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Don't have a 50W dummy load

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gm3sek

Re: Don't have a 50W dummy load

>
>For how long does the K3 transmit at 50W in the calibration procedure?
>If it's just a few seconds, will a 10W dummy load handle it?
>Barry W2UP
>

Probably not, because it transmits at 50W for several seconds on every
band (even those you had 'disabled' from the normal rotation). My load
is 50W metal film 'glowbar' resistor and that gets quite hot.

73 from Ian GM3SEK

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Warren Merkel

Re: Don't have a 50W dummy load

In reply to this post by Brian Murrey

That kit from OHR looks nicely done. I wonder if the pcb was immersed in a gallon can of mineral oil instead of the included case, how much more power could it withstand then? 5x-10x maybe? I could use the enclosure for something else. Otherwise I'd get a full paint can kit off ebay for about the same $.

Warren KD4Z

On March 24, 2015 5:39:04 PM EDT, Brian <[hidden email]> wrote:

>Excellent advice Don. I bought a 100w dummy load kit from OHR. It's
>called the RFL-100 and it's about $40, comes in a very nice cabinet,
>and
>takes less than an hour to build. It has come in handy more times than
>
>I can count.
>
>http://www.ohr.com/rfl100.htm
>
>Oak Hills has some good goods.
>
>73 de KB9BVN
>Brian Murrey

wayne burdick

Re: Don't have a 50W dummy load

Administrator

In reply to this post by Barry

If you do the TX GAIN procedure manually as described in the owner's manual, you can definitely use a 10-W dummy load. Just allow several seconds of cooling after aligning each band.

73,
Wayne
N6KR

On Mar 25, 2015, at 5:55 AM, Barry <[hidden email]> wrote:

> For how long does the K3 transmit at 50W in the calibration procedure?
> If it's just a few seconds, will a 10W dummy load handle it?
> Barry W2UP
>
>
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/Don-t-have-a-50W-dummy-load-tp7600633p7600664.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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Elecraft mailing list

Fw: Don't have a 50W dummy load

In reply to this post by Warren Merkel

HOW ABOUT A LAMP WITH 100 WATT BLUB, THATS ALL US OLD GUYS HAD! 73s Bob W5RG

----- Forwarded Message -----
From: Warren Merkel <[hidden email]>
To: [hidden email]
Sent: Wednesday, March 25, 2015 1:17 PM
Subject: Re: [Elecraft] Don't have a 50W dummy load

That kit from OHR looks nicely done. I wonder if the pcb was immersed in a gallon can of mineral oil instead of the included case, how much more power could it withstand then? 5x-10x maybe? I could use the enclosure for something else. Otherwise I'd get a full paint can kit off ebay for about the same $.

Warren KD4Z

On March 24, 2015 5:39:04 PM EDT, Brian <[hidden email]> wrote:

--
Sent from my Android device with K-9 Mail. Please excuse my brevity.

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Mike Reublin NF4L

Re: Fw: Don't have a 50W dummy load

That will cause the owl to blink, thus losing orientation to True North.

Mike NF4L

> On Mar 25, 2015, at 14:25, Bob Gibson via Elecraft <[hidden email]> wrote:
>
> HOW ABOUT A LAMP WITH 100 WATT BLUB, THATS ALL US OLD GUYS HAD! 73s Bob W5RG
>
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vk2rq

Re: Fw: Don't have a 50W dummy load

In reply to this post by Elecraft mailing list

For the calibration procedure, you need the load to be a known 50 ohm resistive impedance. Using a 100W light bulb will not provide the required impedance, and will produce inaccurate results and possible damage the transceiver.

