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9 votes
Accepted

From where do repeaters get their power supply?

You are correct that most repeaters that are on buildings or typical towers get their energy from the commercial grid. The repeaters that I own are all commercially powered. Repeaters that are ...
Glenn W9IQ's user avatar
  • 18.6k
9 votes

How to reduce voltage ripple of a linear power supply?

Unless you haven't mentioned all the parts, you have built an unregulated power supply. The output voltage of a transformer varies depending on load, and the other components will just follow that ...
Kevin Reid AG6YO's user avatar
  • 24.6k
8 votes

Calculation of transceiver current draw

Some of both! It's normal for a linear power amplifier for HF to be something like 50% - 60% efficient. So to make 100W, the radio probably needs 170 - 200 W. There are other power draws in the radio,...
hobbs - KC2G's user avatar
  • 12.5k
7 votes

Are there any cons of running shack on battery?

I don't mean to talk you out of the idea, but I suspect the advantages are not nearly so great as you imagine. Cheaper than a dedicated RF-grade power supply (USD30 for 40 Ah car battery) I don't ...
Phil Frost - W8II's user avatar
6 votes
Accepted

Calculation of transceiver current draw

The rest (of the current) is why your transmitter requires heat sinks (and/or airflow for thermal dissipation). Linear amplifiers are usually not anywhere close to 100% efficient. A high SWR might ...
hotpaw2's user avatar
  • 13.4k
6 votes
Accepted

Practical differences between switching and linear power supplies?

The only reason to use a linear power supply is to reduce electrical noise (or if as an exercise in electronics you want to build your own power supply without using integrated circuits, or if you ...
Kevin Reid AG6YO's user avatar
  • 24.6k
5 votes
Accepted

Powering transceiver and SWR/power meter from same supply?

This should not be a problem at all. It is commonly done this way. Hopefully the switching supply has been designed for ham radio use. If not, you may find some "birdies" on your receiver which are ...
Glenn W9IQ's user avatar
  • 18.6k
5 votes

Using an SDR on a Laptop with Noisy Power Supply

This may or may not help your particular situation, but when using a laptop power adapter, it can help to use one that is grounded. For Apple power supplies in the USA, this means swapping out the ...
Kevin Reid AG6YO's user avatar
  • 24.6k
5 votes
Accepted

How much power does an RTL-SDR draw?

To extend what hotpaw2 said: So, it seems the front panel USB sockets are maybe not providing enough power for the Dongle to work? I googled how much power the Dongle draws? and apparently it ...
Marcus Müller's user avatar
5 votes

Are there any cons of running shack on battery?

Possibly an issue with your HF CB rig is that the output power will be lower at 12.1 than at 13.8 or 14.0 volts. I've seen on 100 watt ham rigs that the final amplifier runs directly from the DC ...
tomnexus's user avatar
  • 11.3k
5 votes
Accepted

How to figure out my car battery's capacity?

There are many ways to do this. My favorite and I would assume you have these items in your shack. Most inverters have an automatic low-voltage disconnect feature. It makes a beeping sound and stops ...
Gil's user avatar
  • 283
4 votes

Power supply for shortwave portables

I wouldn't risk directly connecting a 9.6v battery to a radio that expects 5-6v. The simplest solution would probably be the diodes mentioned in the comment to your question, but as the battery ...
MoTLD's user avatar
  • 736
4 votes

How much power does an RTL-SDR draw?

I have used RTL-SDR USB peripherals from several vendors. They run at different temperatures (implying different power draws), which suggests that your question does not have a single answer. The ...
hotpaw2's user avatar
  • 13.4k
4 votes
Accepted

Regulated Power Supply vs Class 2 AC/DC Adapters

If by “a regulated power supply” you mean specifically a non-switching one as your second paragraph, then “a regulated power supply” and “an AC/DC adapter (linear, non-switching)” are exactly the same ...
Kevin Reid AG6YO's user avatar
  • 24.6k
4 votes
Accepted

How can I sound-proof my generator?

