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Author Topic: PS or PS + Power bank?  (Read 339 times)

KD2HPQ

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PS or PS + Power bank?
« on: October 15, 2021, 07:14:23 AM »

With my purchase of the IC-705 I am discovering the joys of QRP operation. I do a lot of operating on my back porch, plugged in.

Can anyone recommend a power supply for my IC-705? I have two low-power PSs but they are noisy. It would be great to have a PS that I can plug in while operating with AC nearby, but also unplug to use as a battery. Does such a beast exist which does not generate a lot of noise?

Also, any suggestions on reducing noise generally on these itty bitty PSs?
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WA2EIO

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Re: PS or PS + Power bank?
« Reply #1 on: October 15, 2021, 07:28:19 AM »

You will get many suggestions, but one very popular (and noise-free) unit is this one:

https://proaudioeng.com/products/pae-kx33-low-rfi-ac-power-supply/

I have used one with a KX-3 and now with my 705, and find it to work fine.


While designed with the power connector for the Elecraft KX-3, they also offer a simple adapter cable  to adapt the supply's connector  to the correct sized right angle connector for the IC-705.   It supplies 4 amps so the 705 can operate at its full 10 Watts.
There is an entire discussion on the groups.io site   but I do not know if it will come up for you unless you are subscribed to the group:  (first message at the bottom of the page; a lot of reading!)



https://groups.io/g/ic-705/topic/power_supply_for_the_705/85271186?p=Created%2C%2C%2C20%2C2%2C40%2C0&jump=1



Order through this link and get the adapter for free:

https://proaudioeng.com/kx33-low-rfi-power-supply-for-the-icom-ic-705/
« Last Edit: October 15, 2021, 07:37:30 AM by WA2EIO »
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KD2HPQ

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Re: PS or PS + Power bank?
« Reply #2 on: October 15, 2021, 08:44:21 AM »

Thanks.

I actually have this PS, and it generates noise on all the low bands. You don't see it when prop is excellent and ambient noise is already low, but it's there.

Just checked and noise is 2-3 on 160, 3-4 on 80, and 2-3 on 40.
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WA6BJH

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Re: PS or PS + Power bank?
« Reply #3 on: October 15, 2021, 12:12:29 PM »

You might want to consider a battery and a charger.  That will completely eliminate the noise.  I have a small Bioenno LiFePo battery to power my 705 and it works fine.  I have a solar panel to charge it, but you don’t need to do that.
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GRUMPY2021

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Re: PS or PS + Power bank?
« Reply #4 on: October 15, 2021, 12:22:38 PM »

Second vote for a small Bioenno battery.   Here is  one of the charts they have available.   This is for 80/20.  80% listen, 20% transmit.  Just line up the max wattage you want to transmit on and then the battery choices will show you approximate runtime.   

https://cdn.shopify.com/s/files/1/0219/0154/files/2080_Duty_Cycle_to_Runtime_Chart_07_10_2017.pdf?4250386372941725323
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KC6RCM

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Re: PS or PS + Power bank?
« Reply #5 on: October 15, 2021, 12:23:59 PM »

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N7EKU

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Re: PS or PS + Power bank?
« Reply #6 on: October 16, 2021, 06:28:05 AM »

Hi,

Icom does make battery packs just for this radio.

For the lowest-noise power supply, of course a linear supply is the way to go.  Just search ebay or similar for used 13.8V power supplies.  There are usually tons available for cheap.  I would look for a more reputable brand in good condition.

Most low amperage linear supplies however won't have over voltage protection, but one could be added by adding a circuit found in radio Handbooks.

73.
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Mark -- N7EKU/VE3

N8AUC

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Re: PS or PS + Power bank?
« Reply #7 on: October 16, 2021, 07:34:14 AM »

Hi,

Icom does make battery packs just for this radio.


73.

I thought I read where the 705 uses the same Li-Ion battery pack the ID-51 handheld DStar radio uses.
BP-272 I think it is.

