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K3 - REF CAL Question

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Dave, G4AON

K3 - REF CAL Question

Bud, this one crops up from time to time, unfortunately Elecraft haven't
yet implemented the higher stability TCXO calibration routine... So you
can't calibrate it better than 1ppm.

The technical menu needs to be turned on in order to view the PA temp, etc.

73 Dave, G4AON
K3/100 #80
----------------

I don't seem to be able to get my K3 to go from REF CAL to REF xxC. Tapping
the 1 just changes from A to B. I have the latest firmware and I can't find
anywhere I'm supposed to tell the firmware that I have the 1 ppm oscillator.
Can anyone tell me what I'm missing?
<SNIP>
73, Bud N7CW

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Bud Semon N7CW

RE: K3 - REF CAL Question

Dave and Glenn (ON4WIX),

Thanks - the TECH MD worked. The errata sheet that came with my Owner's
Manual referred to an update to the REF CAL procedure in a future firmware
update and I assumed that it was included in the latest. So much for
assuming :) I'll keep my eyes on the reflector...

73 and CU on the bands.

Bud N7CW

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Dave G4AON
Sent: Monday, June 16, 2008 12:08 PM
To: [hidden email]
Subject: [Elecraft] K3 - REF CAL Question

Bud, this one crops up from time to time, unfortunately Elecraft haven't
yet implemented the higher stability TCXO calibration routine... So you
can't calibrate it better than 1ppm.

The technical menu needs to be turned on in order to view the PA temp, etc.

73 Dave, G4AON
K3/100 #80
----------------

I don't seem to be able to get my K3 to go from REF CAL to REF xxC. Tapping
the 1 just changes from A to B. I have the latest firmware and I can't find
anywhere I'm supposed to tell the firmware that I have the 1 ppm oscillator.
Can anyone tell me what I'm missing?
<SNIP>
73, Bud N7CW

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Paul-285

Re: K3 - REF CAL Question

In reply to this post by Dave, G4AON

>The technical menu needs to be turned on in order to view the PA temp, etc.

How do you switch the temperatures to Fahrenheit?

Paul N4LCD

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N5GE

Re: K3 - REF CAL Question

On Tue, 17 Jun 2008 10:42:53 -0400, [hidden email] wrote:

>
>
>
>>The technical menu needs to be turned on in order to view the PA temp, etc.
>
>How do you switch the temperatures to Fahrenheit?
>
>Paul N4LCD
>

[snip]

You can't. You have to do the calculation shown on page 51 of the owner's
manual in the FP TEMP section.

73,

Tom, N5GE - SWOT 3537 - Grid EM12jq

"Those who would give up
Essential Liberty to
purchase a little Temporary
Safety deserve neither
Liberty nor Safety"

An excerpt from a letter
written in 1755 from the
Assembly to the Governor
of Pennsylvania.

Support the entire Constitution, not
just the parts you like.

http://www.n5ge.com
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Amateur Radio Operator N5GE

michael taylor-3

Re: K3 - REF CAL Question

On Tue, Jun 17, 2008 at 12:12 PM, Tom Childers, N5GE <[hidden email]> wrote:
> On Tue, 17 Jun 2008 10:42:53 -0400, [hidden email] wrote:
>>
>>How do you switch the temperatures to Fahrenheit?
>>
>>Paul N4LCD

I think transistors work in Celsius, while vacuum tubes / valves work
in Fahrenheit. :-)

(As far as I know, Tom is right, good old fashion arithmetic is required)

-Michael, VE3TIX
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Don Wilhelm-4

Re: K3 - REF CAL Question

In reply to this post by Paul-285

Paul,

You have to do that with your calculator :-) .
I never can remember when to add 32 and when to subtract 32, so I use a
slightly different method which relies on the fact that both the F and C
scales coincide at -40 deg.
Add 40 first - then multiply by 5/9 (multiply by 5 and divide by 9) if
converting from F to C (9/5 when converting from C to F), then subtract
40 and you will have the converted result. Remembering whether to use
5/9 or 9/5 is easy too - if the result you want is the C scale, the
number will be smaller, so use 5/9. When the result is in deg F, the
number must be larger, so use 9/5.