I'd argue that power law is your friend: It's probably cheapest and most reliable and least of a hazard to get a long cable and place the generator as far away as feasible, possibly behind a car, rock,...
Marcus Müller's user avatar
4 votes

Does 3 W vs 5 W TX power make a huge difference in QRP CW operation?

It makes a difference of: $$ 10 \times \log_{10}\left(3 \over 5\right) = 2.2 \:\mathrm{dB} $$ How big is 2.2 dB? See How big is a decibel? It's also relevant to note: if the 12V battery is lead acid, ...
Phil Frost - W8II's user avatar
4 votes

Are there any cons of running shack on battery?

In addition to the points raised in the other fine answers, I'd like to add a few: A good three-stage battery charger for lead-acid batteries may cost more than a power supply. Many chargers make ...
rclocher3's user avatar
  • 9,242
4 votes

Power connector for a HPA

I've seen these before, and they need to be soldered. What you have is a solder-type feedthrough capacitor with a solder-type ground lug next to it.
Mike Waters's user avatar
  • 8,023
3 votes

Practical differences between switching and linear power supplies?

You've pretty much hit the nail on it's proverbial head: Both are power supply architectures, and as such generally fulfill the role of providing a constant-as-necessary voltage source (or current ...
Marcus Müller's user avatar
3 votes

Parallel tube amplifier power supply using 6DE4 tubes

I would encourage you to reconsider this project as it not simply a matter of paralleling all of the tubes to double the output power. When you parallel more finals (807's in this case) the input and ...
Glenn W9IQ's user avatar
  • 18.6k
3 votes

Is using a generic DC 3V adapter dangerous to a radio?

A new generic AC adapter that says 3 VDC with the correct plug and the correct polarity should be safe. Almost all 3 VDC adapters will have the correct polarity; if the polarity were wrong, then the ...
rclocher3's user avatar
  • 9,242
3 votes

What sources of power are useful in emergency situations?

When they installed solar on my house, I lamented how Hurricane Sandy came, and yet all of the people having solar on their house could not use it because of the anti-islanding law(s) which say that ...
MicroservicesOnDDD's user avatar
3 votes

What sources of power are useful in emergency situations?

This is sort of an "it depends" question, and you noted that yourself in your text I believe. It will take some Q & A with yourself to come to a conclusion. First: What is the "field" situation. ...
guitarpicva's user avatar
3 votes

Is using a generic DC 3V adapter dangerous to a radio?

The 3-volt plug that works with the Eton Mini portable reciever is the Philmore # 204. Its stated dimensions are 1.3mm I.D. and 3.5mm O.D. It works!
Dick_Extra Class HAM's user avatar
3 votes

Wiring Cobra 29LTD CB for home use?

Those "wall wart" style power supplies are likely to lack the power needed here. As others point out here the radio will likely somewhere between 1.5 to 2 amps to operate as intended. I ...
MacGuffin's user avatar
  • 359
3 votes
Accepted

Does 3 W vs 5 W TX power make a huge difference in QRP CW operation?

If you haven't done much QRP operating, QRP is a funny thing. Sometimes propagation is great, and you wonder why anyone would bother with 100 W or more. I'll never forget my first DX QSO, from ...
rclocher3's user avatar
  • 9,242
2 votes

Is using a generic DC 3V adapter dangerous to a radio?

It looks as if the Eton Mini needs a 3 volt center-positive power supply. It's probably 3.8 mm OD, 1.4 mm ID barrel connector, but that's just a guess based on the half-inch depth specification of the ...
user3486184's user avatar
  • 1,947
2 votes

How to reduce voltage ripple of a linear power supply?

C (E) = I (t) E= I (t) / C C = Capacitance in uF E = Ripple Voltage, p-p I = Max Load in mA t = "7.5mSec" for 60Hz line Vpeak (.707) = Vrms Vp-p = Vrms (1.414) THEN, E = I (t) / C (in ...
Hal Mandel W4HBM's user avatar
2 votes

How to reduce voltage ripple of a linear power supply?

You do have an unregulated supply .This issue has been raised by others .You can reduce hum by increasing Your total filter Capacitance .The ripple volts is inversly proportional to Total Capacitance ....
Autistic's user avatar
  • 469

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