I am in the midst of restoring a Hallicrafters S-40A. I
think someone has changed the stop on the bandspread
capacitor. AFAIK all H receivers have the bandspread set at
0 and this represents minimum capacitance. On this RX 0 has
the bandspread cap completely closed and the frequency
calibration can not be brought in. If set at minimum it sets
up fine. There are other signs that the bandspread cap has
been fooled with.
I have seen one picture on the web which looks like the
dial pullies have been strung to correct a similar problem.
This is not what is shown in any of the S-40 series service
material. My question is: will someone confirm that the S-40
series bandspread cap should be at minimum with the dial at
0 and has anyone else encountered this problem?
The peg which forms the stop seems to be firm in its
socket. If its sticking out on the wrong side I may have to
restring the dial pullies to compensate. Thanks for any
help.


--

--
Richard Knoppow
Los Angeles
WB6KBL

Richard Knoppow wrote:
I am in the midst of restoring a Hallicrafters S-40A. I
think someone has changed the stop on the bandspread
capacitor. AFAIK all H receivers have the bandspread set at
0 and this represents minimum capacitance. On this RX 0 has
the bandspread cap completely closed and the frequency
calibration can not be brought in. If set at minimum it sets
up fine. There are other signs that the bandspread cap has
been fooled with.
I have seen one picture on the web which looks like the
dial pullies have been strung to correct a similar problem.
This is not what is shown in any of the S-40 series service
material. My question is: will someone confirm that the S-40
series bandspread cap should be at minimum with the dial at
0 and has anyone else encountered this problem?
The peg which forms the stop seems to be firm in its
socket. If its sticking out on the wrong side I may have to
restring the dial pullies to compensate. Thanks for any
help.

Short answer is yes, there's a mistake in some of the original
literature that had the dial going the wrong way. Its been a while so I
can't recall the specifics but it sounds as if you know the way to go
with it.

-Bill

"Bill M" wrote in message
...
Richard Knoppow wrote:
I am in the midst of restoring a Hallicrafters S-40A.
I think someone has changed the stop on the bandspread
capacitor. AFAIK all H receivers have the bandspread set
at 0 and this represents minimum capacitance. On this RX
0 has the bandspread cap completely closed and the
frequency calibration can not be brought in. If set at
minimum it sets up fine. There are other signs that the
bandspread cap has been fooled with.
I have seen one picture on the web which looks like
the dial pullies have been strung to correct a similar
problem. This is not what is shown in any of the S-40
series service material. My question is: will someone
confirm that the S-40 series bandspread cap should be at
minimum with the dial at 0 and has anyone else
encountered this problem?
The peg which forms the stop seems to be firm in its
socket. If its sticking out on the wrong side I may have
to restring the dial pullies to compensate. Thanks for
any help.

Short answer is yes, there's a mistake in some of the
original literature that had the dial going the wrong way.
Its been a while so I can't recall the specifics but it
sounds as if you know the way to go with it.

-Bill

Now I am confused, what is the "right" way? Should the
dial string cross over at any point? on the stuff I have
from the web its not shown that way.


--

--
Richard Knoppow
Los Angeles
WB6KBL

Is that the same as the S-40 (with out the A)? If so there is a stringing
diagram here on page 4:
http://www.nostalgiaair.org/PagesByM...7/M0008867.pdf

I hope this helps.

PP


"Richard Knoppow" wrote in message
m...
I am in the midst of restoring a Hallicrafters S-40A. I think someone
has changed the stop on the bandspread capacitor. AFAIK all H receivers
have the bandspread set at 0 and this represents minimum capacitance. On
this RX 0 has the bandspread cap completely closed and the frequency
calibration can not be brought in. If set at minimum it sets up fine.
There are other signs that the bandspread cap has been fooled with.
I have seen one picture on the web which looks like the dial pullies
have been strung to correct a similar problem. This is not what is shown
in any of the S-40 series service material. My question is: will someone
confirm that the S-40 series bandspread cap should be at minimum with the
dial at 0 and has anyone else encountered this problem?
The peg which forms the stop seems to be firm in its socket. If its
sticking out on the wrong side I may have to restring the dial pullies to
compensate. Thanks for any help.


--

--
Richard Knoppow
Los Angeles
WB6KBL

"Paul P" REMOVE paul @ REMOVE ppinyot . REMOVEcom wrote in
message ...
Is that the same as the S-40 (with out the A)? If so
there is a stringing diagram here on page 4:
http://www.nostalgiaair.org/PagesByM...7/M0008867.pdf

I hope this helps.

