Topics

Racal RA17 lubrication


AllanIsaacs
 

I now have a third RA17 but it has a very heavy, rubbering feeling Mc/s knob and noisy Kc/s tuning.
The latter might be a vertical metal spindle top right that could be rubbing lettering on the filmstrip.
I sprayed switch cleaner into the Mc/s gearing but not much by way of improvement.
It appears that the front panel needs to come off for access.. something I've never tackled before.
Fortunately I bought a decent set of imperial Allen keys to remove knobs on my HP signal generator so those might be necessary.
Any advice before I get started ?
Allan G3PIY


Pete_G4GJL
 

Alan, is this a Mk2, an L or some other marque? This affects the answer to the kc/s tuning question.

The 'rubbery' feeling might be the tuning brake jammed ON. If i recall correctly, it should have a rubber stud at the contact point. After 50 years it could have deteriorated.

In addition to the above a basic checklist is:

Change any (all) Hunts PIOs on site.

Test all resistors as many will have gone high. NB.There is a potential divider between HT and GND in the 100kc/s IF

Silvered mica capacitors in the 37 and 40Mc/s filters occasionally fail. there is one manufacturer showing predominance for failure here....I cannot remember the manufacturer or the colour of the affected caps....someone here will!

Check the HT link is in place at the rear (HT1 links to HT2)

Soak the grub screws in the knobs with penetrating oil the night before you intend to remove them if they haven't been off for a few decades.

Good luck and keep us abreast of the project. There will be many of us with RACAL kit of that era on here!

73

Pete

On Tue, Sep 1, 2020 at 4:39 PM AllanIsaacs <allan@...> wrote:
I now have a third RA17 but it has a very heavy, rubbering feeling Mc/s knob and noisy Kc/s tuning.
The latter might be a vertical metal spindle top right that could be rubbing lettering on the filmstrip.
I sprayed switch cleaner into the Mc/s gearing but not much by way of improvement.
It appears that the front panel needs to come off for access.. something I've never tackled before.
Fortunately I bought a decent set of imperial Allen keys to remove knobs on my HP signal generator so those might be necessary.
Any advice before I get started ?
Allan G3PIY


AllanIsaacs
 

It’s a MkII Pete

I did try the tuning brake early on but I think its working OK. Once the front is off all should be revealed though.

I have had a silver mica fail in another example. I found it by wobbling the trimmers to see if all of them had an effect. One didn’t do anything and sure enough the associated capacitor was no good.

I bought a really good set of Allen keys to tackle an HP8640B with seized and mangled Allen screws and those worked fine…  no rust and the knobs just fell off without a struggle.

Hopefully the seized gearing means the set hasn’t seen too much use. I haven’t looked inside to see if any parts have already been replaced.

I intend to take a few pictures as work proceeds

73

Allan G3PIY


From: wireless-set-no19@groups.io [mailto:wireless-set-no19@groups.io] On Behalf Of Pete_G4GJL
Sent: 01 September 2020 18:46
To: wireless-set-no19@groups.io Notification
Subject: Re: [wireless-set-no19] Racal RA17 lubrication

 

Alan, is this a Mk2, an L or some other marque? This affects the answer to the kc/s tuning question.

 

The 'rubbery' feeling might be the tuning brake jammed ON. If i recall correctly, it should have a rubber stud at the contact point. After 50 years it could have deteriorated.

 

In addition to the above a basic checklist is:

 

Change any (all) Hunts PIOs on site.

 

Test all resistors as many will have gone high. NB.There is a potential divider between HT and GND in the 100kc/s IF

 

Silvered mica capacitors in the 37 and 40Mc/s filters occasionally fail. there is one manufacturer showing predominance for failure here....I cannot remember the manufacturer or the colour of the affected caps....someone here will!

 

Check the HT link is in place at the rear (HT1 links to HT2)

 

Soak the grub screws in the knobs with penetrating oil the night before you intend to remove them if they haven't been off for a few decades.

 

Good luck and keep us abreast of the project. There will be many of us with RACAL kit of that era on here!