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KL7CW

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Re: PS or PS + Power bank?
« Reply #8 on: October 16, 2021, 10:23:58 AM »

I have a pro audio PS and it is quiet on all HF bands with my KX2.  However, I do not think I have used it with an antenna which starts in the immediate vicinity of the actual PS. Years ago I had some "noisy" SMPS's which were noisy with an end fed antenna which started right at the rig, within perhaps a foot or so of the PS, but were quieter when the antenna (inverted v etc coax fed) were many feet away. If you use an end fed antenna, try to use at least 6 to 10 feet of coax before the matching box, and use a good common mode choke on the coax, possibly part way toward the rig, experiment. If the RFI is entering the transceiver through the DC power cable, try 10 or 15 turns  on a type 31 or 43 core.  Also it is possible that the RFI is fed back into the AC line which radiates back toward your antenna.  If the RFI is via the DC feed it is possible that it is not common mode transmission (differential mode), so a different scheme is needed.  I would first try running your rig into a dummy load and see if you get RFI, if so this will give you some clues.           Rick  KL7CW
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KU3X

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Re: PS or PS + Power bank?
« Reply #9 on: October 16, 2021, 10:38:57 AM »

Here's what I use for powering my QRP radios in the shack.

https://www.hamradio.com/detail.cfm?pid=H0-004439

It's a small 4 amp Astron Linear power supply. They are small and very clean.
Barry, KU3X
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K1KIM

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Re: PS or PS + Power bank?
« Reply #10 on: October 16, 2021, 10:44:25 AM »

You might want to consider a battery and a charger.  That will completely eliminate the noise.  I have a small Bioenno LiFePo battery to power my 705 and it works fine.  I have a solar panel to charge it, but you don’t need to do that.

This addresses your need for BOTH  battery power that can be charged by either solar or wall outlet line voltage charger/PS and a direct PS.

A self contained unit can be made from an ammo can etc that can be water tight when not being used.
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So Many Toys.......So Little Time!

N7EKU

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Re: PS or PS + Power bank?
« Reply #11 on: October 16, 2021, 12:30:52 PM »

Hi,

Icom does make battery packs just for this radio.


73.

I thought I read where the 705 uses the same Li-Ion battery pack the ID-51 handheld DStar radio uses.
BP-272 I think it is.


True yes they make it for more than one radio.  They also make an extended-reserve one too.

73 :-)
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Mark -- N7EKU/VE3

G4AON

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Re: PS or PS + Power bank?
« Reply #12 on: October 17, 2021, 01:30:54 AM »

Here's what I use for powering my QRP radios in the shack.

https://www.hamradio.com/detail.cfm?pid=H0-004439

It's a small 4 amp Astron Linear power supply. They are small and very clean.
Barry, KU3X
Glad to see Astron use crowbar over Voltage protection on all their linear supplies. You can seriously damage your expensive radio if a pass transistor in a linear supply fails, and they do fail.

I had a “wall wart” linear supply that came with a domestic audio amp fail and blow the amp, plus a CB grade 5 Amp desktop supply that I fitted with a home made crowbar board. The pass transistor failed, the crowbar circuit blew the fuse and saved my K2.

Bottom line is linear supplies are quiet, but take care to buy a properly protected one.

73 Dave
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KD2HPQ

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Re: PS or PS + Power bank?
« Reply #13 on: October 20, 2021, 12:34:50 PM »

Thanks everyone for the advice. I am going to try toroids first, then one of the protected PSs suggested here. If those ideas fail I have a 10 A-hr lithium battery that allows me to operate for the better part of a day. 20 A-h even better.

Off topic, but prop has been outstanding around dinner time every day. Noise or no noise I am getting into Europe and S. America on 5 or 10w almost every day, through my end fed antenna. The 705 is so much fun I am rarely on my 7300 any more.
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