73,
Don W3FPR

[hidden email] wrote:

>
>
>
>> The technical menu needs to be turned on in order to view the PA
>> temp, etc.
>
> How do you switch the temperatures to Fahrenheit?
>
> Paul N4LCD
>

KK7P

Re: K3 - REF CAL Question

> You have to do that with your calculator :-)

C to F is fast and easy to do in your head.

The "real" formula is:

F = (1.8 * C) + 32

My mental algorithm is:

double the value,
subtract 10% (round it off, who cares if it is a degree or two off),
add 30,
then add 2 (if you feel the need for the extra precision).

Most of us can double a number in our head pretty easily. Round it to
the nearest 5 and then double it if you have trouble doubling 37 or 43
or 51. Hey! It's just the "two times" tables, which we all learned well
before our 9th birthday.

Doubling and then taking off 10% of the result is the same as
multiplying by 1.8 (or 9/5 if you prefer) but a heckuva lot easier. I
never did learn my "1.8 times" tables...

Again, round it if you trip over something like 74 - 7.4. The answer is
66.6. But does it really matter if you decide to subtract 10 and get
64? Or subtract 7 and get 67?

Subtract 30 then 2 rather than 32. Why? Because it is easier to not
deal with the 1's digit until you have to. If you feel you have to.

I find that I can usually work it out in my head in under a second and
get within a few degrees of the "correct" result. Near enough for most
needs. If I'm tired it might take 2 or even 3 seconds to make the
conversion, especially if I refuse to round things off (being an
engineer, I sometimes get anal about numbers, which is a good indicator
I'm tired!).

So, for example, let's take 52C. Is the PA too hot?

The real method:

2 x 52 = 104.
104 - 10.4 = 94 (near enough)
94 + 30 = 124
124 + 2 = 126(if you really care...)

If you'd rounded it:

2 x 50 = 100
100 - 10 = 90
90 + 30 = 120
120 + 2 = 122.

Still close enough to decide if your finals are cooking! (They aren't).
Would the 4 degree difference have made you change you mind about the
safety of your PA transistors? I doubt it.

F to C is much slower, but I rarely have to do that :-)

Enjoy!

Lyle KK7P

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Lou Aguilar

Re: K3 - REF CAL Question

In reply to this post by Don Wilhelm-4

Google works great for this:

Fahrenheit to Celsius

90f in c

Celsius to F:

23c in f

On Jun 17, 2008, at 4:38 PM, Don Wilhelm wrote:

> Paul,
>
> You have to do that with your calculator :-) .
> I never can remember when to add 32 and when to subtract 32, so I
> use a slightly different method which relies on the fact that both
> the F and C scales coincide at -40 deg.
> Add 40 first - then multiply by 5/9 (multiply by 5 and divide by 9)
> if converting from F to C (9/5 when converting from C to F), then
> subtract 40 and you will have the converted result. Remembering
> whether to use 5/9 or 9/5 is easy too - if the result you want is
> the C scale, the number will be smaller, so use 5/9. When the
> result is in deg F, the number must be larger, so use 9/5.
>
> 73,
> Don W3FPR
>
> [hidden email] wrote:
>>
>>
>>
>>> The technical menu needs to be turned on in order to view the PA
>>> temp, etc.
>>
>> How do you switch the temperatures to Fahrenheit?
>>
>> Paul N4LCD
>>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
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KK7P

Re: K3 - REF CAL Question

In reply to this post by KK7P

> Subtract 30 then 2 rather than 32.

Add 30 then 2... It was a test...

73,

Lyle KK7P

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Don Wilhelm-4

Re: K3 - REF CAL Question

In reply to this post by KK7P

I will still use F = (1.8 * (C+40)) - 40 -- as I said, I have more
trouble remembering whether to add or subtract the 32.
Similarly, C = (F+40)/1.8 -40, so it is not so complicated after all.
Dividing by 1.8 is similarly easy to do in the head - divide by 2 and
then add 10% of the result - it is not exact, but close enough for
'government work'.

