Needing a Power Supply

[Sccafire]

Here is what I will have for my basic setup for my radio in the house.

FT-8800R
Comet GP-1 or Diamond X50A Antenna mounted on roof
LMR400 50FT (roof to crawl space)(50 feet is a guess I do not know if I will need more or less)
RG-8X 3FT (crawl space to radio)

As for a power supply I do not have any idea what to purchase.

Any Help would be appreciated!

Thanks in advance,

 

[milkman21218]

I ran a FT-8800 with a 12 amp power supply. I see that you also have a FT-2900 If plan on running it you'll need a 20 amp. So I would say get a 20 amp.

 

[Ed_Seedhouse]

As for a power supply I do not have any idea what to purchase.

Well you will need a power supply that provides the voltage your radio runs on and enough amps to supply sufficient power. Power equals amps time volts, so for 12 volts at a hundred watts you need 100/12= 8.3 amperes available from the supply. You didn't specify the power you are running. You should probably allow about a 10% margin so a 10 amp power supply should handle 100 watts output fairly easily. That has to be continuous power for FM or AM.

 

[AK9R]

Well you will need a power supply that provides the voltage your radio runs on and enough amps to supply sufficient power. Power equals amps time volts, so for 12 volts at a hundred watts you need 100/12= 8.3 amperes available from the supply.

That would be true if the power amplifier in the radio was 100% efficient and the other circuitry in the radio (CPU, mic amp, display, etc.) drew absolutely no current.

Every amateur radio I've seen sold in the past 20 years clearly lists in the radio's specifications the voltage requirement and the current draw when transmitting at full power. There's no need to guess or use theoretical calculations when the manufacturer tells you what is required.

To the OP, page 2 of the FT-8800R Operating Manual lists the specifications for your radio. The voltage requirement is 13.8 volts +/- 15%. The current draw when transmitting at full power is 8.5 amps on the 144 MHz band and 8.0 amps on the 430 MHz band. I would recommend upsizing the current capacity of the power supply by at least 50% so that you aren't stressing the power supply and so you have some extra capacity for future accessories. Something like an Astron SS-18 should work fine.

 

[N0IU]

And while an 18-20 amp power supply would meet your needs now, what about the future? If you ever plan on operating HF at 100 watts, a 20 amp power supply would be the bare minimum you would need. My suggestion would be to get a 30-35 amp power supply if you can afford it. That way you will have plenty of power for your future needs without needing to buy another power supply later on.

 

[prcguy]

I agree on the Astron SS series and I use an SS-18 with an FT-8900 and also for traveling with a 100w HF rig since its small and light. In SSB mode a 100w HF radio rarely pull more than 10 amps average and I don't run FM so the SS-18 has worked fine for the last 15 years.

I also have an Astron SS-25M and an SS-30 and they have been turned on 24/7 for over 10yrs and worked great. These can be found used on Ebay for good prices and the SS-18 was only $40.
prcguy

That would be true if the power amplifier in the radio was 100% efficient and the other circuitry in the radio (CPU, mic amp, display, etc.) drew absolutely no current.

Every amateur radio I've seen sold in the past 20 years clearly lists in the radio's specifications the voltage requirement and the current draw when transmitting at full power. There's no need to guess or use theoretical calculations when the manufacturer tells you what is required.

To the OP, page 2 of the FT-8800R Operating Manual lists the specifications for your radio. The voltage requirement is 13.8 volts +/- 15%. The current draw when transmitting at full power is 8.5 amps on the 144 MHz band and 8.0 amps on the 430 MHz band. I would recommend upsizing the current capacity of the power supply by at least 50% so that you aren't stressing the power supply and so you have some extra capacity for future accessories. Something like an Astron SS-18 should work fine.

 

[LtDoc]

There are two important things to keep in mind. One of them is that you can figure the max current draw by adding the fuse sizes together. The total is what a power supply should supply. That amount will be slightly more than is actually required, but that 'overhead' is very nice to have.
The other thingy is that power supplies have two ratings, CCS, Constant Current Supply, and ICS, Intermittent Current Supply. The rating you see advertised most often is the ICS rating, which is only for very short time periods without 'popping' something, as in seconds not minutes. You are interested in the CCS rating, that's what the thing will do all day long with no problems. The ICS is typically 1/3 again as much as the CCS rating. For instance, if your radio's fuse says 8.5 amps, then you want at least a 10 amp CCS rated power supply. (You know you will power something else from that thing, so why not have a little 'overhead' to handle it, you know?) A power supply is one'a them thingys where "bigger is better". Your wallet will only scream for a while...
- 'Doc

 

[N4KVE]

I ran a FT-8800 with a 12 amp power supply. I see that you also have a FT-2900 If plan on running it you'll need a 20 amp. So I would say get a 20 amp.