PP

My stuff snipped....

I think I have that info. All the service information I can
find on the web shows straight dial stringing but I have had
two replys indicating that some S-40 series require crossed
stringing. There must have been some manufacturing error or
change at some point but that info is probably lost. I will
change the stringing on my RX since I don't think I can get
the stop peg out without damaging the cap.


--

--
Richard Knoppow
Los Angeles
WB6KBL

"Richard Knoppow" wrote in
m:

I will
change the stringing on my RX since I don't think I can get
the stop peg out without damaging the cap.


I really don't see why you have a problem. All the bandspread cap does is
finetune a space around the center freq. To use it correctly, you leave it
set at 50, and then you can finetune either up or down. The stringing will
only affect which side is up or down. Obviously, you want less than 50 to
be down, so string it so it gains capacitance (lowers frequency) as you
tune down.

"elaich" wrote in message
...
"Richard Knoppow" wrote in
m:

I will
change the stringing on my RX since I don't think I can
get
the stop peg out without damaging the cap.


I really don't see why you have a problem. All the
bandspread cap does is
finetune a space around the center freq. To use it
correctly, you leave it
set at 50, and then you can finetune either up or down.
The stringing will
only affect which side is up or down. Obviously, you want
less than 50 to
be down, so string it so it gains capacitance (lowers
frequency) as you
tune down.

I think you don't understand the function of
bandspread. Even though this is not a calibrated bandspread
it does have definite position it must be in for the main
dial to be calibratable. For most Hallicrafters receivers
that is 0 on the dial representing minimum capacitance for
the band spread capacitor. The main dial will not calibrate
at any other value of capacitance. The trouble is that you
are suggesting a sort of makeshift which would prevent the
radio from working properly. The question is why was the
capacitor made in such a way that it could not work properly
if the dial stringing instructions for the receiver were
followed and why some receivers of this model are one way
and some another. Tha last two questions are probably beyond
answering. Its possible that some person wanted the
bandspread dial to start at 100 as it does for other brands
of receivers and delibrately changed the position of the
stop peg on the capacitor so that it rotates the wrong way.
Its also possible there was some change made in production
although I doubt that. In any case, since I have been unable
to knock the peg out to replace it the other way. I will
restring the dial system to reverse the rotation of the band
spread capacitor. That will have the cap at minimum value
when the dial indicates zero. The dial says on it to set at
0. So, even though I could simply calibrate it with the dial
at 100 the markings would mislead someone else trying to use
it.
While makeshifts are sometimes necessary I really hate
having to use them. Even the crossed stringing is a
makeshift but I am afraid of damaging the capacitor and
making the whole thing unusable if I apply too much force in
trying to remove the stop peg.


--

--
Richard Knoppow
Los Angeles
WB6KBL

Hello Richard:

I think I know what the problem is - but this is only a guess. Both you and
I have S-40A receivers where the bandspread capacitor has the lockout pin on
the wrong side of the retaining plate. They both appear to be factory jobs,
and the problem is that the receiver cannot be calibrated correctly.

In all cases, the restringing technique is the same for the S-40, the S-40A
and the S-40B.

I think the only logical conclusion is that Hallicrafters received a number
of capacitors that were manufactured defectively. They may have made them
themselves, which means that they would waste the money in remaking them.
Or, if a sub-contractor did it, they may have received a substantial price
break. In either case, Hallicrafters made the conscious decision to use
these defective capacitors and save money.

By stringing these capcaitors like you suggest, everything will operate
normally. And, there will not be a problem for years - or ever. I suspect
that in both of our receivers, the bandspread string broke and required
restringing. In both cases, the restringer strung it just as the service
instructions specified - which is why they do not work correctly. Since the
original change could not be observed (because the original string was
broken), the restringer would not know of the problem.

I think your solution is the only reasonable one. I suppose we should put a
note inside the receiver, so that in 30 years, when the string breaks again,
the same issue will not arise once more.

Perhaps we could put our S-40A receivers on eBay and advertise them as
unique or rare.

Glad you posted this, as I was beginning to think I had simply been working
on old radios far too long.

73, Colin K7FM

Also, I expect some bearing may be missing on your capacitor because someone
tried to "fix" it by the brute force method.

I was tempted to try the same method.

73, Colin K7FM