I'm a new ham, looking to buy a transceiver that I'll use as a base
station. I want something that won't break the bank, but that will
give me room in which to "grow" as I upgrade my license. I have my eye
on the Yaesu FT-857D right now and it's gotten some good reviews on
the web.

I notice that the FT-857D's current consumption is a maximum of 22
amps, but I'm guessing that this is when transmitting with maximum
power on HF, correct? For operating on VHF and UHF, would my Astron 20
amp power supply suffice? I can always upgrade power supplies later,
if necessary, when I upgrade my license, but I'd like to think that,
if I buy the FT-857D now, I won't also have to buy another power
supply right away.

Thanks,

Steve

I notice that the FT-857D's current consumption is a maximum of 22
amps, but I'm guessing that this is when transmitting with maximum
power on HF, correct? For operating on VHF and UHF, would my Astron 20
amp power supply suffice? I can always upgrade power supplies later,
if necessary, when I upgrade my license, but I'd like to think that,
if I buy the FT-857D now, I won't also have to buy another power
supply right away.
============================
That 22 Amperes max is highly likely for more than 100 Watts RF PEP
(Peak Envelope Power) You rarely need that peak current ; the average
current being approx 8 Amperes on transmit (even with audio compression)
If you are worried that your PSU can't handle brief excursions above 20
Amperes , causing your PSU (perhaps) to shut down or the supply voltage
to drop (when your unit has a voltage fold back facility) ,you can
simply put a (sealed )12 v lead acid battery with a capacity of say 10
Amperes*Hours (AH) parallel to the PSU. The battery will then take care
of the peak current.
With a battery of say 18AH (golf trolley variety) your power supply
unit (PSU) won't need a capacity higher than 8-10 Amperes since the
battery will supply the higher current.
On receive the current will be approx 2 Amperes ,with the PSU having
sufficient excess capacity to charge the battery .

Frank GM0CSZ / KN6WH

On Oct 31, 7:55 pm, Highland Ham
wrote:
I notice that the FT-857D's current consumption is a maximum of 22
amps, but I'm guessing that this is when transmitting with maximum
power on HF, correct? For operating on VHF and UHF, would my Astron 20
amp power supply suffice? I can always upgrade power supplies later,
if necessary, when I upgrade my license, but I'd like to think that,
if I buy the FT-857D now, I won't also have to buy another power
supply right away.

============================
That 22 Amperes max is highly likely for more than 100 Watts RF PEP
(Peak Envelope Power) You rarely need that peak current ; the average
current being approx 8 Amperes on transmit (even with audio compression)
If you are worried that your PSU can't handle brief excursions above 20
Amperes , causing your PSU (perhaps) to shut down or the supply voltage
to drop (when your unit has a voltage fold back facility) ,you can
simply put a (sealed )12 v lead acid battery with a capacity of say 10
Amperes*Hours (AH) parallel to the PSU. The battery will then take care
of the peak current.
With a battery of say 18AH (golf trolley variety) your power supply
unit (PSU) won't need a capacity higher than 8-10 Amperes since the
battery will supply the higher current.
On receive the current will be approx 2 Amperes ,with the PSU having
sufficient excess capacity to charge the battery .

Frank GM0CSZ / KN6WH

Thanks. I doubt I'll have any problem in that case. I have an Astron
13.8 volt, 20 amp supply and my guess is that it'll be all I need for
now, for VHF / UHF work.

Steve
KC2SIZ

Steve wrote:
On Oct 31, 7:55 pm, Highland Ham wrote:
I notice that the FT-857D's current consumption is a maximum of 22
amps, but I'm guessing that this is when transmitting with maximum
power on HF, correct? For operating on VHF and UHF, would my Astron 20
amp power supply suffice? I can always upgrade power supplies later,
if necessary, when I upgrade my license, but I'd like to think that,
if I buy the FT-857D now, I won't also have to buy another power
supply right away.

============================
That 22 Amperes max is highly likely for more than 100 Watts RF PEP
(Peak Envelope Power) You rarely need that peak current ; the average
current being approx 8 Amperes on transmit (even with audio compression)
If you are worried that your PSU can't handle brief excursions above 20
Amperes , causing your PSU (perhaps) to shut down or the supply voltage
to drop (when your unit has a voltage fold back facility) ,you can
simply put a (sealed )12 v lead acid battery with a capacity of say 10
Amperes*Hours (AH) parallel to the PSU. The battery will then take care
of the peak current.
With a battery of say 18AH (golf trolley variety) your power supply
unit (PSU) won't need a capacity higher than 8-10 Amperes since the
battery will supply the higher current.
On receive the current will be approx 2 Amperes ,with the PSU having
sufficient excess capacity to charge the battery .

Frank GM0CSZ / KN6WH

Thanks. I doubt I'll have any problem in that case. I have an Astron
13.8 volt, 20 amp supply and my guess is that it'll be all I need for
now, for VHF / UHF work.

Steve
KC2SIZ

Hi Steve,

Welcome to HF! I'm guessing your power supply is the RS-20, the same as
mine. It has a *peak* current capability of 20A. In continuous duty, it's
rated at 16A: http://www.astroncorp.com/linear.shtml. My old Kenwood TS120S
transceiver (approximately equivalent in terms of maximum current demand)
will dim the pilot lamps on hard voice peaks and keydown CW at 100W output.
I like Frank's idea as an interim solution, though a heftier supply is a
better long-term solution.

73,
Bryan WA7PRC

Bryan wrote:
I like Frank's idea as an interim solution, though a heftier supply is a
better long-term solution.

I run an RS-20 paralleled with a deep discharge
marine battery. I not only run my IC-756PRO from
that configuration but I run my SG-500 amp at
the same time - never had any problems.
--
73, Cecil http://www.w5dxp.com

Correct. On 2M it draws about 8 Amps on Transmit...less on 70cm. HF
and 6M will draw 20 Amps or so. One thing you can do...power it from a
car battery in the ham shack. Take the battery out to the garage and
charge it every couple days (depending on how much you use the radio for
TX)...that would get you by until you upgrade to a bigger power supply.
Or...go into the setup menu and set the RF Power adjustment to
something like 50 (about half power) when you're on HF or 6M.

Scott
N0EDV

Steve wrote:

I'm a new ham, looking to buy a transceiver that I'll use as a base
station. I want something that won't break the bank, but that will
give me room in which to "grow" as I upgrade my license. I have my eye
on the Yaesu FT-857D right now and it's gotten some good reviews on
the web.

I notice that the FT-857D's current consumption is a maximum of 22
amps, but I'm guessing that this is when transmitting with maximum
power on HF, correct? For operating on VHF and UHF, would my Astron 20
amp power supply suffice? I can always upgrade power supplies later,
if necessary, when I upgrade my license, but I'd like to think that,
if I buy the FT-857D now, I won't also have to buy another power
supply right away.

Thanks,

Steve


--
Scott
http://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)