R7100 AC Power Verses DC

[shortride]

I read about the R7100 operating hot while powered with AC power. I was just wondering if operating the R7100 on AC have an effect on it performance compared to when it is powered on a DC power supply?

[W9BU]

Long term, maybe. Since the internal AC power supply generates heat inside the housing, that heat may have some long term undesirable effect on the electronic components. Using an external DC power supply moves the heat outside the box.

[Squad10]

During the 20+ years I've had my R7100, it has always been powered by AC. No performance degradation noted when I periodically check it with my professional grade communications service monitor.

BTW, hearing a relay click come from the R7100 when it crosses certain frequencies is normal.

[ridgescan]

My r71a runs on 125v and gets hot too. I run audio component fan to draw the heat from the AC unit out of the radio before it has a chance to float into it. Been running it for a few years now with much success. This fan in the photo runs on AC (it's a really good older quiet one) The Shack has a few different voltages in fans. I run a 12v fan on the r75.


HTH

[shortride]

I've got a nice variable power 35 amp power supply that I also inherited that I could use if I needed to.

I'm surprised they didn't mount a small fan inside of the R7100. It is true that energy is heat and heat is what usually does the most damage to electronics.

[ridgescan]

Like Squad10 indicates, I think to Icom, heat was of no serious consequence..but then I also don't think they were concerned about the units that outlive their average lifespan like ours
Only caveat about running a fan is, once or twice a year I pull the cover and gently brush out the dust that was drawn into the rig-no biggie. I figure I am prolonging the r71's life running it cooler, which goes to what you say about heat-I happen to agree 100%.

[shortride]

The cover on my R7100 has fairly limited vents. If heat was going to be an issue I would think Icom would have addressed it with more venting.

[k9rzz]

Perhaps I had a freak unit, but I ran mine on AC for years with no heat issues. So, not every unit runs hot.

[dkf435]

I want to say that I think around the time the R8500 came out the internal supply on the R7100 or another one of their receivers was removed for heat reasons or maybe just marketing By this time the remainig R7100 radios were sold on the international market as the 800-900 band window for the US model made the radios undesireable for the US market and the block could easily be removed, and the R8500 having been released and took its place.

This may be confirmed on the old Javiation UK page for the R7100A
Icom IC-R7100 (DC)

When EEB was in business they had mods for all the Icom receivers for beefing up the power supply and adding heat sinks, larger componets and cooling capacity. This was geared for professional and goverment users to make the radios last longer.

Some R7100 and also the R8500 receivers also will drift above 600 Mhz over time and will need to be tweaked back.


David Kb7uns

[CYUL]

Originally Posted by W9RXR

Long term, maybe. Since the internal AC power supply generates heat inside the housing, that heat may have some long term undesirable effect on the electronic components. Using an external DC power supply moves the heat outside the box.

I had one suffer some serious damage due to heat. Icom Canada fixed it up - changed a whack of caps etc...They told me that it was the last time they'd repair it.

I have 2 of them and a 7000, they all run hot. I may have to put fans on them like in the pic show in the thread. I want them working for as long as possible. Yet to find radios this sensitive.

[LtDoc]

If a fan is done right, doesn't introduce any significant noise into the receiver, I don't see how it couldn't be of benefit.
Inadequate cooling is something that all brands of radios have to some extent, some more than others. 'Curing' that problem is just a matter of supplying more air movement in most cases. That isn't always very simple, but it tends to work well. Some heat generation is normal. A lot of heat isn't, and isn't all that 'good' for the radio (or whatever other kind of device it is).
- 'Doc

[ratboy]

My 7100 ran VERY hot. I wasn't comfortable with it running on AC at all. It was almost as hot as my Hammarlund HQ-100, and hotter than my old Kenwood R5000, the previous solid state champ, that thing was way too hot on AC and needed a fan. That much heat can't be good for anything electronic. I have a big power supply, so I put it on that and on DC it was almost cool to the touch. I got offered a lot of money for it, and I sold it a couple years ago, but I wish I still had it.

[ridgescan]

I should mention that I not only run that fan, but I also have the rear end of the 71a slightly tilted up to further prevent heat from floating forward and collecting behind the frontend. I know the fanflo pretty much kills that but what harm is an extra measure I run fans behind the sx-88 and r75 too. The r75 is pretty sealed and runs on DC but that thing heats up pretty good too..a 12v fan I run @ 4v behind it pushes just enough air at it to get flow going and the case feels cool.