N1AUP
| Joined: | Sat, Apr 4th 1998, 00:00 | Roles: | N/A | Moderates: | N/A |
Latest Topics
| Topic | Created | Posts | Views | Last Activity |
|---|---|---|---|---|
| NMO 2 / 440 on plastic roof. Ground plane ?? | Apr 8th, 15:26 | 1 | 47 | 1 week, 5 days ago |
| Is it true that high SWR reflections don't fry finals? | Feb 22nd, 06:59 | 5 | 170 | on 22/2/21 |
| WIRES Node getting into my packet station | Feb 1st, 21:42 | 7 | 330 | on 20/2/21 |
| Design for 5/8 wave on 10 meters. | Oct 20th 2020, 11:02 | 2 | 335 | on 20/10/20 |
| Why won't my ARRL designed vertical tune on 20? | Aug 1st 2020, 06:47 | 7 | 522 | on 8/8/20 |
| Vertical antenna using a wire as a radiator. What gauge? | Jul 23rd 2020, 08:17 | 3 | 497 | on 24/7/20 |
| Interesting Voices Discussion Net - DMR TAC316, Wed 10/2/2019. | Sep 28th 2019, 05:02 | 2 | 1,315 | on 2/10/19 |
| DMR Discussion Net. 5/15/2019. | May 6th 2019, 06:53 | 4 | 2,263 | on 16/9/20 |
| Windom antenna. How to design the choke. | Feb 14th 2019, 15:40 | 2 | 1,680 | on 14/2/19 |
| HDSDR is not working. | Feb 15th 2018, 18:43 | 2 | 4,228 | on 26/2/18 |
Latest Posts
| Topic | Author | Posted On |
|---|---|---|
| NMO 2 / 440 on plastic roof. Ground plane ?? | N1AUP | 1 week, 5 days ago |
| I plan to mount a 2 / 440 FM radio in a backhoe that I just bought. A plastic roof sits on top of a steel ROPS cage that forms the sides and top of the cab. If I mount a 5/8 wave antenna on top, it's going to need a ground plane. 1. Is the ROPS cage enough of a ground plane for the antenna if the 3 inch square steel bars makes a rectangle about 2 x 3 feet with the antenna on the plastic in the middle? 2. How close does the ground plane have to be? Could I mount the NMO on an L shaped bracket, and assume that the backhoe arm and frame of the tractor, four feet below, is enough ground plane? Or should I get a deep NMO, mount it in the center of the plastic roof, and put some sort of a hardware cloth mesh screen under the plastic roof? Finally, do I need hardware cloth, or can I use 4, 19 inch pieces of wire to act as ground radials like with a 5/8 base antenna? Thanks |
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| Is it true that high SWR reflections don't fry finals? | N1AUP | on 22/2/21 |
| I was always taught that SWR mismatches blow up finals because too much RF is reflected back at the transistors. The quote from a ham's web site seems to say that this is not correct. So I'm still not sure. Which is correct? I am reading those two articles. |
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| Is it true that high SWR reflections don't fry finals? | N1AUP | on 22/2/21 |
| Is this true? "So, why do people think they can blow up their rigs or linear amplifiers when there is a high SWR on the antenna? Because that can happen, but it is not due to the reflected power! There is a totally different reason. A high SWR on an antenna probably means that the antenna is not tuned to the frequency that is being used. This, in turn, means that the antenna has some inductive or capacitive reactance that is de-tuning the final amplifier. De-tuned final amplifiers draw far too much current and can burn up. The rig or linear amplifier will have to be re-tuned to avoid creating too much heat. Many linears and nearly all tube amplifiers have some tuning knobs that allow you to "dip the plate current" or adjust the SWR by adjusting something on the front of the device. Transistor rigs usually do not have any tuning adjustments. To avoid the extra heat created when running a de-tuned amplifier, there is a protection circuit that will significantly reduce the output power if the SWR is high. " Thanks |
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| WIRES Node getting into my packet station | N1AUP | on 20/2/21 |
| Thanks. Thinking.... |
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| WIRES Node getting into my packet station | N1AUP | on 10/2/21 |
| Do you have an article reference for the frequency counter / gate switch idea? Thanks |
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