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FT-101ZD MK2 poor sensitivity ..

 

I recently bought this boat anchor in very good condition.

I have not tested TX but the sensitivity of the RX side is quite weak..

I get the occasional broadcast station or HAM QSO but it's quite tone deaf.
The S-meter barely moves on receive.

It's not the 'bulb fuse' and I tested RX with the mark signal which gives me s9+20db in the meter reading.

Are there any usual culprits? I was thinking of starting by cleaning the switches / dials with an electrical contact cleaner since a
couple of them are somewhat scratchy.

Thank you 73, M0KCR
 

Others on here will know more but from my own recent investigations (see elsewhere also on here) the calibrator signal at that strength would appear to rule out the usual suspects of faulty RF/IF amplification devices (3SK51, J310 etc).? I bought my 101Z new 41 years ago and it has been a fantastic piece of equipment.? I have been looking for another one for some time now but with no success...? As and when you find out the nature of the fault I (and no doubt others) would be pleased to know what it was, how you identified it and how you rectified it.? Good luck.
Alistair GM4ENF
Nigel jones 2E0NJT
 

Hi Andrew,
although cleaning switches is always a good idea you would be better off applying a signal to the ant socket and measuring the receive sinad before you touch anything repair wise, you may find it only needs adjustment.
if you dont have the equipment to carry out such tests i would suggest getting someone else to check it and calibrate or repair it for you.
also be very careful if working on the inside of the unit with the case removed although the 900v rail is enclosed in the faraday cage there is still hundreds of volts available on the trimmer capacitors and several other places.
When working they are an excellent radio i have one im in the process of repairing myself.
 

Andrew?

You could try hooking your antenna to the receive antenna jack, the little one, not the so239 main antenna jack. This bypasses the antenna relay and lamp socket. If the calibrator gives you normal receive levels, there isn't much more from that point to the antenna jack.?

73 Don ve3ids

On Fri., Jan. 7, 2022, 2:27 p.m. , <andrewhege33@...> wrote:
I recently bought this boat anchor in very good condition.

I have not tested TX but the sensitivity of the RX side is quite weak..

I get the occasional broadcast station or HAM QSO but it's quite tone deaf.
The S-meter barely moves on receive.

It's not the 'bulb fuse' and I tested RX with the mark signal which gives me s9+20db in the meter reading.

Are there any usual culprits? I was thinking of starting by cleaning the switches / dials with an electrical contact cleaner since a
couple of them are somewhat scratchy.

Thank you 73, M0KCR
 

Well, the symptoms you describe are exactly what I see when I blow the lamp fuse, but I will assume you have checked it's continuity or otherwise confirmed it is OK.??

If you have the service manual, the diagrams showing signal flow in RX are very helpful.? Mine states the marker is injected right at the antenna terminal (page 2-1) and that a marker signal should be roughly 10 db over in SSB mode on 14.200 with the preselector peaked.??

The SSB/CW RX Mode signal flow on page 2-2 confirms this - the marker signal is injected before Q101 on the RF board.??

If the marker is that strong, then the fault SHOULD lie upstream of that point - page 2-8 states RF signal input 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.??

The marker output is on J504 Pin 2 of the AF board.? If your rig is after series 17, the new RF board is on page 5-8 of the manual but the pins look the same.

Bottom line best guess from here is a dirty RL2.? If not, then a dirty Attenuator switch on the lever switch board.??

YMMV.

Good luck, please let us know!



73 de Chuck, WS1L



On Fri, Jan 7, 2022 at 2:27 PM <andrewhege33@...> wrote:
I recently bought this boat anchor in very good condition.

I have not tested TX but the sensitivity of the RX side is quite weak..

I get the occasional broadcast station or HAM QSO but it's quite tone deaf.
The S-meter barely moves on receive.

It's not the 'bulb fuse' and I tested RX with the mark signal which gives me s9+20db in the meter reading.

Are there any usual culprits? I was thinking of starting by cleaning the switches / dials with an electrical contact cleaner since a
couple of them are somewhat scratchy.

Thank you 73, M0KCR
 

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
 

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

 

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
 

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.?
 

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 ...
 

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 ...
 

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
 

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
 

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
 

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

 

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

 

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

 

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@...
 

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)
?
?
 

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.

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