B40 - Strange tuning knob? - UK Vintage Radio Repair and Restoration Discussion Forum

Nostaticatall · 20th Aug 2009, 9:41 am

I have a good old naval B40 receiver with a strange appendage! The tuning knob has a threaded rod sticking out of it. On close inspection it is moulded into the knob itself and is definitely there for a reason - but what purpose would it have served - remote motorised tuning maybe? Also the serial number on the plate has a line through it - what does that mean?

Steve

XTC · 20th Aug 2009, 10:42 am

I've no authoritative answers but my B40 also has the serial number barred and it looks as if the bar is painted in. It spent part of its life with the Sea Scouts. I'm just guessing, the bar means refurbished and checked out, still RN property, not current equipment. It appears to be a standard, unmodified, early B40. Cadet corps used to have HF radios (R107s etc) which were obsolete in the forces but which were still owned by HM government and maintained by the REME etc. Presumably, the original B40s were retired for cadet use while the later ones were still in service.

I don't know about the knob. Mine has a cranking handle for sweeping a range of the band quickly.

It could be that your set has a knob from something else, it could be that there was some other sort of rapid traversal attachment.

Pete.

Skywave · 20th Aug 2009, 9:32 pm

Interesting; OK, I'm guessing (again!)

-

I wonder if there was originally a flat bar attached - by means of a a tightly-fitting nut to that knob screw thread - and a spindle with a free-rotating bush / handle affixed to the other end of this flat bar - thus providing a means of rapid tuning, similar to that as described by Pete (XTC).

Moreover, is my eye-sight playing up or is that said thread a left-hand screw?

Al./ Skywave.

Nostaticatall · 21st Aug 2009, 1:30 pm

Thanks Pete and Al.

It's definitely a right hand thread - I can get a dexion type square nut on it which I think is 1/4" Whitworth.

The rapid tuning idea makes sense - I could imagine a small machine type wheel with a handle being attached, which would also explain why the stud is so long.

I was going to put a normal tuning knob on it but I'm kind of warming to its quirkiness.

Interestingly the set is all original with nothing replaced that I can see and it's as lively as a cricket up and down the bands. They don't build 'em like they used to!
Steve

Skywave · 21st Aug 2009, 2:36 pm

Quote:

Originally Posted by Nostaticatall

I was going to put a normal tuning knob on it but I'm kind of warming to its quirkiness.

They don't build 'em like they used to!

Steve

Mind that that protruding thread doesn't slowly grind a hole in your hand!

"Like they used to". Quite; including the weight!

Al.

XTC · 21st Aug 2009, 3:38 pm

I'd put a normal knob on. I can see that bare thread being a damned nuisance. Catching and tearing shirt sleeves, catching ankles if the set's on the floor and so on. If it caught your ankle, you might be tempted to kick the set - then you'd break your toes!

Pete.

AlanBeckett · 21st Aug 2009, 4:58 pm

Steve,
My B40C has a plain knob. I've never seen one like yours. On the subject of Serial Numbers all the ones I've seen had a line through them, including mine. I've always taken it to mean that they'de been 'scrapped' as far as the Navy were concerened ie no longer on their books.
Alan

Nostaticatall · 21st Aug 2009, 7:47 pm

Al and Pete
This is what I like about this forum, not just good technical knowledge and advice but concern for hands, ankles and toes

Yep, I think the stud has got to go, but not to protect the body parts you suggested - my eyesight is getting so bad, I have to get really close to the tuning scale nowadays...........

Steve

Nostaticatall · 21st Aug 2009, 7:48 pm

Quote:

Originally Posted by AlanBeckett

Steve,
On the subject of Serial Numbers all the ones I've seen had a line through them, including mine. I've always taken it to mean that they'de been 'scrapped' as far as the Navy were concerened ie no longer on their books.
Alan

That makes sense Alan - it's difficult to see any other reason for it.
Steve

Skywave · 21st Aug 2009, 9:57 pm

Quote:

Originally Posted by AlanBeckett

Steve,
I've always taken [a line through the serial number] to mean that they've been 'scrapped' - as far as the Navy were concerned - i.e. no longer 'on their books'.
Alan

'Off books', yes - but probably now doing another essential Naval Duty 'on hooks' - as a Boat Anchor!

