Archive for the ‘Amateur Radio’ Category

What is a Code Practice Oscillator

Friday, February 19th, 2016

A code practice oscillator or “CPO” is a simple tone generator that is turned on and off with a telegraph key. The telegraph key can be any straight key, or hand key, or semi-automatic key (bug).

A CPO cannot be used by a paddle, which is designed to operate an “electronic keyer,” not a CPO. An electronic keyer generates one or more dots when the left paddle is pressed and one or more dashes when the right paddle is pressed. If you do connect a paddle to a CPO, both left and right levers will act as straight keys. This is something you want to do only if you are using a single-lever paddle as a cootie key.

Sometimes you can connect the output of an electronic keyer to a CPO but be sure to check that the polarity, voltage, and current of the key line on your CPO are within the limits of your electronic keyer output.

Not all CPOs are created equal. The least expensive and easiest to build use a simple LM555 IC as an oscillator, and the resulting square-wave output can sound a bit harsh. Also there may be “key clicks” or other spurious emissions which can cause problems with (for example0 a repeater’s control circuitry. A sine-wave oscillator sounds much better and haS no bad effects on other equipment, but a sine wave is not actually the best for listening. A shaped side-tone oscillator will have a slightly more “mellow” tone than a sine wave, and is more pleasant to listen to.

What is the Minimum power ouptut from an OHR 100A?

Friday, May 30th, 2014

Just curious what the MINIMUM output of a 40 meter OHR-100A is with the pot turned all the way down. I can’t find that info anywhere online. I realize it may vary from radio to radio. Would you expect
it to key properly at minimum power?

The minimum power is 0.00W and it does not depend on the band. On all OHR 100A transceivers, the
power output is continuously variable from zero to full power. The power control is actually the bias on the driver, so the transmitter will key properly regardless of output power setting. The power output control is a 100 ohm trim pot accessible from the rear of the radio. Full power is at minimum resistance on the emitter of the driver transistor.

Is a single lever paddle a “sideswiper”?

Saturday, April 17th, 2010

Can a single lever paddle be used as a sideswiper or cootie key?  And if so, how would you wire it? (more…)

Can I check continuity with my VOM?

Friday, April 16th, 2010

My digital multimeter has a continuity test, but my new analog VOM does not. Can I check continuity with my VOM, and if so, how?

If you could only have ONE key…

Tuesday, August 25th, 2009

Which one would you choose?

Whoa, what a question!  I mean, what is the REASON that I can have
only one?  Is it because all the key makers have gone out of business, so I get to buy one, at any cost and then never any more?  Or is it because I’m moving into an apartment and only have room on the desk for one key?  Or is it because I can only afford a few dollars for one key? And do I get to keep my paddles and bugs? [g]

What were the Morse requirements?

Wednesday, June 17th, 2009

What were Morse code requirements in Amateur Radio, before the 2001 changes and the complete abolition of code testing in 2005?  And what were the testing procedures? (more…)

What is “Straight Key Night?”

Thursday, November 30th, 2006

Straight Key Night is a 24-hour event during which hams all over North America get on the air using straight keys (i.e., manual telegraph keys). Straight Key Night begins at 0001 on January 1st each year, and goes to 2359Z. Depending on what time zone you are in, Straight Key Night begins in the afternoon or evening of New Year’s Eve for most of us.

Straight Key Night is sponsored by the ARRL. Participants are encouraged to send in logs and comments on their activity, and their nomination for the “best fist” they heard or worked. The ARRL’s announcement for SKN  is printed in “QST” or can be read on their web site.

SKN is not a contest as such, and participants are encouraged to slow down, chat a bit, and enjoy the ambiance which is reminiscent of the radio spectrum in the earliest days of radio telegraphy. You are forging a metaphysical bond with generations of manual telegraphers going back to the 1840s.

What is a “callsign?”

Sunday, January 8th, 2006

Many of our visitors and customers are Amateur Radio Operators. A callsign or “call” is issued by a government to the holder of a radio station license. All radio stations have callsigns, even broadcast radio and TV stations like WNBC. In the case of Amateur Radio licenses, the callsign is associated with a specific individual person, and has become a convenient way for “hams” to identify themselves to each other.