Power Supplies?

Status
Not open for further replies.

arktisfox

Member
Joined
Feb 7, 2011
Messages
5
Location
Rochester, NY
Greetins,

I am looking at picking up a power supply for a FT-897D and would like some feedback on what's good and what's not for what's available. My parameters are 13.8volt, 30AMP (20 continous), with meters. I have read many reviews on QJE, Jetstream & Alinco's flavors and I am just not that convinced that these are the best way to go. I will use the PS mainly for home use, so it does not need to be a traveling model, I would like a tried and true... rock solid PS. Any input is appreciated for this newbie is appreciated. Thanks.


-arktisfox
 

N4KVE

Member
Joined
Mar 1, 2003
Messages
3,119
Location
PALM BEACH, FLORIDA
Get an Astron Linear power supply. A heavy one with a big transformer. If you needed one to travel, I'd say get a switcher, but since it's for the house, get the RS35M. Switchers can cause birdies while receiving all over the HF band, however for VHF, & UHF, switchers are just fine. I've used my RS35M for almost 20 years, & it's been on 24/7, except for moving day. While they are $169 new, I see them all the time for $100 used at ham fests. They will run your Yaesu all day long without breaking a sweat. I usually keep a cheap computer fan blowing on the heatsinks for extra cooling, but it's not really necessary. The above SS30M is an excellent supply, & I have 2 of them, but I only use them for VHF/UHF. Linear supplies for HF. Go to EHAM.NET to read about any ham radio product you want. In this case go to the power supply section. Don't cheap out on the power supply. You get what you pay for. GARY N4KVE
 
Last edited:

W9BU

Lead Wiki Manager
Super Moderator
Joined
Jul 18, 2004
Messages
6,163
Location
Brownsburg, Indiana
My vote is for Astron, too.

One issue with Astron's to be aware of, though. The design of some of their linear power supplies causes the heat sink fins on the back of the PS to be electrically "hot" (at the regulated DC voltage, NOT 120VAC). If anything touches those fins that can complete a circuit back to the negative terminal of the PS, you'll get a short circuit and some sparks. Happened to me when the shell of the coax connector on the back of a radio accidently touched the fins of an Astron RS-20.

Astron may have fixed this in later designs. If they did, great. If they haven't, be careful about grounded objects touching the heat sink fins.
 

prcguy

Member
Joined
Jun 30, 2006
Messages
9,048
Location
So Cal - Richardson, TX - Tewksbury, MA
I'll second the Astron SS switcher series, I have several and they do not have any detectable birdies on HF.
prcguy


Get an Astron Linear power supply. A heavy one with a big transformer. If you needed one to travel, I'd say get a switcher, but since it's for the house, get the RS35M. Switchers can cause birdies while receiving all over the HF band, however for VHF, & UHF, switchers are just fine. I've used my RS35M for almost 20 years, & it's been on 24/7, except for moving day. While they are $169 new, I see them all the time for $100 used at ham fests. They will run your Yaesu all day long without breaking a sweat. I usually keep a cheap computer fan blowing on the heatsinks for extra cooling, but it's not really necessary. The above SS30M is an excellent supply, & I have 2 of them, but I only use them for VHF/UHF. Linear supplies for HF. Go to EHAM.NET to read about any ham radio product you want. In this case go to the power supply section. Don't cheap out on the power supply. You get what you pay for. GARY N4KVE
 
K

kb0nly

Guest
My vote is for Astron, too.

One issue with Astron's to be aware of, though. The design of some of their linear power supplies causes the heat sink fins on the back of the PS to be electrically "hot" (at the regulated DC voltage, NOT 120VAC). If anything touches those fins that can complete a circuit back to the negative terminal of the PS, you'll get a short circuit and some sparks. Happened to me when the shell of the coax connector on the back of a radio accidently touched the fins of an Astron RS-20.

Astron may have fixed this in later designs. If they did, great. If they haven't, be careful about grounded objects touching the heat sink fins.
you sure about that?? I haven't seen an Astron yet, and i have worked on OLD units to current production, that had the heatsink at the positive voltage. Its possible if you had a failed component, but highly unlikely as the heatsink is not electrically insulated from the rest of the supply for heat transfer as well, so you couldnt have a positive voltage on the heatsink unless you had a component failure AND your power supply wasn't grounded properly at the outlet or with an earth ground. Actually now that i think of it you couldn't anyway as any leakage to the heatsink or cabinet would short it out and pop the fuse anyway as the regulator is at case potential for its ground.