 

73

 

Pete

 


Michael O'Beirne
 

 
Allan
 
I have removed quite a few RA17 panels.  The first thing is don’t panic! The job is a lot easier than removing the casting panel of an Eddystone 730/4.  That bloody thing needs four arms or a slave to help you.
 
1. Remove all the Berco knobs.  You only need two Allen keys for that.
 
2. Then unscrew the meter dolly switch.  It can dangle on its leads.  They are thick enough.
 
All the shaft switches and the BFO shaft are connected to modules and brackets on the chassis and pass through a hole in the panel.  They will stay in place when the panel is removed.
The two dolly switches on the bottom and the headphone sockets on the bottom row are connected to the chassis, not the panel, and pass through a large hole in the chassis, and you should leave them alone.
 
3. The speaker is fixed to the panel.  You will need to unsolder the leads from the guts to the speaker switch.
 
4. Then unscrew the chrome screws holding the panel to the chassis and side members.  Check whether the nuts are captive or (as on Collins gear) is an insert crimped to the chassis, or the bolts may screw into threaded holes in the chassis.
 
4. The panel will then come off. 
 
The full procedure should be described in the manual.  You will need the manual if you are going to do any serious work on the set.  I can lend you one if needs must.
 
One tip while the knobs are off.  If you want a heavier tuning knob, just fill the three internal cavities of the knob with external grade Pollyfilla – the stuff that looks like fine grey-brown sand.  Level the top with a steel edge while it is drying so that all cavities are equally full and the weight is symmetrical.   When dry it will stay in place – well, mine has for the last 20 years.  I have seen lead-filed ones too.
 
Email me direct if you come to grief.
 
73s
Michael
G8MOB
 
 
 

From: AllanIsaacs
Sent: Tuesday, September 1, 2020 4:30 PM
To: wireless-set-no19@groups.io
Subject: [wireless-set-no19] Racal RA17 lubrication
 
I now have a third RA17 but it has a very heavy, rubbering feeling Mc/s knob and noisy Kc/s tuning.
The latter might be a vertical metal spindle top right that could be rubbing lettering on the filmstrip.
I sprayed switch cleaner into the Mc/s gearing but not much by way of improvement.
It appears that the front panel needs to come off for access.. something I've never tackled before.
Fortunately I bought a decent set of imperial Allen keys to remove knobs on my HP signal generator so those might be necessary.
Any advice before I get started ?
Allan G3PIY
_._,_._,_


AllanIsaacs
 

OK Michael

All understood. My RS Pro imperial hex keys worked perfectly including the .05 one to detach the Mc/s bush.

I now have to read the manual (I have one somewhere) so I can refit all the bits. It looks like I’ll need to fire it up to check everything before the panel goes back on. I’ve never thought of adding weight to the tuning knob.. sounds like a good idea. Somewhere I have lots of lead fishing weights found with my metal detector. The local church roof is a non-starter as its been stripped so many times they now use something other than lead.

The panel came off really easily. I unscrewed the speaker. After cleaning and lubricating everything now runs freely. It was the two shafts on the chain drive that were the culprits. I had to slacken the scale to access the vertical metal idler whose bearings had dried and was very noisy. Hopefully the oil will do its stuff and make it quieter. I did once replace similar microscopic bearings for a local watchmaker in some electronic test gear that needed attention but I don’t fancy doing the same in the RA17. Not worth the hassle. Once the speaker is working or I’m wearing headphones the noise will hide the noisy from the bearings.

Just about to check the photos as they might help another RA17 owner.

73 Allan


From: wireless-set-no19@groups.io [mailto:wireless-set-no19@groups.io] On Behalf Of Michael O'Beirne via groups.io
Sent: 02 September 2020 10:32
To: wireless-set-no19@groups.io
Subject: Re: [wireless-set-no19] Racal RA17 lubrication

 

 

Allan

 

I have removed quite a few RA17 panels.  The first thing is don’t panic! The job is a lot easier than removing the casting panel of an Eddystone 730/4.  That bloody thing needs four arms or a slave to help you.