73,
Don W3FPR

Lyle Johnson wrote:

>> You have to do that with your calculator :-)
>
> C to F is fast and easy to do in your head.
>
> The "real" formula is:
>
> F = (1.8 * C) + 32
>
> My mental algorithm is:
>
> double the value,
> subtract 10% (round it off, who cares if it is a degree or two off),
> add 30,
> then add 2 (if you feel the need for the extra precision).
>
> Most of us can double a number in our head pretty easily. Round it to
> the nearest 5 and then double it if you have trouble doubling 37 or 43
> or 51. Hey! It's just the "two times" tables, which we all learned
> well before our 9th birthday.
>
> Doubling and then taking off 10% of the result is the same as
> multiplying by 1.8 (or 9/5 if you prefer) but a heckuva lot easier.
> I never did learn my "1.8 times" tables...
>
> Again, round it if you trip over something like 74 - 7.4. The answer
> is 66.6. But does it really matter if you decide to subtract 10 and
> get 64? Or subtract 7 and get 67?
>
> Subtract 30 then 2 rather than 32. Why? Because it is easier to not
> deal with the 1's digit until you have to. If you feel you have to.
>
> I find that I can usually work it out in my head in under a second and
> get within a few degrees of the "correct" result. Near enough for
> most needs. If I'm tired it might take 2 or even 3 seconds to make
> the conversion, especially if I refuse to round things off (being an
> engineer, I sometimes get anal about numbers, which is a good
> indicator I'm tired!).
>
> So, for example, let's take 52C. Is the PA too hot?
>
> The real method:
>
> 2 x 52 = 104.
> 104 - 10.4 = 94 (near enough)
> 94 + 30 = 124
> 124 + 2 = 126(if you really care...)
>
> If you'd rounded it:
>
> 2 x 50 = 100
> 100 - 10 = 90
> 90 + 30 = 120
> 120 + 2 = 122.
>
> Still close enough to decide if your finals are cooking! (They
> aren't). Would the 4 degree difference have made you change you mind
> about the safety of your PA transistors? I doubt it.
>
> F to C is much slower, but I rarely have to do that :-)
>
> Enjoy!
>
> Lyle KK7P
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
> ------------------------------------------------------------------------
>
>
> No virus found in this incoming message.
> Checked by AVG.
> Version: 8.0.100 / Virus Database: 270.3.0/1505 - Release Date: 6/16/2008 7:20 AM
>

Joe Subich, W4TV-3

RE: K3 - REF CAL Question

In reply to this post by KK7P

> F to C is much slower,

Not really ... (F - 30)/2 is generally within 10% and
(F - 32) * 1.1 / 2 is within about 1%. Both are easy/quick.

Unfortunately, mental math and estimation are skills that have
been lost with the "calculator generation."

73,

... Joe, W4TV

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Lyle Johnson
> Sent: Tuesday, June 17, 2008 5:14 PM
> To: [hidden email]
> Cc: [hidden email]; [hidden email]
> Subject: Re: [Elecraft] K3 - REF CAL Question
>
>
> > You have to do that with your calculator :-)
>
> C to F is fast and easy to do in your head.
>
> The "real" formula is:
>
> F = (1.8 * C) + 32
>
> My mental algorithm is:
>
> double the value,
> subtract 10% (round it off, who cares if it is a degree or two off),
> add 30,
> then add 2 (if you feel the need for the extra precision).
>
> Most of us can double a number in our head pretty easily.
> Round it to
> the nearest 5 and then double it if you have trouble doubling
> 37 or 43
> or 51. Hey! It's just the "two times" tables, which we all
> learned well
> before our 9th birthday.
>
> Doubling and then taking off 10% of the result is the same as
> multiplying by 1.8 (or 9/5 if you prefer) but a heckuva lot
> easier. I
> never did learn my "1.8 times" tables...
>
> Again, round it if you trip over something like 74 - 7.4.
> The answer is
> 66.6. But does it really matter if you decide to subtract 10 and get
> 64? Or subtract 7 and get 67?
>
> Subtract 30 then 2 rather than 32. Why? Because it is easier to not
> deal with the 1's digit until you have to. If you feel you have to.
>
> I find that I can usually work it out in my head in under a
> second and
> get within a few degrees of the "correct" result. Near
> enough for most
> needs. If I'm tired it might take 2 or even 3 seconds to make the
> conversion, especially if I refuse to round things off (being an
> engineer, I sometimes get anal about numbers, which is a good
> indicator
> I'm tired!).
>
> So, for example, let's take 52C. Is the PA too hot?
>
> The real method:
>
> 2 x 52 = 104.
> 104 - 10.4 = 94 (near enough)
> 94 + 30 = 124
> 124 + 2 = 126(if you really care...)
>
> If you'd rounded it:
>
> 2 x 50 = 100
> 100 - 10 = 90
> 90 + 30 = 120
> 120 + 2 = 122.
>
> Still close enough to decide if your finals are cooking!
> (They aren't).
> Would the 4 degree difference have made you change you mind
> about the
> safety of your PA transistors? I doubt it.
>
> F to C is much slower, but I rarely have to do that :-)
>
> Enjoy!
>
> Lyle KK7P
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com