I dumped my Astrons years ago and went with a large Switching supply, an Iota 55a continuous duty, no birdies that i have found on HF.

We have some 75a units running two repeater sites, rock solid supplies.
 

prcguy

Member
Joined
Jun 30, 2006
Messages
9,048
Location
So Cal - Richardson, TX - Tewksbury, MA
I have not encountered an Astron with an electrically hot heatsink but all the pass transistors are exposed, hot and have a potential of around 19 to 22v. If your grounded coax connector hits one of these it will create some fireworks.
prcguy


you sure about that?? I haven't seen an Astron yet, and i have worked on OLD units to current production, that had the heatsink at the positive voltage. Its possible if you had a failed component, but highly unlikely as the heatsink is not electrically insulated from the rest of the supply for heat transfer as well, so you couldnt have a positive voltage on the heatsink unless you had a component failure AND your power supply wasn't grounded properly at the outlet or with an earth ground. Actually now that i think of it you couldn't anyway as any leakage to the heatsink or cabinet would short it out and pop the fuse anyway as the regulator is at case potential for its ground.

I dumped my Astrons years ago and went with a large Switching supply, an Iota 55a continuous duty, no birdies that i have found on HF.

We have some 75a units running two repeater sites, rock solid supplies.
 

W2NJS

Member
Joined
Mar 27, 2006
Messages
1,938
Location
Washington DC
Astron, end of story. They will also respond quickly and politely to any and all requests for parts, boards, transistors, etc. if and when you ever need them. The weight of a 20 or 35 Amp. transformer supply of theirs is a killer if you have to lug it any distance, but they're worth the trouble. I run both kinds of supply and find them to be reliable and long lived.
 

W9BU

Lead Wiki Manager
Super Moderator
Joined
Jul 18, 2004
Messages
6,163
Location
Brownsburg, Indiana
I have not encountered an Astron with an electrically hot heatsink but all the pass transistors are exposed, hot and have a potential of around 19 to 22v. If your grounded coax connector hits one of these it will create some fireworks.
Thanks for the clarification. It was a small power supply, maybe an RS-12 or RS-20, and I recall that the transistors were more exposed than they would be on a larger PS that has larger fins. Maybe I should check to see if my VS-35M has the same problem. :wink:

I now use a small Astron switching PS (SS-25) for my VHF/UHF rig.
 
K

kb0nly

Guest
I have not encountered an Astron with an electrically hot heatsink but all the pass transistors are exposed, hot and have a potential of around 19 to 22v. If your grounded coax connector hits one of these it will create some fireworks.
prcguy
Hmm, i just grabbed a RS-20 and a RS-12 off the shelf here, repaired both of them for a fellow ham and hes coming to get them in a week... I checked both of them and the transistors are not at a positive voltage on their case. There is a mica insulator between them and the heatsink on older units so i guess the older ones had transistors with a case at positive voltage. These two are not. Must have been a design change over time.

Never noticed it before as i never had a problem with any in that way, new or old. I have had a lot of dead Astron's over the years though. They have a lot of failures and problems, but those are usually well documented on the web and you can do a few minor mods to alleviate these problems.

Another thing the OP needs to watch for. Don't buy an Astron based on its rating, for example an RS-20 is only a 20a surge, its about 16a continuous and thats working the heck out of it. You need to go a step or two above of what you need. If you need 20a your going to have to buy a RS-35 at least.
 

W9BU

Lead Wiki Manager
Super Moderator
Joined
Jul 18, 2004
Messages
6,163
Location
Brownsburg, Indiana
There is a mica insulator between them and the heatsink on older units so i guess the older ones had transistors with a case at positive voltage. These two are not. Must have been a design change over time.
My RS-20 that has the problem is over 20 years old. I seem to recall a design change being made or a mod circulated in the ham community that fixed the problem.

I've never had an Astron fail, but I also never run them beyond about 80% of rated continuous current. And, as you note, Astrons are rated based on instantaneous current and the continuous current rating is sometimes not so obvious in the advertising.
 
