Date
1 - 13 of 13
Dummy?
|
Michael McEwen
I guess I'm the dummy asking this, but I haven't found a simple solution thru Google, so I thought I would ask the experts directly: what is the simplest dummy load I can make for my QRP rigs? TNX in advance...-- 73, Doc K5OSA - QTH: EM04sr ARRL - LFSARC - 4sqrp #801 - NAQCC #7625 Michael T McEwen Lt Col, US Army, Ret PO Box 338 Medicine Park, OK 73557-0338 H: 580 529-3412 C: 580 919-9205
|
|||||||||||||||||||||
|
|
|||||||||||||||||||||
|
Robert 'RC' Conley <rc.kc5wa@...>
a 51 ohm soldered in to a connector (pl259 or BNC)
On Mon, Feb 2, 2015 at 10:10 AM, Michael McEwen mcewenk5osa@... [4sqrp] <4sqrp@...> wrote:
--
Confirmed Countries 222
|
|||||||||||||||||||||
|
|
|||||||||||||||||||||
|
davemrtn
A number 47 incandescent indicator
light bulb. I used to connect one of these to a PL-259 and use on
CB radios as a dummy load.
On 02/02/2015 10:10 AM, Michael McEwen mcewenk5osa@...
[4sqrp] wrote:
-- David Martin - K5DCM ---o0o--- Mountain Home, Arkansas Guns don't kill people, any more than spoons & forks cause obesity. Definition: Voter Apathy - When a jerk wearing a robe can overturn the vote of the people, what's the point of voting ?
|
|||||||||||||||||||||
|
|
|||||||||||||||||||||
|
Martin Huyett <huyettmeh@...>
I suggest soldering two 100 ohm 1 watt resistors, or four 200 ohm1/2 watt resistors in parallel to a connector. That will give you 2 watts of dissipation which will be adequate for 5 watts power for a few seconds or minutes. If you need more power simply use two 100 ohm 2 watt or four 200 ohm 1 watt resisters to get four or so watts of power. Keep the leads reasonably short and it will work well on almost any frequency.
Of course if you have a 2 to 5 watt 47 or 50 ohm resistor just use it! Also be sure the resistors are carbon and NOT wire wound as the wire would ones will have some inductance which may mess up things on certain frequencies.
Martin
From: 4sqrp@... [mailto:4sqrp@...]
Sent: Monday, February 02, 2015 10:11 AM To: 4sqrp@... Subject: [4sqrp] Dummy?
I guess I'm the dummy asking this, but I haven't found a simple solution thru Google, so I thought I would ask the experts directly: what is the simplest dummy load I can make for my QRP rigs? TNX in advance...
73,
|
|||||||||||||||||||||
|
|
|||||||||||||||||||||
|
Wayne Dillon
Hi Doc, Any 50 Ohm NON INDUCTIVE resistor that will handle the wattage. Smaller carbon film resistors in parallel will work, for instance, a couple of 100 ohm 1 watt resistors in parallel will show 50 ohms and the wattage dissipation is 2 watts. Does this help? 72/3 es God Bless de Wayne - KC0PMH
On Mon, Feb 2, 2015 at 10:10 AM, Michael McEwen mcewenk5osa@... [4sqrp] <4sqrp@...> wrote:
--
http://www.qsl.net/kc0pmh/ Under construction but please visit anyway.
QRP - EFFICIENCY AND SKILL, NOT POWER.
I'm British by birth but American by CHOICE! Jesus came to pay a debt He didn't owe because we owe a debt we cannot pay... The Lord bless you and keep you The Lord make His face shine upon you, and be gracious unto you The Lord lift up his contenance upon you and give you peace. God Bless from Wayne Dillon - KC0PMH Joshua 24:14-15 2 Cor 5:17 1 Jn 2:17 4SQRP #95 FPQRP #342 (Flying Pigs QRP Club)
NAQCC # 0759 QRP-ARCI #11505 SKCC #1155T CW Ragchewers Anonymous #40
SOC #848 30MDG#1176 NEQRP #693 GORC #192 DMC (Digital Modes Club) # 06686
|
|||||||||||||||||||||
|
|
|||||||||||||||||||||
|
John Lonigro
Doc:
toggle quoted messageShow quoted text
If you are talking about a 5 Watt maximum dummy load, one thing you could do is buy eight 100 ohm, 1 Watt carbon composition (not wirewound) resistors. Put four of them in parallel to get 25 ohms. Do the same with the other four. Then put one group of four in series with the other group of four and you have a 50 ohm, 8 Watt dummy load. If you arrange them properly, you'll have both ends close to each other and you can attach them to whatever connector you need, BNC, PL-259, RCA plug, etc. A small piece of coax between the resistors and connector will make it easier to attach everything. If you only have 1/2 Watt resistors, you could do the same thing, but crank down your power a little. Also, Elecraft and QRPKITS.COM and probably others sell QRP dummy load kits for not too much money. They use pretty much the same principal. 72, John, AA0VE
On 02/02/2015 10:10 AM, Michael McEwen
mcewenk5osa@... [4sqrp] wrote:
|
|||||||||||||||||||||
|
|
|||||||||||||||||||||
|
Tom Sevart
I made one with 8 1/2 watt 100 Ohm resistors (2 in series 4X in parallel) connected to an SO-239 jack. Here's a copy of my old webpage on it: http://www.geocities.ws/n2uhc/dummy_load.html.