ON4WIX

Re: K3 - REF CAL Question

Let's see who can answer this question first (without looking at a
thermometer!):

There is one point on the scale of a thermometer where the temp in Celsius
and Farenheit are equal. Which one?

Have fun,

Glenn ON4WIX
----- Original Message -----
From: "Joe Subich, W4TV" <[hidden email]>
To: "'Lyle Johnson'" <[hidden email]>; <[hidden email]>
Cc: <[hidden email]>; <[hidden email]>
Sent: Wednesday, June 18, 2008 12:58 AM
Subject: RE: [Elecraft] K3 - REF CAL Question

> F to C is much slower,

Not really ... (F - 30)/2 is generally within 10% and
(F - 32) * 1.1 / 2 is within about 1%. Both are easy/quick.

Unfortunately, mental math and estimation are skills that have
been lost with the "calculator generation."

73,

... Joe, W4TV

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--------------------------------------------------------------------------------

No virus found in this incoming message.
Checked by AVG.
Version: 8.0.100 / Virus Database: 270.3.0/1505 - Release Date: 16/06/2008
7:20

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ON4WIX

Re: K3 - REF CAL Question

In reply to this post by Joe Subich, W4TV-3

Let's see who first answers this one right (without looking at a
thermometer!):

There is one point on the scale of a thermometer where the temp in °C equals
the temp in F.
Which one is that?
Feel free to prove mathematically...

Enjoy!
Glenn ON4WIX

----- Original Message -----
From: "Joe Subich, W4TV" <[hidden email]>
To: "'Lyle Johnson'" <[hidden email]>; <[hidden email]>
Cc: <[hidden email]>; <[hidden email]>
Sent: Wednesday, June 18, 2008 12:58 AM
Subject: RE: [Elecraft] K3 - REF CAL Question

> F to C is much slower,

Not really ... (F - 30)/2 is generally within 10% and
(F - 32) * 1.1 / 2 is within about 1%. Both are easy/quick.

Unfortunately, mental math and estimation are skills that have
been lost with the "calculator generation."

73,

... Joe, W4TV

Geoffrey Mackenzie-Kennedy

Re: K3 - REF CAL Question

Minus 40 degrees :-)

73,
Geoff
GM4ESD

----- Original Message -----
From: "ON4WIX" <[hidden email]>
To: <[hidden email]>; "'Lyle Johnson'" <[hidden email]>;
<[hidden email]>
Cc: <[hidden email]>; <[hidden email]>
Sent: Wednesday, June 18, 2008 7:50 AM
Subject: Re: [Elecraft] K3 - REF CAL Question

> Let's see who first answers this one right (without looking at a
> thermometer!):
>
> There is one point on the scale of a thermometer where the temp in °C
> equals the temp in F.
> Which one is that?
> Feel free to prove mathematically...
>
> Enjoy!
> Glenn ON4WIX

Stephen Prior

Re: K3 - REF CAL Question

In reply to this post by ON4WIX

I'll have a go. F is degrees Fahrenheit and C is Celcius:

(F-32) x 5/9 = C, or rearranging,

5F - 160 = 9C

If F = C, we can write

5F - 160 = 9F

-160 = 4F, so F = -40

That's woken me up!