73, Matt VK2RQ

> On 26 Mar 2015, at 5:25 am, Bob Gibson via Elecraft <[hidden email]> wrote:
>
> HOW ABOUT A LAMP WITH 100 WATT BLUB, THATS ALL US OLD GUYS HAD! 73s Bob W5RG
>
> ----- Forwarded Message -----
> From: Warren Merkel <[hidden email]>
> To: [hidden email]
> Sent: Wednesday, March 25, 2015 1:17 PM
> Subject: Re: [Elecraft] Don't have a 50W dummy load
>
> That kit from OHR looks nicely done. I wonder if the pcb was immersed in a gallon can of mineral oil instead of the included case, how much more power could it withstand then? 5x-10x maybe? I could use the enclosure for something else. Otherwise I'd get a full paint can kit off ebay for about the same $.
>
> Warren KD4Z
>
>> On March 24, 2015 5:39:04 PM EDT, Brian <[hidden email]> wrote:
>> Excellent advice Don. I bought a 100w dummy load kit from OHR. It's
>> called the RFL-100 and it's about $40, comes in a very nice cabinet,
>> and
>> takes less than an hour to build. It has come in handy more times than
>>
>> I can count.
>>
>> http://www.ohr.com/rfl100.htm
>>
>> Oak Hills has some good goods.
>>
>> 73 de KB9BVN
>> Brian Murrey
>
>
> --
> Sent from my Android device with K-9 Mail. Please excuse my brevity.
>
>
> ______________________________________________________________
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Cliff Frescura

Re: Fw: Don't have a 50W dummy load

" Using a 100W light bulb will not provide the required impedance, and will
produce inaccurate results and possible damage the transceiver."

True, also - In the "old days" there was no need to specify *incandescent*
light bulb. Wonder what would happen with a CFL or LED lamp (do not try
this)?

The key word is Resistive.

73,

Cliff K3LL

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Matt
VK2RQ
Sent: Wednesday, March 25, 2015 11:52 AM
To: Bob Gibson
Cc: Elecraft Reflector
Subject: Re: [Elecraft] Fw: Don't have a 50W dummy load

For the calibration procedure, you need the load to be a known 50 ohm
resistive impedance. Using a 100W light bulb will not provide the required
impedance, and will produce inaccurate results and possible damage the
transceiver.

73, Matt VK2RQ

> On 26 Mar 2015, at 5:25 am, Bob Gibson via Elecraft
<[hidden email]> wrote:
>
> HOW ABOUT A LAMP WITH 100 WATT BLUB, THATS ALL US OLD GUYS HAD! 73s Bob
W5RG
>
> ----- Forwarded Message -----
> From: Warren Merkel <[hidden email]>
> To: [hidden email]
> Sent: Wednesday, March 25, 2015 1:17 PM
> Subject: Re: [Elecraft] Don't have a 50W dummy load
>
> That kit from OHR looks nicely done. I wonder if the pcb was immersed in
a gallon can of mineral oil instead of the included case, how much more
power could it withstand then? 5x-10x maybe? I could use the enclosure for
something else. Otherwise I'd get a full paint can kit off ebay for about
the same $.

>
> Warren KD4Z
>
>> On March 24, 2015 5:39:04 PM EDT, Brian <[hidden email]> wrote:
>> Excellent advice Don. I bought a 100w dummy load kit from OHR. It's
>> called the RFL-100 and it's about $40, comes in a very nice cabinet,
>> and takes less than an hour to build. It has come in handy more
>> times than
>>
>> I can count.
>>
>> http://www.ohr.com/rfl100.htm
>>
>> Oak Hills has some good goods.
>>
>> 73 de KB9BVN
>> Brian Murrey
>
>
> --
> Sent from my Android device with K-9 Mail. Please excuse my brevity.
>
>
> ______________________________________________________________
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>
>
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Tony Estep

Re: Don't have a 50W dummy load

In reply to this post by wayne burdick

On Wed, Mar 25, 2015 at 1:20 PM, Wayne Burdick <[hidden email]> wrote:

> ...you can definitely use a 10-W dummy load....

==============
Yep, you can. Worked perfectly. Thanks to Wayne and again thanks to the
others who actually understood my question and provided answers.

Tony KT0NY
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EricJ-2

Re: Fw: Don't have a 50W dummy load

In reply to this post by vk2rq

Us old guys had tough tube transmitters with widely tunable output
networks that made the rigs more tolerant to our general abuse of known
electronic theory.

