received a faint broadcast station.

But basically the RX is really poor in picking up anything ...
Re: FT-101ZD MK2 poor sensitivity ..

 

I¡¯ve had 2 out of the last four 101ZD radios... have similar issues after sitting around unused for too long.?
Get some decent switch cleaning spray like Deoxit D5.
Turn the radio face up and on it¡¯s back.
Go over to your attenuator switch and flip it down.?
Note there is a very tiny space behind the lever and at the thin felt dust cover where you can open it a bit with a needle.
Then push the Deoxit tube into the crack behind the lever bat and squirt a shot the Deoxit into the switch.?
Flip the lever up and down a dozen times and leave it in the up position.
Now do the exact same thing again with the switch up and use the needle again to move the felt dust cover a bit and shoot some Deoxit in again.
Flip the switch up and down another dozen times or so.?
There is a good chance you¡¯ll actually get a few drops of Deoxit in the switch and clean some crud out.?
Now reconnect the radio to your antenna and power.?
Find a band that should be active and adjust the RF gain to max, volume up a bit and tune the preselector to max background noise and listen around the band to see if cleaning the attenuator switch helped.?
Re: FT-101ZD MK2 poor sensitivity ..

 

The service manual is in the files area of this group.? I'll send you a copy of mine directly.??

GL,

73 de Chuck, WS1L



On Sun, Jan 9, 2022 at 6:08 PM <andrewhege33@...> wrote:
Thanks Chuck,

I need to get oriented with the schematics and the overall layout / functionality of the rig. It's quite a bit of components in there ...
It shouldn't be too difficult to trace the RF input signal. But unfortunately the bulb fuse is fine ;)

Which manual are you referring to ? I downloaded quite a few of them.

I removed the upper casing and the rig looks quite clean inside. It also has the optional CW filter it seems.

I couldn't get to the valves but they're all NEC.
73
Re: FT-101ZD MK2 poor sensitivity ..

 

You can do some easy initial checks without taking anything apart. Hook your receive antenna to the rcv ant jack and see if you get normal receive. If you do, check continuity, with power off, between the centre terminals of the main antenna jack to the rcv ant jack. You should have low resistance path here through the lamp and the antenna relay.?
Let us know the results and we can go from there.?

Best of luck
73 Don ve3ids

On Sun., Jan. 9, 2022, 6:08 p.m. , <andrewhege33@...> wrote:
Thanks Chuck,

I need to get oriented with the schematics and the overall layout / functionality of the rig. It's quite a bit of components in there ...
It shouldn't be too difficult to trace the RF input signal. But unfortunately the bulb fuse is fine ;)

Which manual are you referring to ? I downloaded quite a few of them.

I removed the upper casing and the rig looks quite clean inside. It also has the optional CW filter it seems.

I couldn't get to the valves but they're all NEC.
73

101_TOP.jpg
Screenshot_20220109-182900_Drive.jpg

Re: FT-101ZD MK2 poor sensitivity ..

 

Thanks Chuck,

I need to get oriented with the schematics and the overall layout / functionality of the rig. It's quite a bit of components in there ...
It shouldn't be too difficult to trace the RF input signal. But unfortunately the bulb fuse is fine ;)

Which manual are you referring to ? I downloaded quite a few of them.

I removed the upper casing and the rig looks quite clean inside. It also has the optional CW filter it seems.

I couldn't get to the valves but they're all NEC.
73
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