73 Stephen G4SJP

On 18/06/2008 07:50, "ON4WIX" <[hidden email]> wrote:

> Let's see who first answers this one right (without looking at a
> thermometer!):
>
> There is one point on the scale of a thermometer where the temp in °C equals
> the temp in F.
> Which one is that?
> Feel free to prove mathematically...
>
> Enjoy!
> Glenn ON4WIX
>
> ----- Original Message -----
> From: "Joe Subich, W4TV" <[hidden email]>
> To: "'Lyle Johnson'" <[hidden email]>; <[hidden email]>
> Cc: <[hidden email]>; <[hidden email]>
> Sent: Wednesday, June 18, 2008 12:58 AM
> Subject: RE: [Elecraft] K3 - REF CAL Question
>
>
>
>
>> F to C is much slower,
>
> Not really ... (F - 30)/2 is generally within 10% and
> (F - 32) * 1.1 / 2 is within about 1%. Both are easy/quick.
>
> Unfortunately, mental math and estimation are skills that have
> been lost with the "calculator generation."
>
> 73,
>
> ... Joe, W4TV
>
>
>
>
>> -----Original Message-----
>> From: [hidden email]
>> [mailto:[hidden email]] On Behalf Of Lyle Johnson
>> Sent: Tuesday, June 17, 2008 5:14 PM
>> To: [hidden email]
>> Cc: [hidden email]; [hidden email]
>> Subject: Re: [Elecraft] K3 - REF CAL Question
>>
>>
>>> You have to do that with your calculator :-)
>>
>> C to F is fast and easy to do in your head.
>>
>> The "real" formula is:
>>
>> F = (1.8 * C) + 32
>>
>> My mental algorithm is:
>>
>> double the value,
>> subtract 10% (round it off, who cares if it is a degree or two off),
>> add 30,
>> then add 2 (if you feel the need for the extra precision).
>>
>> Most of us can double a number in our head pretty easily.
>> Round it to
>> the nearest 5 and then double it if you have trouble doubling
>> 37 or 43
>> or 51. Hey! It's just the "two times" tables, which we all
>> learned well
>> before our 9th birthday.
>>
>> Doubling and then taking off 10% of the result is the same as
>> multiplying by 1.8 (or 9/5 if you prefer) but a heckuva lot
>> easier. I
>> never did learn my "1.8 times" tables...
>>
>> Again, round it if you trip over something like 74 - 7.4.
>> The answer is
>> 66.6. But does it really matter if you decide to subtract 10 and get
>> 64? Or subtract 7 and get 67?
>>
>> Subtract 30 then 2 rather than 32. Why? Because it is easier to not
>> deal with the 1's digit until you have to. If you feel you have to.
>>
>> I find that I can usually work it out in my head in under a
>> second and
>> get within a few degrees of the "correct" result. Near
>> enough for most
>> needs. If I'm tired it might take 2 or even 3 seconds to make the
>> conversion, especially if I refuse to round things off (being an
>> engineer, I sometimes get anal about numbers, which is a good
>> indicator
>> I'm tired!).
>>
>> So, for example, let's take 52C. Is the PA too hot?
>>
>> The real method:
>>
>> 2 x 52 = 104.
>> 104 - 10.4 = 94 (near enough)
>> 94 + 30 = 124
>> 124 + 2 = 126(if you really care...)
>>
>> If you'd rounded it:
>>
>> 2 x 50 = 100
>> 100 - 10 = 90
>> 90 + 30 = 120
>> 120 + 2 = 122.
>>
>> Still close enough to decide if your finals are cooking!
>> (They aren't).
>> Would the 4 degree difference have made you change you mind
>> about the
>> safety of your PA transistors? I doubt it.
>>
>> F to C is much slower, but I rarely have to do that :-)
>>
>> Enjoy!
>>
>> Lyle KK7P
>>
>> _______________________________________________
>> Elecraft mailing list
>> Post to: [hidden email]
>> You must be a subscriber to post to the list.
>> Subscriber Info (Addr. Change, sub, unsub etc.):
>> http://mailman.qth.net/mailman/listinfo/elecraft
>>
>> Help: http://mailman.qth.net/subscribers.htm
>> Elecraft web page: http://www.elecraft.com
>
> _______________________________________________
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> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
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>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>
>
> ------------------------------------------------------------------------------
> --
>
>
>
> No virus found in this incoming message.
> Checked by AVG.
> Version: 8.0.100 / Virus Database: 270.3.0/1505 - Release Date: 16/06/2008
> 7:20
>
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> Elecraft web page: http://www.elecraft.com
>

Dave Van Wallaghen

RE: K3 - REF CAL Question

In reply to this post by ON4WIX

-40 - and the only reason I know this is that I was working in Ottawa at the
time and asked what -40 was in Fahrenheit ;-) I still can't believe I forgot
to take gloves on that trip. Fortunately, I only had to walk a couple of
blocks from the hotel to the Canadian Patent Office :-)