Eric
KE6US

On 26 Mar 2015, at 5:25 am, Bob Gibson via Elecraft
<[hidden email]> wrote:

HOW ABOUT A LAMP WITH 100 WATT BLUB, THATS ALL US OLD GUYS HAD! 73s Bob
W5RG
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Bill Turner-2

Re: Fw: Don't have a 50W dummy load

In reply to this post by Cliff Frescura

------------ ORIGINAL MESSAGE ------------(may be snipped)

On Wed, 25 Mar 2015 12:05:18 -0700, you wrote:

>The key word is Resistive.

REPLY:

I have used light bulbs in the olden days, although not for the K3 cal
procedure. The trick is to insert a variable cap in series to tune out
the reactance. Works well, but has to be retuned for each band of
course, and the resistance varies with brightness. Because of the
variation, do not use with an automatic antenna tuner or the tuner
will constantly seek a correct tune.

A real dummy load is better.

73, Bill W6WRT
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Don Wilhelm-4

Re: Fw: Don't have a 50W dummy load

In reply to this post by Elecraft mailing list

I suspect the TX Gain Calibration would fail due to "High SWR".
Yes, TX CAL will do that. You need a good 50 ohm non-reactive dummy
load good to 54MHz.

Light bulbs worked well with old transmitters that had an output circuit
that could match most anything. We did not need tuners back then - but
then along came limited range transmitter output circuits which
sometimes needed a tuner, but today's transmitters need to see a 50 ohm
non-reactive load if they are to work properly - and then tuners became
essential - they just moved the matching network out of the transmitter
and put the equivalent into another box called an antenna tuner.

73,
Don W3FPR

On 3/25/2015 2:25 PM, Bob Gibson via Elecraft wrote:
> HOW ABOUT A LAMP WITH 100 WATT BLUB, THATS ALL US OLD GUYS HAD! 73s Bob W5RG
>
>

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k6dgw

Re: Fw: Don't have a 50W dummy load

In reply to this post by Mike Reublin NF4L

Ummm ... several reasons. Resistance component of an incandescent bulb
impedance varies with the temperature [brightness] of the filament.
They are also somewhat reactive. Push-pull vacuum tubes and link
coupling didn't care about SWR, I don't even remember the term in the
ham lexicon until the Pi-network and 50 ohm output was invented.

They're also not very good at the "dummy" part. N6BT, of Force 12 fame,
is fairly famous for his "phased illuminator," 3 300 watt bulbs mounted
on his deck railing in a V arrangement on which he worked all
continents. More than once I made contacts while using a 100 watt bulb
as my dummy load.

If you're going to use the paralleled metal film resistor construction
method, be sure to keep the resistor leads short and spaced them from
each other. Lead inductance will start to become a factor on 6 m and
up. I built mine with 40 2K 2W resistors and it works find at 100W if
used intermittently. It's air cooled. Don't know how much putting it
in oil would improve the dissipation.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015
- www.cqp.org

>> On Mar 25, 2015, at 14:25, Bob Gibson via Elecraft <[hidden email]> wrote:
>>
>> HOW ABOUT A LAMP WITH 100 WATT BLUB, THATS ALL US OLD GUYS HAD! 73s Bob W5RG

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Elecraft mailing list

Fw: Fw: Don't have a 50W dummy load

You guys are right!! SORRY FOR MY STUPID POST!! Sixty years ago I did not have money for a dummy load..ENJOY 73s Bob W5RG

----- Forwarded Message -----
From: Fred Jensen <[hidden email]>
To: [hidden email]
Sent: Wednesday, March 25, 2015 6:41 PM
Subject: Re: [Elecraft] Fw: Don't have a 50W dummy load

Ummm ... several reasons. Resistance component of an incandescent bulb
impedance varies with the temperature [brightness] of the filament.
They are also somewhat reactive. Push-pull vacuum tubes and link
coupling didn't care about SWR, I don't even remember the term in the
ham lexicon until the Pi-network and 50 ohm output was invented.