Al. / Skywave.

AlanBeckett · 21st Aug 2009, 10:09 pm

Al,
Very droll

Alan

Nostaticatall · 21st Aug 2009, 10:16 pm

I thought the B40 was too heavy to be used as an anchor - they couldn't winch them back up.

Skywave · 21st Aug 2009, 11:19 pm

Well, there are some people - and I hasten to add that I am explicitly not one of them - who would ask "Why would you want to, anyway?"

Al. / Skywave.

XTC · 21st Aug 2009, 11:25 pm

Quote:

Originally Posted by Nostaticatall

Al and Pete
This is what I like about this forum, not just good technical knowledge and advice but concern for hands, ankles and toes

You are issued with two hands, two ankles, two eyes, ten fingers and ten toes, and one life. Crossed out serial numbers don't come into it. B40s? Well they're more durable and two ton should more than easily net you a good one, an excellent one; not true for the others mentioned and even if you secured one for the price there could be problems fitting the spare.

Murphy's law applies to shirts among other things. The more expensive the shirt, the more likely it is that you'll tear the sleeve out on the sticking out bit on the B40.

Pete.

QWENIX · 26th Aug 2009, 9:10 pm

As far as i can see this is a B40 or a B40A. These dont show up that often.

It could be used for lets say a kind of transmission box inverted a like techique.

Maybe this thread was used for an alternative transport protection. Heres a wild guess:

First dial for the frequency wanted. Then put he lever in lock position.

Next:
If you design a small cover rectangluar shape with a hole in the middle. This small cover would cover the dial knob and fit between the dialknob and the chrome handle at the base.

Put the cover on the dial knob (frequency still locked) and then use a nut to fix the cover on the shaft.

The frequency can never be changed only by taking if the cover and unlock the lever.

best regards,

Qwenix (Hoping you all understand my English)

20th Aug 2009, 9:41 am	#1
Nostaticatall Tetrode Join Date: Jan 2006 Location: Preston, Lancashire, UK. Posts: 62	B40 - Strange tuning knob? I have a good old naval B40 receiver with a strange appendage! The tuning knob has a threaded rod sticking out of it. On close inspection it is moulded into the knob itself and is definitely there for a reason - but what purpose would it have served - remote motorised tuning maybe? Also the serial number on the plate has a line through it - what does that mean? Steve Attached Thumbnails

20th Aug 2009, 10:42 am	#2
XTC Retired Dormant Member Join Date: Oct 2004 Location: Bristol, UK. Posts: 837	Re: B40 - Strange tuning knob? I've no authoritative answers but my B40 also has the serial number barred and it looks as if the bar is painted in. It spent part of its life with the Sea Scouts. I'm just guessing, the bar means refurbished and checked out, still RN property, not current equipment. It appears to be a standard, unmodified, early B40. Cadet corps used to have HF radios (R107s etc) which were obsolete in the forces but which were still owned by HM government and maintained by the REME etc. Presumably, the original B40s were retired for cadet use while the later ones were still in service. I don't know about the knob. Mine has a cranking handle for sweeping a range of the band quickly. It could be that your set has a knob from something else, it could be that there was some other sort of rapid traversal attachment. Pete.

20th Aug 2009, 9:32 pm	#3
Skywave Rest in Peace Join Date: Jun 2006 Location: Chard, South Somerset, UK. Posts: 7,457	Re: B40 - Strange tuning knob? Interesting; OK, I'm guessing (again!) - I wonder if there was originally a flat bar attached - by means of a a tightly-fitting nut to that knob screw thread - and a spindle with a free-rotating bush / handle affixed to the other end of this flat bar - thus providing a means of rapid tuning, similar to that as described by Pete (XTC). Moreover, is my eye-sight playing up or is that said thread a left-hand screw? Al./ Skywave.