On Mon, Feb 2, 2015 at 10:10 AM, Michael McEwen mcewenk5osa@... [4sqrp] <4sqrp@...> wrote:
--
Tom Sevart N2UHC St. Paul, KS
|
|||||||||||||||||||||
|
|
|||||||||||||||||||||
|
Bill Cromwell
Hi Michael,
toggle quoted messageShow quoted text
We all need a dummy load (or several) and it's always good to know how to make your own. If you don't know how then you be a dummy for NOT asking. Good luck with your project. 73, Bill KU8H Proud Owner of the Forty Meter Band
On 02/02/2015 11:10 AM, Michael McEwen mcewenk5osa@gmail.com [4sqrp] wrote:
I guess I'm the dummy asking this, but I haven't found a simple solution thru Google, so I thought I would ask the experts directly: what is the simplest dummy load I can make for my QRP rigs?
|
|||||||||||||||||||||
|
|
|||||||||||||||||||||
|
Don Wilhelm <w3fpr@...>
Doc,
toggle quoted messageShow quoted text
If you want an accurate 50 ohm dummy load, take a look at the Caddock 50 ohm 1% Thick Film Resistors. They are available in power ratings from 15 watts to 100 watts. They *must* be mounted on a heatsink to achieve the rated power level (salvage a heatsink from a defunct computer). Mount the connector with zero length leads and you have a dummy load that is flat up to 500 MHz and accurate enough for instrumentation. Take a look at http://www.mmccs.com/mmarc/n0ss/dl_30w_hf-uhf.pdf for one implementation. You can find another QRP dummy load at http://www.mmccs.com/mmarc/n0ss/qrp_dummyload_w1cg.pdf 73, Don W3FPR
On 2/2/2015 11:10 AM, Michael McEwen
mcewenk5osa@... [4sqrp] wrote:
|
|||||||||||||||||||||
|
|
|||||||||||||||||||||
|
moshecontra
I built one with 18 100-ohm half-watt resistors, but with only HF in mind. I also included a crude way to measure the power. Description and pictures here: QRP dummy load - N1OVN
|
|||||||||||||||||||||
|
|
|||||||||||||||||||||
|
Forrest Plumstead
http://www.danssmallpartsandkits.net/ QRP DUMMY LOAD..RF SENSOR KIT.
The artical was by Bill Hickox K5BDZ. This dummy load will handel up to 20 watts
Price on this kit is... $15.00.. includes a copy of the artical.. Ctrl + f dummy load. 73 WB5HQO Forrest Ham Radio WB5HQO Webmaster for BUSH RIVER QUAKER CEMETERY
SKCC Member # 6855 QRPadillo # 59 4SQRP # 857
On Tue, Feb 3, 2015 at 11:52 AM, mbraner@... [4sqrp] <4sqrp@...> wrote:
|
|||||||||||||||||||||
|
|
|||||||||||||||||||||
|
Sam Neal
Hello,
toggle quoted messageShow quoted text
Take a 50 Ohm resistor ( carbon! ) ( 5 Watt if you can find it ) and slide one end with it's wire into a coax connector, so that the resistor is now hidden inside the coax connector. Solder the resistor's wire sticking out of the center pin and cut off the excess. Then, solder the wire on the other end of the now hidden resistor to the coax connector frame and cut off the excess wire. You now have an almost free 50 Ohm dummy load. If you can find one, glue the protective cap that comes on the end of a spool of coax over the open end of the connector for neatness. The only problem I have with mine is keeping up with where it is. 73, Sam Neal N5AF ________________________________________________________
------ Original Message ------
Received: Mon, 02 Feb 2015 10:10:59 AM CST From: "Michael McEwen mcewenk5osa@gmail.com [4sqrp]" <4sqrp@yahoogroups.com> To: "4sqrp@yahoogroups.com" <4sqrp@yahoogroups.com> Subject: [4sqrp] Dummy? I guess I'm the dummy asking this, but I haven't found a simple solution thru Google, so I thought I would ask the experts directly: what is the simplest dummy load I can make for my QRP rigs? TNX in advance... -- 73, Doc K5OSA - QTH: EM04sr ARRL - LFSARC - 4sqrp #801 - NAQCC #7625 Michael T McEwen Lt Col, US Army, Ret PO Box 338 Medicine Park, OK 73557-0338 H: 580 529-3412 C: 580 919-9205
|
|||||||||||||||||||||
|
|
|||||||||||||||||||||
|
Bill Cromwell
Hi Sam,
toggle quoted messageShow quoted text
Better yet - at the back of the shell solder a metal disc (copper is a good bet), over the opening with a small, centered hole for the grounded end of the resistor and solder the resistor lead there. That maintains the impedance straight through the connector/dummy load. This is less important and perhaps completely unimportant at HF, especially from 40 or 30 meters on down through 600 meters and longer. At VHF it becomes very important. Carbon resistors have been shown unreliable/unstable of over the years. Apparently the metal film resistors are superior in *every* way including non-inductive. If you have the carbon resistor and it is still 50 ohms (or 49 ohms etc) by all means use it. Measure it before and after each use just to be sure it is still doing what you think it is doing. I check such things on all of my gear from time to time to avoid unpleasant surprises. BNC size connectors don't have a lot of extra room but it is possible to combine several resistors to increase the power handling ability of the dummy load. I have a couple of BNC shell/dummy loads here that will not handle more than a half watt used to terminate signal generators and receiver tests. The one that is in the PL-259 is good for about ten watts. 73, Bill kU8H
On 02/09/2015 10:48 PM, 'Sam Neal' n5af@usa.net [4sqrp] wrote:
|
|||||||||||||||||||||
|
|
|||||||||||||||||||||