73,
Dave W8FGU

> -----Original Message-----
> From: [hidden email] [mailto:elecraft-
> [hidden email]] On Behalf Of ON4WIX
> Sent: Wednesday, June 18, 2008 2:50 AM
> To: [hidden email]; 'Lyle Johnson'; [hidden email]
> Cc: [hidden email]; [hidden email]
> Subject: Re: [Elecraft] K3 - REF CAL Question
>
> Let's see who first answers this one right (without looking at a
> thermometer!):
>
> There is one point on the scale of a thermometer where the temp in °C
> equals
> the temp in F.
> Which one is that?
> Feel free to prove mathematically...
>
> Enjoy!
> Glenn ON4WIX
>
> ----- Original Message -----
> From: "Joe Subich, W4TV" <[hidden email]>
> To: "'Lyle Johnson'" <[hidden email]>; <[hidden email]>
> Cc: <[hidden email]>; <[hidden email]>
> Sent: Wednesday, June 18, 2008 12:58 AM
> Subject: RE: [Elecraft] K3 - REF CAL Question
>
>
>
>
> > F to C is much slower,
>
> Not really ... (F - 30)/2 is generally within 10% and
> (F - 32) * 1.1 / 2 is within about 1%. Both are easy/quick.
>
> Unfortunately, mental math and estimation are skills that have
> been lost with the "calculator generation."
>
> 73,
>
> ... Joe, W4TV
>
>
>
>
> > -----Original Message-----
> > From: [hidden email]
> > [mailto:[hidden email]] On Behalf Of Lyle Johnson
> > Sent: Tuesday, June 17, 2008 5:14 PM
> > To: [hidden email]
> > Cc: [hidden email]; [hidden email]
> > Subject: Re: [Elecraft] K3 - REF CAL Question
> >
> >
> > > You have to do that with your calculator :-)
> >
> > C to F is fast and easy to do in your head.
> >
> > The "real" formula is:
> >
> > F = (1.8 * C) + 32
> >
> > My mental algorithm is:
> >
> > double the value,
> > subtract 10% (round it off, who cares if it is a degree or two off),
> > add 30,
> > then add 2 (if you feel the need for the extra precision).
> >
> > Most of us can double a number in our head pretty easily.
> > Round it to
> > the nearest 5 and then double it if you have trouble doubling
> > 37 or 43
> > or 51. Hey! It's just the "two times" tables, which we all
> > learned well
> > before our 9th birthday.
> >
> > Doubling and then taking off 10% of the result is the same as
> > multiplying by 1.8 (or 9/5 if you prefer) but a heckuva lot
> > easier. I
> > never did learn my "1.8 times" tables...
> >
> > Again, round it if you trip over something like 74 - 7.4.
> > The answer is
> > 66.6. But does it really matter if you decide to subtract 10 and get
> > 64? Or subtract 7 and get 67?
> >
> > Subtract 30 then 2 rather than 32. Why? Because it is easier to not
> > deal with the 1's digit until you have to. If you feel you have to.
> >
> > I find that I can usually work it out in my head in under a
> > second and
> > get within a few degrees of the "correct" result. Near
> > enough for most
> > needs. If I'm tired it might take 2 or even 3 seconds to make the
> > conversion, especially if I refuse to round things off (being an
> > engineer, I sometimes get anal about numbers, which is a good
> > indicator
> > I'm tired!).
> >
> > So, for example, let's take 52C. Is the PA too hot?
> >
> > The real method:
> >
> > 2 x 52 = 104.
> > 104 - 10.4 = 94 (near enough)
> > 94 + 30 = 124
> > 124 + 2 = 126(if you really care...)
> >
> > If you'd rounded it:
> >
> > 2 x 50 = 100
> > 100 - 10 = 90
> > 90 + 30 = 120
> > 120 + 2 = 122.
> >
> > Still close enough to decide if your finals are cooking!
> > (They aren't).
> > Would the 4 degree difference have made you change you mind
> > about the
> > safety of your PA transistors? I doubt it.
> >
> > F to C is much slower, but I rarely have to do that :-)
> >
> > Enjoy!
> >
> > Lyle KK7P
> >
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