21st Aug 2009, 1:30 pm	#4
Nostaticatall Tetrode Join Date: Jan 2006 Location: Preston, Lancashire, UK. Posts: 62	Re: B40 - Strange tuning knob? Thanks Pete and Al. It's definitely a right hand thread - I can get a dexion type square nut on it which I think is 1/4" Whitworth. The rapid tuning idea makes sense - I could imagine a small machine type wheel with a handle being attached, which would also explain why the stud is so long. I was going to put a normal tuning knob on it but I'm kind of warming to its quirkiness. Interestingly the set is all original with nothing replaced that I can see and it's as lively as a cricket up and down the bands. They don't build 'em like they used to! Steve

21st Aug 2009, 3:38 pm	#6
XTC Retired Dormant Member Join Date: Oct 2004 Location: Bristol, UK. Posts: 837	Re: B40 - Strange tuning knob? I'd put a normal knob on. I can see that bare thread being a damned nuisance. Catching and tearing shirt sleeves, catching ankles if the set's on the floor and so on. If it caught your ankle, you might be tempted to kick the set - then you'd break your toes! Pete.

21st Aug 2009, 4:58 pm	#7
AlanBeckett Rest in Peace Join Date: Dec 2008 Location: Burton upon Trent, East Staffordshire, UK. Posts: 1,686	Re: B40 - Strange tuning knob? Steve, My B40C has a plain knob. I've never seen one like yours. On the subject of Serial Numbers all the ones I've seen had a line through them, including mine. I've always taken it to mean that they'de been 'scrapped' as far as the Navy were concerened ie no longer on their books. Alan

21st Aug 2009, 7:47 pm	#8
Nostaticatall Tetrode Join Date: Jan 2006 Location: Preston, Lancashire, UK. Posts: 62	Re: B40 - Strange tuning knob? Al and Pete This is what I like about this forum, not just good technical knowledge and advice but concern for hands, ankles and toes Yep, I think the stud has got to go, but not to protect the body parts you suggested - my eyesight is getting so bad, I have to get really close to the tuning scale nowadays........... Steve

21st Aug 2009, 10:09 pm	#11
AlanBeckett Rest in Peace Join Date: Dec 2008 Location: Burton upon Trent, East Staffordshire, UK. Posts: 1,686	Re: B40 - Strange tuning knob? Al, Very droll Alan

21st Aug 2009, 10:16 pm	#12
Nostaticatall Tetrode Join Date: Jan 2006 Location: Preston, Lancashire, UK. Posts: 62	Re: B40 - Strange tuning knob? I thought the B40 was too heavy to be used as an anchor - they couldn't winch them back up.

21st Aug 2009, 11:19 pm	#13
Skywave Rest in Peace Join Date: Jun 2006 Location: Chard, South Somerset, UK. Posts: 7,457	Re: B40 - Strange tuning knob? Well, there are some people - and I hasten to add that I am explicitly not one of them - who would ask "Why would you want to, anyway?" Al. / Skywave.

26th Aug 2009, 9:10 pm	#15
QWENIX Pentode Join Date: Jan 2006 Location: Amsterdam, The Netherlands Posts: 180	Re: B40 - Strange tuning knob? As far as i can see this is a B40 or a B40A. These dont show up that often. It could be used for lets say a kind of transmission box inverted a like techique. Maybe this thread was used for an alternative transport protection. Heres a wild guess: First dial for the frequency wanted. Then put he lever in lock position. Next: If you design a small cover rectangluar shape with a hole in the middle. This small cover would cover the dial knob and fit between the dialknob and the chrome handle at the base. Put the cover on the dial knob (frequency still locked) and then use a nut to fix the cover on the shaft. The frequency can never be changed only by taking if the cover and unlock the lever. best regards, Qwenix (Hoping you all understand my English)