What are the odds the operator will transmit on both radios at the same time?

 

[AK9R]

One of them is that you can figure the max current draw by adding the fuse sizes together. The total is what a power supply should supply.

So, if you bought a used radio and the previous owner had replaced the 15 amp fuses that the manufacturer provided with 30 amp fuses, then your method would result in you buying a much larger power supply than was needed.

Since the owners manuals for just about every ham radio rig made in the last 20 years is readily available on the Internet, finding the manufacturer's specification for a particular radio's maximum current draw is relatively easy. And, it avoids the uncertainty of using theoretical calculations or rules of thumb that are based on secondary information.

 

[AK9R]

I agree on the Astron SS series and I use an SS-18 with an FT-8900 and also for traveling with a 100w HF rig since its small and light.

For everyone's reference, the Astron SS-18 is rated at 15 amps continuous and 18 amps intermittent. Astron defines "intermittent" as 50% duty cycle.

 

[LtDoc]

Figuring the size of power supply you need, as a general rule, is just like any other 'general rule', you have to use a little thinking and the information available to you. Is adding up the fuse sizes a guarantied method? I would say it's a pretty good method, but not absolutely guarantied. But then, neither are the 'specs' in the manual. A fuse replaced with the wrong size fuse? I think that's a fairly good reason to look at a used radio under more light, don't you? And as I said to start with, this method is only one of the ways that's at least 'ball-park' 'close'.
- 'Doc

 

[WB4CS]

What are the odds the operator will transmit on both radios at the same time?

I've been known to be yacking away on 2 meters while also using RTTY or PSK31 on HF.

Also quite often I've had an automatic CW keyer sending a CQ on 20 meters while chatting with a buddy on 2 meters.

Etc. You get the idea.

 

[AgentCOPP1]

I've been getting very reliable operation from my Jetstream JTPS28M. It provides 28 max amps with 32 intermittent amps. With a 100 watt radio, you're going to want something that can do at least 20 amps. I went with the 28 amps just to be safe because sometimes your radio can actually put out more than 100 watts depending on how its innards were tuned. There are some parts of the spectrum where my radio will put out 140 watts instead of the 100 watts that it's advertised as. So basically it's best not to get a power supply that will "just barely" supply the power needed. You need to leave some room for error.

 

[milkman21218]

What are the odds the operator will transmit on both radios at the same time?

I never said TX on both radios at the same time. I said see that you also have a FT-2900 If plan on running it you'll need a 20 amp.

 

[Sccafire]

Thanks for all the information so far. I will not be running the 2900. To hard to remove from vehicle. I do not plan on going to HF. If I do it will be 5+years or more. I recently joined a club and have a member that is near me that has been a huge help. I just need something to be able to get on the air for the Nets I am involved without having to go sit in the truck.

 

[LtDoc]

I don't see where it matters if you use both radios at once. If you ever expect to use both at once, or if you should ever need a little more than the max for either radio, a little 'over-head' is nice to have. A lot of 'over-head ' is even nicer to have! A humongus power supply hurts for a little while but opens up possibilities that not having a large power supply will stop you from ever doing. It's up to you, big or little, you decide what you think might come in handy (and that you can afford).
- 'Doc

 

[k3cfc]

I have a 35 amp trip-lite and run kenwood hf------2 meter-----and a scanner all at once and have for many years with no problems. simple setup that works.

K3CFC

 

[dkf435]

Solve the problem for good just get an Astron RS-70M, or get a pair and sync them for the Icom 910H and TE systems 1450G

David Kb7uns

 

[k3cfc]

Before you use an antron you should read this first.

Introductory Information on Astron power supplies

 

[N4KVE]

I've read that article, & others. While it may be true, I just buy 1 size bigger than I feel I would need. In other words instead of buying a 20 amp unit for my HF radio which draws 20 amps on peaks, I bought a 35 amp supply. Plenty of reserve, & it's been on continually since the mid 80's. So while if they spent a few bucks more per unit to allow it to reliably supply what they claim, I just get 1 size bigger to act as a cushion, & all is well. I see plenty of good used 35 amp Astrons under $75 all the time. Can't go wrong with that.