 

1. Remove all the Berco knobs.  You only need two Allen keys for that.

 

2. Then unscrew the meter dolly switch.  It can dangle on its leads.  They are thick enough.

 

All the shaft switches and the BFO shaft are connected to modules and brackets on the chassis and pass through a hole in the panel.  They will stay in place when the panel is removed.

The two dolly switches on the bottom and the headphone sockets on the bottom row are connected to the chassis, not the panel, and pass through a large hole in the chassis, and you should leave them alone.

 

3. The speaker is fixed to the panel.  You will need to unsolder the leads from the guts to the speaker switch.

 

4. Then unscrew the chrome screws holding the panel to the chassis and side members.  Check whether the nuts are captive or (as on Collins gear) is an insert crimped to the chassis, or the bolts may screw into threaded holes in the chassis.

 

4. The panel will then come off. 

 

The full procedure should be described in the manual.  You will need the manual if you are going to do any serious work on the set.  I can lend you one if needs must.

 

One tip while the knobs are off.  If you want a heavier tuning knob, just fill the three internal cavities of the knob with external grade Pollyfilla – the stuff that looks like fine grey-brown sand.  Level the top with a steel edge while it is drying so that all cavities are equally full and the weight is symmetrical.   When dry it will stay in place – well, mine has for the last 20 years.  I have seen lead-filed ones too.

 

Email me direct if you come to grief.

 

73s

Michael

G8MOB

 

 


Michael O'Beirne
 

Allan
 
A few extra points about that new RA17L.
 
The plastic Racal badge suggests late production.  That ties up with the excellent condition of the set.
 
Check the meter.  You know all about late production Ernest Turner meters.
 
73s
Michael
G8MOB
 
 


AllanIsaacs
 

It’s in fairly good condition Michael.. oodles better than my last one.

I managed to get it going before I fitted the front panel to check the position of the Mc/s gears. It was OK.

I did find however that I needed shims on the posts holding the chain gear chassis. I found 4 washers in the box of bits I’d removed so I guess they were used to move the chain clear of the rear wall. I noticed a dragging about half way through the tuning but once the washers were added it was very smooth.

During tests I noticed a burning smell and shortly afterwards the receiver changed from loud and clear to quiet and clear on stations.

I imagine its something like a screen decoupler gone very leaky and killed the resistor. Apart from that everything seems to work.

I’m a little unhappy with the alignment of the scale though.

It seems to drag on the rightmost pulley making a scratching noise. I did manage to re-tension the scale which I’d slackened off clean and lubricate the idler post.

I’m wondering if there’s a mechanical adjuster to make the scale run centrally and dead level? Maybe the tension is a bit slack?

It’s definitely a MkII not an “L” and there’s a NATO stock number on the back of the front panel. The PL239 isn’t an aerial socket. I tried it first but then moved to the male connector along the chassis.

Allan G3PIY


From: wireless-set-no19@groups.io [mailto:wireless-set-no19@groups.io] On Behalf Of Michael O'Beirne via groups.io
Sent: 02 September 2020 17:36
To: wireless-set-no19@groups.io
Subject: Re: [wireless-set-no19] Racal RA17 lubrication

 

Allan

 

A few extra points about that new RA17L.

 

The plastic Racal badge suggests late production.  That ties up with the excellent condition of the set.

 

Check the meter.  You know all about late production Ernest Turner meters.

 

73s

Michael

G8MOB

 

 

 


AllanIsaacs
 

I’m bashing on with my RA17 overhaul. It picks up Radio 4 and strong SSB on 40m but is a trifle deaf after a burning smell which lasted 10 minutes, the results of which I’ll try and track down later

It now seems it was rebuilt by Racal in 1976.

The Mc/s tuning feels OK now but the Kc/s tuning is noisy.

The noise seems to be the filmstrip rubbing on the lower edges of the two spools.

Is there a way of moving the sprocket wheel on the left maybe 0.5 to 1mm higher on its shaft?

That should result in the filmstrip lifting and not rubbing on the lower edges of the spools.

