# Tag Info

9

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 voltage. For electronic equipment you should use a regulated power supply. This requires the rectifier to produce an output voltage somewhat higher than the ...

9

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 installed in remote locations almost always use solar panels with storage batteries as their energy source. I have talked with one repeater group that supplemented ...

8

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, let's say about 20W if it's a fancy modern rig with lots of electronics and a backlit LCD. Your radio is 13.8V nominal, but it's probably rated for 13.8V +/- ...

7

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 know about that. While there are certainly people selling "RF-grade" supplies at high prices because there are people that will pay, we're not talking ...

6

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 need your equipment to double as doorstops). It is also quite possible that if you do want to reduce noise, you will be better served by adding filters to, or ...

6

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 reduce the efficiency even further. If it's a transceiver, then the receive circuitry, front panel, and transmit idle bias also takes some wattage to run.

5

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 supply, so the output power is quite sensitive to the supply voltage. So you might lose out on a few watts running from battery. This probably won't apply to the UHF ...

5

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 putting out 110AC when the battery voltage drops below 11 volts or so. You have probably encountered this feature while using your inverter. You connect a load ...

4

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 folding plug for a cord (which on recent models may not be a stock item, but should have been original equipment with yours). Any ungrounded computer power supply ...

4

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 voltage dropped the voltage reaching the radio would drop as well, and as the battery got low the output voltage after the diodes might be too low to power the radio,...

4

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 varies from model to model. Exactly, different models use different tuners, some additional amplifiers, and some use linear power supplies only, others mix linear ...

4

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 power level also seems to vary with what the device is doing (idle, streaming, sample rate, etc.) So you probably need to measure the USB current on your ...

4

This is likely a ferroresonant transformer. http://www.electroncoil.com/ferroresonant_transformers.php http://www.hammondmfg.com/CVR.htm http://www.oltronix.nl/en/ferroresonant-principle If you wanted a surge protector, a motor-generator would work pretty well. Is there a way to get rid of the moving parts of a MG? Yes. Most transformers are fairly ...

4

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, very large dog, small elephant, large elephant… Downside of long cables of course is voltage drop due to resistance in the cable. Rule of thumb: The longer ...

4

The most convenient power source would in fact be the lead-acid battery. However, not carried by hand, but in a vehicle. This provides an easy source of recharging power (just start the car), mobility to quickly relocate (driving), and the lead acid battery does have enough amperage to power most field radios (100 W+). As a lighter alternative, a Lithium ...

4

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 remnants of the switching frequency of the supply getting into your receiver and potentially interfering with desired signals or simply causing annoying tones (...

4

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, the charged voltage can be as high as 13.7. Furthermore, while a boost converter might further increase your transmit power, it's likely to make noise which ...

4

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 horrific RF noise, so you may not want to operate while the batteries are charging, or you may want to pay more for an RF-quiet charger. The actual capacity, as ...

3

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 source, for some applications, but we're most likely talking about voltage sources). Now, you can imagine a linear power supply simply as a self-adjusting ...

3

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 output impedance of the stage will decrease. This will require a redesign of the output circuit of the final stage at a minimum. If it has input filtering/...

3

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 your solar system, which usually pumps its excess power into the grid, must not do so when the grid is down, to prevent from electrocuting electric company ...

3

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. a. A literal field? b. The side of the road? c. A shelter in place situation with no grid mains? d. Pure mobile/portable on the move? Second: Based on "...

3

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 radio probably just wouldn't work. The trickiest part about finding an AC adapter is usually getting the correct plug, because there is no standard plug for 3 ...

3

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 thing. Types of power supplies There are basically only three categories of Things You Plug Into The Wall And Get DC Out: Unregulated linear power supplies. ...

3

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!

3

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 don't recall seeing a 12 volt wall wart that can provide more than 1 amp. Do you have a "soap on a rope" kind of power supply in your parts bins? That ...

3

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 Oregon to Estonia, running 11 W to a vertical, by gray-line propagation at the bottom of the sunspot cycle in 2006. Other times it seems like a complete waste of ...

2

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 radio: Since it lasts you two days on two AAA batteries (probably 1000 mAh) you can probably get by with a minimum 0.1 A (100 mA) power supply. A little more ...

2

I agree with the comment by @Johnny -- you should get fixed voltage for the ham equipment and separate lower amperage for the tinkering needs. If you are just tinkering with solid-state circuits that might need 3, 5 or 12 volts than consider one of those cheap industrial multi-voltage fixed supplies. These are switching power supplies with regulated ...

2

I would suggest an LM7805 type regulator. It will put out 5 volts for up to one amp current draw. You will need a filtered DC power source of 7 to 12 volts and a heatsink for the regulator. The 7805 regulator is quite common and very inexpensive. This type of supply is called a linear supply. It is not as efficient as a switching type supply but you avoid ...

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