New User: Flex 8400 Current Draw?

kq4tnf

I am about to do the deposit on the 8400 but wanted to see if anyone knows what the current draw is on the 8400? I did not see that information on the spec sheet. Im wanting to plan the purchase of a power supply for this and am trying to figure out what size to get.

KD0RC

I am a fan of buying more power supply than you need to accommodate additional gear. I am way overkill with a 70 amp Astron, but a 45 amp unit will fill the bill and provide enough headroom for just about anything else that you might want to power in your shack.

Mike-VA3MW

Here is what we recommend.

Using a 20A Astron is not recommended for full power operation.

25A is highly recommended and the PowerWerx we sell does a great job (I power both a 6500 and a 6600 at the same time). This is the minimum current rating.

And, of course, anything greater than 25A is not a bad idea either. It depends on your budget.

Chris DL5NAM

Is it your first 100W TRX for Short Wave?

PSU like all other TRX on market if the have a max. output off 100W = PSU with 25 - 30 A !!!!

Chris DL5NAM

Al K0VM

Same as 6400.. 25-30 amps on transmit.

AL, K0VM

Neil D Friedman N3DF

The PSU Flex sells, 25 amps continuous, 30 amps max, is entirely adequate.

kq4tnf

Yes to the questioin on this being my first trx! looking forward to this

Johan SE3X

As Len I prefer a bit of headroom and use a 50A for my 6700. If you are running barefoot 100W a 25A will have to work hard, a 45-50A not so much.

73, Johan

Neil D Friedman N3DF

Been using Flex’s 25 amp PSU daily for 6.5 years, sometimes for weeks at a time, without a whiff of a problem.

John KB4DU

Average power draw depends on mode. SSB is very peaky, averages about 30% power overall, if peakes are at max power.

Ken Wells

If I had more than one radio, I would rather have TWO 25-30 Amp supplies than ONE 50-60 Amp supplies….

WHY? Of one of them goes bad, you still have one that will power at least one of your radios, keeping you on the air.

Johan SE3X

Agree 100% with you Ken, redundancy is very important. That's why I have my 50A connected with only 20cm wires from the PS to the radio. To minimize losses betwen PS and radio and my main PS.

Then I have a second 30A PS powering things like remote switches etc. that in case of a main 50A PS failure could be switched in to my 6700 in less than 2 minutes.

Is it likely that both goes bad at the same time? Well maybe after a thunder strike? But I guess than the station might be history anyway.

Neil D Friedman N3DF

I guess I’m just lucky, but in almost 60 years as a ham I’ve never had a power supply fail (other than a bulb on an Astron lighted meter model).

ka9ees

My 40 yr old Astron RS35M failed a few months ago. Transformer primary developed a dead short. So it does happen.

Mike-VA3MW

All my Astrons have failed now. :) Some lasted 20 years, some less.

Needless to say, I don't own any of them anymore.

ka9ees

I like Astron supplies. I now have a rebuilt Astron 35M rack mount. It had a shorted pass transistor, and a 30 amp Powerx as a backup.

Russ Ravella

Yeah, Astron makes great power supplies. They have been in wide use in the ham community for many years. If they weren't well made they'd have a poor reputation rather than the long history of great reviews they have. Of course, they have to be competently used like anything else. I have several of varying types and sizes. Never had the slightest problem with any of them. The RS-70 linear is a beast with essentially unmeasurable ripple and noise. Amazing.

73 Russ kR6W

Mike-VA3MW

Russ, you should check the pricing of the RS-70 now. It is well over $550 and since it weighs about 50 pounds, they don't ship it for free. :)

But, yes, it has a 5mv ripple compared to most that have <100mV (p-p). Is it worth it? As an operator, would a 100mv ripple impact my daily operation in any way?

Russ Ravella

Mike,

No, I doubt it would. But of course, that's quite clearly not the point.

The point is, Astron makes good power supplies. An attribute of a good power supply - especially one whose major design advantage is intrinsically low noise as with linear power supplies - is low noise. And as I said, the Astron RS-70 has low noise. As an aside, I suspect your "5mv" noise statement. I'm not aware of anyone credible having measured it, including Astron who after trying several times states it's below their own measurement capability threshold. Not that it couldn't be done of course. Just that I'm unaware of it having been.

As for the price, as anyone at Flex will tell you (and I'll bet a scrub of ham postings would turn you up more than once), you get what you pay for. Which of course, is true.

Russ KR6W