I can see what looks like a pin through the bush of the sprocket wheel plus a hex screw.

Allan G3PIY


Michael O'Beirne
 

Allan
 
Thanks for the update.  For an old MkII it is in extraordinary condition.  I am also surprised that it does not have a small black plate above the plastic escutcheon giving the
serial number, NSN, a date code for manufacture and its weight. These were fitted to the front panels of all military RA17s.   If it has been removed there would be two tell-tale 8BA holes about 2 inches apart.
 
My current guess is that it’s a new replacement panel.  That red plastic Racal badge is seen only on transistorised gear from about 1967 onwards.  Later gear from the mid 1970s had the logo sprayed on in black.
 
The SO239 socket is the IF Output at 100kHz.  It is wired in parallel with the Burndept one right beside it. There are two sockets because one might be connected to an ISB or FSK adaptor and the other to some form of spectrum display etc.   Each socket should be identified with a small metal plate screwed directly above the socket.  There was nothing cheap about this receiver!
 
To keep the cursor reasonable central you can slip the film off the drive sprocket carefully and move it left or right by a few “holes” till the reading you want is in the middle of the escutcheon.  You need to read the manual for the full procedure.  As I recall, you adjust the LO tracking at one end by adjusting a trimmer C at one end and the film position at the other end; not by adjusting the inductor.   Bear in mind that because of the multiple mixing, there is tuning inversion at the third LO so that the LO at 3.1kHz is scale 0 and 2.1kHz is 1000.  Read the manual before you even think about realignment. 
 
Talking about the cursor here is another tip.  The present one is thick wire.  It’s soldered to the adjustor.  I removed it and replaced it with an inch of enamelled copper wire of about 24SWG. This improved reading the scale.
 
Another reversible mod is to replace the existing 6V lamp with a string of white LEDs or mini long life bulbs mounted on a strip of paxolin etc the width of the 6 inch escutcheon slot with a thin white diffuser behind the scale to give a more even illumination.  You will need to make a DC supply for the LEDs.  This will also reduce the glare. On one of my RA17s the previous owner had fitted mini bulbs behind a green sheet of plastic.  The black numbers are still black and the red scale is now magenta but the contrast is much better and ideal for my crappy eyes.  I think that owner had similarly bad eyesight.  Purists will wince at this but if the set is to be in regular use you might as well make life a tad easier. 
 
I’ll search for my mod to convert the AF section of the meter to a proper S meter.  It’s based on that fitted to the RA17C-12 and RA117.  On my receiver, S9 is at about 130 on the 0-200 scale.  It’s a standard balanced bridge circuit and will prevent the meter pinging to endstop with the BFO on.
 
73s
Michael
G8MOB
 
 

From: AllanIsaacs
Sent: Wednesday, September 2, 2020 6:14 PM
To: wireless-set-no19@groups.io
Subject: Re: [wireless-set-no19] Racal RA17 lubrication
 

It’s in fairly good condition Michael.. oodles better than my last one.

I managed to get it going before I fitted the front panel to check the position of the Mc/s gears. It was OK.

I did find however that I needed shims on the posts holding the chain gear chassis. I found 4 washers in the box of bits I’d removed so I guess they were used to move the chain clear of the rear wall. I noticed a dragging about half way through the tuning but once the washers were added it was very smooth.

During tests I noticed a burning smell and shortly afterwards the receiver changed from loud and clear to quiet and clear on stations.

I imagine its something like a screen decoupler gone very leaky and killed the resistor. Apart from that everything seems to work.

I’m a little unhappy with the alignment of the scale though.

It seems to drag on the rightmost pulley making a scratching noise. I did manage to re-tension the scale which I’d slackened off clean and lubricate the idler post.

I’m wondering if there’s a mechanical adjuster to make the scale run centrally and dead level? Maybe the tension is a bit slack?

It’s definitely a MkII not an “L” and there’s a NATO stock number on the back of the front panel. The PL239 isn’t an aerial socket. I tried it first but then moved to the male connector along the chassis.