They're also not very good at the "dummy" part. N6BT, of Force 12 fame,
is fairly famous for his "phased illuminator," 3 300 watt bulbs mounted
on his deck railing in a V arrangement on which he worked all
continents. More than once I made contacts while using a 100 watt bulb
as my dummy load.

If you're going to use the paralleled metal film resistor construction
method, be sure to keep the resistor leads short and spaced them from
each other. Lead inductance will start to become a factor on 6 m and
up. I built mine with 40 2K 2W resistors and it works find at 100W if
used intermittently. It's air cooled. Don't know how much putting it
in oil would improve the dissipation.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015
- www.cqp.org

>> On Mar 25, 2015, at 14:25, Bob Gibson via Elecraft <[hidden email]> wrote:
>>
>> HOW ABOUT A LAMP WITH 100 WATT BLUB, THATS ALL US OLD GUYS HAD! 73s Bob W5RG

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riese-k3djc

Re: Fw: Fw: Don't have a 50W dummy load

Oh Shucks

at some point elmers all used a lamp for a dummy load
back in the day with Pi tuning you could transfer a lot of
your output to a lamp,,, on 6 meters , as I recall ,, parts of the
filament would be brighter than other parts
we could talk about RF burns

HAR

Bob K3DJC

On Thu, 26 Mar 2015 00:51:58 +0000 (UTC) Bob Gibson via Elecraft
<[hidden email]> writes:

> You guys are right!! SORRY FOR MY STUPID POST!! Sixty years ago I
> did not have money for a dummy load..ENJOY 73s Bob W5RG
>
>
> Subject: Re: [Elecraft] Fw: Don't have a 50W dummy load
>
> Ummm ... several reasons. Resistance component of an incandescent
> bulb
> impedance varies with the temperature [brightness] of the filament.
> They are also somewhat reactive.

Tony Estep

Re: Fw: Fw: Don't have a 50W dummy load

On Wed, Mar 25, 2015 at 8:11 PM, <[hidden email]> wrote:

> ...at some point elmers all used a lamp for a dummy load
> back in the day with Pi tuning...

-------------
Yep, back in 1958 I loaded up my first home-brew transmitter (6146, of
course) with a 100W bulb and I am one of the many hams who can claim to
have made a qso using the bulb for an antenna, on 40M cw. The output
capacitor of my pi-net was one of those double-gang 365 uuf per gang
broadcast receiver jobbies.

Tony KT0NY
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Charlie T, K3ICH

Re: Fw: Don't have a 50W dummy load

In reply to this post by k6dgw

Yes, but the inductances are all in parallel. I built a decent dummy load
out of 24, 1200 Ohm, 10 watt wire wound resistors all in parallel between
two squares of fiberglass PC board. The SWR was only about 1.2:1 on 15
Meters and about 1.5:1 on 10 meters. Admittedly, not a perfect load, but
certainly adequate for the low bands just to soak up some RF.

73, Charlie k3ICH

>
> If you're going to use the paralleled metal film resistor construction
> method, be sure to keep the resistor leads short and spaced them from each
> other. Lead inductance will start to become a factor on 6 m and up. I
> built mine with 40 2K 2W resistors and it works find at 100W if used
> intermittently. It's air cooled. Don't know how much putting it in oil
> would improve the dissipation.

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Edward R Cole

Re: Fw: Don't have a 50W dummy load

In reply to this post by Mike Reublin NF4L

Just stop all this and go buy one
Lots of them listed under "Ham Radio Dummy Load" on e-bay at about a
buck a watt.

I bought a NARDA 40w load with N-connector good to 12.6 GHz for $40
(from a friend on-line).
Yeah I had a 100w light bulb and a Heath Cantenna way back

Now mine mostly made by Bird, NARDA, M/A, Midwest MW, etc. My 500w
is made by Sierra and I paid maybe $50 at a flea market (it has
built-in power meter). SWR is not quite 1:1.00 (1.4 as I recall) - so what.

73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
[hidden email]

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'DGB'

Re: Fw: Don't have a 50W dummy load

Checked my Cantenna today, 78 ohms.

