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HT and Light Bulb Load
22 November 2020 | by The light-bulb dummy load has been used with HF transceivers from way back in the old days (and sometimes more recently). Also, the Lightbulb QSO Party promoted the use of light bulbs as antennas.
I wanted to find out if I could do the same thing with a 5W handheld transceiver, so I scavenged a bulb from an old string of Christmas tree lights and hooked it up to my Yaesu FT-60. This video shows what happened next.
After I made the video, I checked the specs on the FT-60 and found that the transmit power settings are: 5.0 W (High) / 2.0 W (Middle) / 0.5 W (Low). In the video, I said the middle setting was one half watt, which is incorrect.
I checked the SWR on the light bulb and found it to be 2.7. I was not worried about damaging the handheld radio because they are designed to work into crummy antennas such as the standard rubber duck.
I hope you enjoyed this fun experiment. Sorry about the amateurish video quality…I just shot it with my iPhone and did some simple editing.
73 Bob K0NR
The post HT and Light Bulb Load appeared first on The KØNR Radio Site.
4 Responses to “HT and Light Bulb Load”
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That was fun Bob, thanks for the demo. Amazing what can work…I heard of an Israeli ham who was using his mother’s laundry iron as a dummy load. Unexpectedly he had a QSO with someone in Cyprus!
TRUE STORY: In the mid 1960 I got my Novice license. I had a BC-348Q for a RX and a home brew TX. I said in passing to my parents that I can run 2 meter voice but I would need something like a HeathKit “2’er” Since my Birthday is 2 days before Christmas and Christmas was in a couple of weeks so I got a major surprise, my first commercial radio kit and 2 meters also. Well I built it and for tuning up a #47 bulb was used. Peak for max brightness… Now the funny part of this #47 bulb as a dummy load.
There was another Harry who was a ham and older then me who also had a 2er. I never meet him, but each week-end I and many in the Phoenix/Scottdale area would listen for him. He was doing SOTA, before SOTA became popular. Well one Saturday he was on a peak and for whatever reason I guess he decided to “peak” up the massive 5 watt power before hooking his homemade 3 element beam. I and others could hear him but he did not hear us… Then it became apparent that the front trans switch was on. This was before PTT. The radio had a TR front panel switch. For over 30 minutes he was operating open mic. Not into a antenna, but he later told everyone who jumped him that day, it was on a #47 dummy load. He was a good 5 miles from the valley and at about 5,000 ft.
He was very embarrassed and for months he was teased about actually being on the beam or bulb. I don’t believe he could hear us since the RX was not all that great for one thing, and being AM not too effective. Since that day I keep running across people who with a good RX at least 100 watts and out standing manual tuner, tuned a light bulb into a antenna and actually made contacts. I really need to try it one day…
73 Harry K7ZOV… In those days I was KN7ZOV
Being an Ole Timer—-using bulbs to check out RF radiation & strength or even as a dummy load, was the in-thing in the past years. Always used the normal 6.3 volt pilot lamp in an absorbtion type wavemeter circuit, to check if everything was on frequency & how much juice it was giving !
In the 70s I built a 2x4CX250B Linear amp & hung a 200W light bulb on the wall fed with some heavy duty twin flex—the amp was tuned on 10 meters & I thought it was a good dummy load check—–hello testing a few times into the mike & when I went to standby out came a voice from my Drake R4B speaker—what are you testing–you are loud & clear in the States over the short path !!! I was clean bowled–we made a pefect
Being an Ole Timer—-using bulbs to check out RF radiation & strength or even as a dummy load, was the in-thing in the past years. Always used the normal 6.3 volt pilot lamp in an absorbtion type wavemeter circuit, to check if everything was on frequency & how much juice it was giving !
In the 70s I built a 2x4CX250B Linear amp & hung a 200W light bulb on the wall fed with some heavy duty twin flex—the amp was tuned on 10 meters & I thought it was a good dummy load check—–hello testing a few times into the mike & when I went to standby out came a voice from my Drake R4B speaker—what are you testing–you are loud & clear in the States over the short path !!! I was clean bowled–we made a perfect QSO for 3 minutes !