Allan G3PIY


Michael O'Beirne
 

Allan
 
Interesting that the set may have been rebuilt by Racal.  That would explain a lot.
 
I have never encountered your rubbing problem. I can’t find anything in the manual dealing with that it. You may have to be brave and adjust the sprocket wheel’s height. I hope that does not require removal of the film scale.  That’s a fiddly job.
 
73s
Michael
G8MOB
 

From: AllanIsaacs
Sent: Thursday, September 3, 2020 11:27 AM
To: wireless-set-no19@groups.io
Subject: Re: [wireless-set-no19] Racal RA17 lubrication
 

I’m bashing on with my RA17 overhaul. It picks up Radio 4 and strong SSB on 40m but is a trifle deaf after a burning smell which lasted 10 minutes, the results of which I’ll try and track down later

It now seems it was rebuilt by Racal in 1976.

The Mc/s tuning feels OK now but the Kc/s tuning is noisy.

The noise seems to be the filmstrip rubbing on the lower edges of the two spools.

Is there a way of moving the sprocket wheel on the left maybe 0.5 to 1mm higher on its shaft?

That should result in the filmstrip lifting and not rubbing on the lower edges of the spools.

I can see what looks like a pin through the bush of the sprocket wheel plus a hex screw.

Allan G3PIY

_._,_._,_


Don_Vosper
 

Hi
Looks to  me like a major engineering job to  move the sprocket. That probably isn't the problem.
I freed up  the bearings and checked mine and it was still noisy.
I have a spare front panel  and that has a plastic Racal  badge.
If you want an enamel  one they are available, or were recently, on ebay for £14.00.
Don


AllanIsaacs
 

Hi Don
I think I found part of the problem. The bearing on top of the vertical Kc/s
tuning shaft was too tight and packed with black putty that I guess used to
be grease.
I had a job slackening the nut but managed eventually and adjusted the thing
so it has no discernible end float. The lower bearing is probably OK as I
dripped oil onto it and gravity did the rest. The tuning knob now spins
freely and the noise has lessened.
The badge is fine. I don't mind the newer one as it's consistent with the
history of the receiver.
All the resistors under the main chassis seem OK but there are loads of
tubular condensers that probably need swapping. It has metal finned power
resistors.
If the thing wasn't so heavy I'd fit new capacitors straight away.
73 Allan G3PIY

-----Original Message-----
From: wireless-set-no19@groups.io [mailto:wireless-set-no19@groups.io] On
Behalf Of Don_Vosper via groups.io
Sent: 03 September 2020 13:12
To: wireless-set-no19@groups.io
Subject: [wireless-set-no19] Racal RA17 lubrication

Hi
Looks to  me like a major engineering job to  move the sprocket. That
probably isn't the problem.
I freed up  the bearings and checked mine and it was still noisy.
I have a spare front panel  and that has a plastic Racal  badge.
If you want an enamel  one they are available, or were recently, on ebay
for £14.00.
Don


Pete_G4GJL
 

Michael, I too would be interested in having the S-meter mod info, if and when you find it.
 
Pete
G4GJL

On Thu, 3 Sep 2020 at 12:18, Michael O'Beirne via groups.io <michaelob666=ntlworld.com@groups.io> wrote:

Allan

Thanks for the update.  For an old MkII it is in extraordinary condition.  I am also surprised that it does not have a small black plate above the plastic escutcheon giving the serial number, NSN, a date code for manufacture and its weight. These were fitted to the front panels of all military RA17s.   If it has been removed there would be two tell-tale 8BA holes about 2 inches apart.

My current guess is that it’s a new replacement panel.  That red plastic Racal badge is seen only on transistorised gear from about 1967 onwards.  Later gear from the mid 1970s had the logo sprayed on in black.
The SO239 socket is the IF Output at 100kHz.  It is wired in parallel with the Burndept one right beside it. There are two sockets because one might be connected to an ISB or FSK adaptor and the other to some form of spectrum display etc.   Each socket should be identified with a small metal plate screwed directly above the socket.  There was nothing cheap about this receiver!