Took it apart, even measured the raw resistor.

Ordered a replacement from Alan W1GA as someone else mentioned.

eBay # 221724743523 for description and options

Easy disassembly and price war right ... $24.50 shipped.

Thanks for all the info on DL's.

73 Dwight NS9I

On 3/26/2015 12:17 PM, Edward R Cole wrote:

> Just stop all this and go buy one
> Lots of them listed under "Ham Radio Dummy Load" on e-bay at about a
> buck a watt.
>
> I bought a NARDA 40w load with N-connector good to 12.6 GHz for $40
> (from a friend on-line).
> Yeah I had a 100w light bulb and a Heath Cantenna way back
>
> Now mine mostly made by Bird, NARDA, M/A, Midwest MW, etc. My 500w is
> made by Sierra and I paid maybe $50 at a flea market (it has built-in
> power meter). SWR is not quite 1:1.00 (1.4 as I recall) - so what.
>
> 73, Ed - KL7UW
> http://www.kl7uw.com
> "Kits made by KL7UW"
> Dubus Mag business:
> [hidden email]
>
> ______________________________________________________________
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>
>

k6dgw

Re: Fw: Don't have a 50W dummy load

In reply to this post by Charlie T, K3ICH

Mine works fine at 220, VSWR on 440 is about 1.3:1 and rising fast. On
the QRP one I made, I left about 1" leads on the resistors, I had a
small brass tube to connect the center conductor down to the bottom
plate and I didn't want to cut it. VSWR on 6 meters is 1.6:1.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015
- www.cqp.org

On 3/25/2015 8:13 PM, Charlie T, K3ICH wrote:

> Yes, but the inductances are all in parallel. I built a decent dummy
> load out of 24, 1200 Ohm, 10 watt wire wound resistors all in parallel
> between two squares of fiberglass PC board. The SWR was only about
> 1.2:1 on 15 Meters and about 1.5:1 on 10 meters. Admittedly, not a
> perfect load, but certainly adequate for the low bands just to soak up
> some RF.
>
> 73, Charlie k3ICH
>>
>> If you're going to use the paralleled metal film resistor construction
>> method, be sure to keep the resistor leads short and spaced them from
>> each other. Lead inductance will start to become a factor on 6 m and
>> up. I built mine with 40 2K 2W resistors and it works find at 100W if
>> used intermittently. It's air cooled. Don't know how much putting it
>> in oil would improve the dissipation.

W1KSZ

Re: Fw: Don't have a 50W dummy load

You can often find Dummy loads at your local Ham Flea. I found two 50
Watt Birds
for $10 each at the last one.

73, Dick, W1KSZ

On 3/26/2015 11:15 AM, Fred Jensen wrote:

> Mine works fine at 220, VSWR on 440 is about 1.3:1 and rising fast.
> On the QRP one I made, I left about 1" leads on the resistors, I had a
> small brass tube to connect the center conductor down to the bottom
> plate and I didn't want to cut it. VSWR on 6 meters is 1.6:1.
>
> 73,
>
> Fred K6DGW
> - Northern California Contest Club
> - CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015
> - www.cqp.org
>
> On 3/25/2015 8:13 PM, Charlie T, K3ICH wrote:
>> Yes, but the inductances are all in parallel. I built a decent dummy
>> load out of 24, 1200 Ohm, 10 watt wire wound resistors all in parallel
>> between two squares of fiberglass PC board. The SWR was only about
>> 1.2:1 on 15 Meters and about 1.5:1 on 10 meters. Admittedly, not a
>> perfect load, but certainly adequate for the low bands just to soak up
>> some RF.
>>
>> 73, Charlie k3ICH
>>>
>>> If you're going to use the paralleled metal film resistor construction
>>> method, be sure to keep the resistor leads short and spaced them from
>>> each other. Lead inductance will start to become a factor on 6 m and
>>> up. I built mine with 40 2K 2W resistors and it works find at 100W if
>>> used intermittently. It's air cooled. Don't know how much putting it
>>> in oil would improve the dissipation.
>
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