Last edited:

JeremyB

Member
Joined
Jan 9, 2009
Messages
170
I have a RS-35M and use it with a Yaesu 857D. The meter lighting pulses with power output and doesn't bother me. These are built heavy duty
 

N4KVE

Member
Joined
Mar 1, 2003
Messages
3,119
Location
PALM BEACH, FLORIDA
A little tip for the switchers. I did this on my SS30's & it works great & takes 5 minutes. The cooling fan runs real fast when it kicks on, & can get quite noisey. Go to the Shack & pick up a few 1/2 watt 100 ohm resistors. Install one across the temp sensor on the right side heat sink. This will give juice to the cooling fan so it will run all the time, but slower, so no noise. Should it get warm [which has never happened yet] the sensor will connect, & the fan will spin at normal speed until it cools. This mod is good for all the switchers, & definately cuts down on the noise. GARY N4KVE
 

davidgcet

Member
Premium Subscriber
Joined
Aug 17, 2010
Messages
1,264
astrons that have the hot case are those that someone worked on it and either installed the transistors without the insulators on the legs or with a broken mica insulator. the chassis is not the DC ground, ao a DC+ short to it won't necessarily trip them out. i've also seen it happen where the transistor case was hot due to an internal short in the transistor. usually those power supplies won't hold up to rated draw, since part of the finals it basically dead.

and you think the 20-30A models are heavy, i have a few 60A rack mounts that will show you what heavy is! but them things will hold up to a beating.
 

prcguy

Member
Joined
Jun 30, 2006
Messages
9,048
Location
So Cal - Richardson, TX - Tewksbury, MA
The sizing also depends on the use. For an unattended high current application like a repeater site you would probably up size and at least double the continuous current rating like using a 50A or 70A Astron for a repeater that draws 20A.

For amateur use and especially SSB the current draw is not much, maybe 6 or 8A average for a 100W HF SSB radio. Even in FM mode at 100W your intermittently using about 20A with some cool down time in between transmissions so a 20A intermittent duty model is fine for most hamsters.

For motel hopping use I settled on an Astron SS-18 switcher which is only rated for 18A intermittent and less continuous. This is a really small and lightweight power supply that travels nice and I've thrashed this thing for many years with 100W radios and it never fails and it only cost me $30 used. I believe TenTec also sold this same supply for use with their 100W HF transceivers, so there are a few exceptions to the over sizing rule.

I've also used the Astron SS-25M and SS-30M continuously for the last 10yrs or so and they have been very reliable running 24/7. You can find lots of Astron SS series power supplies used for very reasonable prices on Epay.
prcguy


Another thing the OP needs to watch for. Don't buy an Astron based on its rating, for example an RS-20 is only a 20a surge, its about 16a continuous and thats working the heck out of it. You need to go a step or two above of what you need. If you need 20a your going to have to buy a RS-35 at least.
 

prcguy

Member
Joined
Jun 30, 2006
Messages
9,048
Location
So Cal - Richardson, TX - Tewksbury, MA
Only if your broadcasting continously without letting up and yes a 100W radio in FM or digital mode running from a 20A Astron would probably overheat and break under those conditions.

However, most hams (excluding elderly ones that frequent AM nets) usually unkey to take a breath or let someone else talk after a minute or two and the same holds true for typing in digital modes. That would be closer to a 50% duty cycle for the duration of the conversation.
prcguy




You forget digital modes on HF can approach 100% duty cycle. That can very easily pull the maxmium current.
 

mrweather

Member
Joined
Dec 19, 2002
Messages
930
I've got an Alinco DM-330MV that's been running 24/7 for almost six years without a hiccup. I haven't noticed any extra noise on HF either.
 

K9WG

Member
Joined
Nov 12, 2010
Messages
1,366
Location
Greenfield, Indiana USA
Only if your broadcasting continously without letting up and yes a 100W radio in FM or digital mode running from a 20A Astron would probably overheat and break under those conditions.

However, most hams (excluding elderly ones that frequent AM nets) usually unkey to take a breath or let someone else talk after a minute or two and the same holds true for typing in digital modes. That would be closer to a 50% duty cycle for the duration of the conversation.
prcguy
B-u-t I t-y-p-e v-e-r-y s-l-o-w. . . . :D
 
Status
Not open for further replies.
Top