To keep the cursor reasonable central you can slip the film off the drive sprocket carefully and move it left or right by a few “holes” till the reading you want is in the middle of the escutcheon.  You need to read the manual for the full procedure.  As I recall, you adjust the LO tracking at one end by adjusting a trimmer C at one end and the film position at the other end; not by adjusting the inductor.   Bear in mind that because of the multiple mixing, there is tuning inversion at the third LO so that the LO at 3.1kHz is scale 0 and 2.1kHz is 1000.  Read the manual before you even think about realignment.

Talking about the cursor here is another tip.  The present one is thick wire.  It’s soldered to the adjustor.  I removed it and replaced it with an inch of enamelled copper wire of about 24SWG. This improved reading the scale.

Another reversible mod is to replace the existing 6V lamp with a string of white LEDs or mini long life bulbs mounted on a strip of paxolin etc the width of the 6 inch escutcheon slot with a thin white diffuser behind the scale to give a more even illumination.  You will need to make a DC supply for the LEDs.  This will also reduce the glare. On one of my RA17s the previous owner had fitted mini bulbs behind a green sheet of plastic.  The black numbers are still black and the red scale is now magenta but the contrast is much better and ideal for my crappy eyes.  I think that owner had similarly bad eyesight.  Purists will wince at this but if the set is to be in regular use you might as well make life a tad easier.

I’ll search for my mod to convert the AF section of the meter to a proper S meter.  It’s based on that fitted to the RA17C-12 and RA117.  On my receiver, S9 is at about 130 on the 0-200 scale.  It’s a standard balanced bridge circuit and will prevent the meter pinging to endstop with the BFO on.

73s
Michael
G8MOB


Don_Vosper
 

Alan
A clue I have found with burning smells is to  look at the RF chokes in the HT lines.
The chokes warm up and sometime discolour so  give you an idea as to  the locatiomn of the dodgy component.
Don


G0OZS
 

Allan, Michael

 

On a related issue I have an RA17 that belonged to an SK retired work colleague waiting for attention. I’m told by his XYL that it was in use until his health failed about 4 years ago, so I’m not sure how much in the way of component replacement will be needed yet.

 

The known fault with this set is that the film tuning scale does not always move when the KHz  knob is turned. I have noticed that I have to pull the knob slightly outwards in order for it to work reliably. This is clearly a mechanical rather than an electronic issue – is it something you (or any other reader) have experienced and if so is there a simple cure ? (I do have thoughts of a rubber grommet behind the knob to provide outward pressure as an interim solution, until I have time to do a full disassembly)

 

Iain

73 de G0OZS

 

 


Michael O'Beirne
 

Iain
 
The mechanics of the Kc/s tuning are very robust and unlikely to be faulty.  My starting point would be to check the bearings for dried up lubrication in the area of the film scale.  Undo the small metal covers over the bearings and add a bit of solvent to soften the old lube.  Clean up with cotton buds and replace with a bit of Molyslip.  It used to come in tubes. 
 
73s
Michael
G8MOB
 

From: G0OZS
Sent: Thursday, September 3, 2020 9:34 PM
To: wireless-set-no19@groups.io
Subject: Re: [wireless-set-no19] Racal RA17 lubrication
 

Allan, Michael

 

On a related issue I have an RA17 that belonged to an SK retired work colleague waiting for attention. I’m told by his XYL that it was in use until his health failed about 4 years ago, so I’m not sure how much in the way of component replacement will be needed yet.

 

The known fault with this set is that the film tuning scale does not always move when the KHz  knob is turned. I have noticed that I have to pull the knob slightly outwards in order for it to work reliably. This is clearly a mechanical rather than an electronic issue – is it something you (or any other reader) have experienced and if so is there a simple cure ? (I do have thoughts of a rubber grommet behind the knob to provide outward pressure as an interim solution, until I have time to do a full disassembly)

 

Iain

73 de G0OZS

 

 

_._,_._,_


AllanIsaacs
 

Hi Iain

I wonder if it’s just that the hex bolt in the centre of the tuning knob isn’t tight enough?

I found that at the 100 end of the 1000KHz scale there’s less force needed to move the filmstrip than the 900 end so at some point the knob might slip.

If the set actually tunes but the scale is stationary then you need to rotate the front take-up spool (with the idler gear disengaged) to increase filmstrip tension.

Allan G3PIY


From: wireless-set-no19@groups.io [mailto:wireless-set-no19@groups.io] On Behalf Of G0OZS
Sent: 03 September 2020 21:34
To: wireless-set-no19@groups.io
Subject: Re: [wireless-set-no19] Racal RA17 lubrication

 

Allan, Michael

 

On a related issue I have an RA17 that belonged to an SK retired work colleague waiting for attention. I’m told by his XYL that it was in use until his health failed about 4 years ago, so I’m not sure how much in the way of component replacement will be needed yet.

 

The known fault with this set is that the film tuning scale does not always move when the KHz  knob is turned. I have noticed that I have to pull the knob slightly outwards in order for it to work reliably. This is clearly a mechanical rather than an electronic issue – is it something you (or any other reader) have experienced and if so is there a simple cure ? (I do have thoughts of a rubber grommet behind the knob to provide outward pressure as an interim solution, until I have time to do a full disassembly)

 

Iain

73 de G0OZS

 


AllanIsaacs
 

I seem to have done something really bad…

I happened to spin the Kc/s tuning knob and the scale went past the STOP warning.

There was a clunk and the tuning knob/shaft locked in place.

At the side of the gearbox there’s a slot in which is the square end of a metal bar.

Turning the knob makes the bar bump against the top or bottom of the slot

I detached the front of the gearbox complete with bearing but there’s nothing to help.

Surely I’m not the first to get into this pickle??

Allan G3PIY


Pete_G4GJL
 

Friction is holding this bar (the stop mechanism) against the ice flywheel 
 
Pete
G4GJL

On Fri, 4 Sep 2020 at 16:10, AllanIsaacs <allan@...> wrote:

I seem to have done something really bad…

I happened to spin the Kc/s tuning knob and the scale went past the STOP warning.

There was a clunk and the tuning knob/shaft locked in place.At the side of the gearbox there’s a slot in which is the square end of a metal bar. Turning the knob makes the bar bump against the top or bottom of the slot.  I detached the front of the gearbox complete with bearing but there’s

nothing to help.


Surely I’m not the first to get into this pickle??

Allan G3PIY


AllanIsaacs
 

Thanks Pete

When I heard the loud clunk I thought something nasty had happened.

I needed to use a long Allen Key as a lever in one of the holes in the outer edge of the flywheel to free it up.

What had happened is so obvious once you realise that bar slides in the slot to fix tuning limits and scale movement.

Receivers have numerous methods to limit tuning range especially when fitted with a flywheel. My DST100 had a mechanical fault in that area that kept me guessing. It was sticky lubrication (again) to blame in not releasing a plunger. It freed up at snails pace so you accidentally ended up stuck beyond the tuning limit.

73 Allan G3PIY


From: wireless-set-no19@groups.io [mailto:wireless-set-no19@groups.io] On Behalf Of Pete_G4GJL
Sent: 04 September 2020 17:27
To: wireless-set-no19@groups.io
Subject: Re: [wireless-set-no19] Racal RA17 lubrication

 

Friction is holding this bar (the stop mechanism) against the ice flywheel 

 

Pete

G4GJL

 

On Fri, 4 Sep 2020 at 16:10, AllanIsaacs <allan@...> wrote:

I seem to have done something really bad…

I happened to spin the Kc/s tuning knob and the scale went past the STOP warning.

There was a clunk and the tuning knob/shaft locked in place.At the side of the gearbox there’s a slot in which is the square end of a metal bar. Turning the knob makes the bar bump against the top or bottom of the slot.  I detached the front of the gearbox complete with bearing but there’s

nothing to help.

 

Surely I’m not the first to get into this pickle??

Allan G3PIY