Improved HT Battery replacer

[Borage257]

I discovered some cheap Chinese radios have subpar battery replacers for "mobile' use. The plug in power supply provides enough volts and amps for receiving, but not enough amps for transmitting. After poking around I found some guys using the LM2596 DC-DC buck/boost chip to get enough power to run their HTs in a mobile or base station role. As long as the power source supplying the chip pushes more than 1.5Amps the HT will transmit. I set my chip for 8.3V and wired it to female(?) 5.5mm barrel plug for greater flexibility.

[KAF6045]

I've not heard of "battery replacers" before, but the lack of a DC input jack on these radios IS a detriment.

I'm spoiled by Amateur gear that has DC input jacks, which can be fed 13V (automotive battery level) not only to charge the battery, but even power Tx at a higher output than the battery pack sustains. Granted, the wall warts supplied with the charging bases aren't rated for full power Tx either (my recent Icom has a different wall wart for the optional charging base than the one that plugs into the radio itself. Even a 30 year old RatShack HT-202 has optional inputs: 13V on top for operations, the BATTERY pack had in input jack for charging (using apropos charger -- like 9V for a 7.2V battery], and the bottom two battery pack screws doubled as contacts for an optional charging stand [the HT-202 was a Maxon-built look-alike for an Icom IC-02AT https://www.universal-radio.com/catalog/ht/02at.html ]. Main point is that the Amateur gear provides for alternate power supply, rather than being tied to a low-power stand or dummy battery pack.

 

[Borage257]

Baofeng et al has several battery pack/power options on the market. The case I used was marketed as an AA battery pack. I sure would like to see another manufacturer come out with an affordable, modular system like the UV5R enjoys. Maybe there is one and I'm just not aware of it.  in any case it was fun to tinker with.

[Lscott]

2 hours ago, Borage257 said:

I discovered some cheap Chinese radios have subpar battery replacers for "mobile' use. The plug in power supply provides enough volts and amps for receiving, but not enough amps for transmitting. After poking around I found some guys using the LM2596 DC-DC buck/boost chip to get enough power to run their HTs in a mobile or base station role. As long as the power source supplying the chip pushes more than 1.5Amps the HT will transmit. I set my chip for 8.3V and wired it to female(?) 5.5mm barrel plug for greater flexibility.

So how much RF trash is generated by the cheap unshielded switching supply? You should run the VFO over a wide range and see if there are any noticeable increases in noise level or mysterious “carriers” that repeat at regular frequency intervals.

[Borage257]

11 minutes ago, Lscott said:

So how much RF trash is generated by the cheap unshielded switching supply? You should run the VFO over a wide range and see if there are any noticeable increases in noise level or mysterious “carriers” that repeat at regular frequency intervals.

So use another radio scanning while the chip is receiving power? The spec sheet states it has a "150-kHz Fixed-frequency internal oscillator".  Would reconfiguring the power in put and out put lead to be wrapped in ferrite chokes mitigate any RF noise? I haven't noticed any noise on 462-467 MHz range. 

 

EDIT: included ship spec sheet

https://www.ti.com/lit/ds/symlink/lm2596.pdf?ts=1656424458434

[KAF6045]

All of my Amateur hand-held units from Kenwood, Icom, and Yaesu, offer a AA (or maybe AAA for the smaller units) cases. For some radios, the alkaline cell cases trigger a lower power mode (different voltage -- four AA are 6V, six would be 9V, while the NiCad/NimH/Lion [pick your decade] packs tend to center on 7.2-8.4V. The amateur gear tends to run on variable voltage levels. The recent ID-52 is 4.5V battery case (I suspect typo in manual -- they spec output power for 5.5V, but 3xAA is only 4.5), 7.4V rechargeable battery, and 10-16V for external power -- 5W for external and rechargeable, 100mW for AA.

The Tyt -- no external power jack, nor (to my knowledge) battery cases. Might be some hidden convention for stuff that fell into Part 90 land-mobile. Anytone 878 -- no external power jack seen, but manual does show a "battery eliminator" -- which looks like a battery case with a 12V lighter plug permanently attached, and based upon the label it is really a 2/3rds capacity battery, with battery charger circuit built in; meaning the radio is operating off the battery, and the battery is being charged during the idle periods between Tx. Doesn't look too useful as the cord enters from the bottom, meaning one has to provide some form of holder with an open bottom -- might as well put velcro strips on the regular charging stand with the optional lighter adapter. Tyt and Anytone are both DMR rigs.

The wall warts for the chargers won't power radio operations. Using USB charging, the aforementioned Icom radio can operate drawing from the battery on Tx, charging on Rx and idle. Using "cigarette lighter" adapter or external 12V supply will operate it and charge at the same time. My Yaesu rigs can either operate off 12V, OR charge, but not both (seems they have the charge controller in the radio and not the battery, and the charging circuit only activates when the radio is OFF.

Apologies for what is basically a harangue/lecture...

[Lscott]

1 hour ago, Borage257 said:

So use another radio scanning while the chip is receiving power? The spec sheet states it has a "150-kHz Fixed-frequency internal oscillator".  Would reconfiguring the power in put and out put lead to be wrapped in ferrite chokes mitigate any RF noise? I haven't noticed any noise on 462-467 MHz range. 

 

EDIT: included ship spec sheet

https://www.ti.com/lit/ds/symlink/lm2596.pdf?ts=1656424458434

That would be one way. The second radio would need to be right next to the power supply. If the switching frequency is around 150KHz you would expect to see problems at 150KHz intervals. I’ve had small circuit board DC to DC converters on the bench generate enough noise to break the squelch on a hand held radio on the other side of my office stopping it from scanning. Most of the time it was on VHF I had the issue.

Ferrite cores might help if you do see problems. However having the power supply in a tightly sealed metal case would improve things too. 
 

No guarantees that you can eliminate the interference, if found, completely or to a level where it doesn’t impact operation to the point where communication is unreliable.

[Borage257]

9 hours ago, KAF6045 said:

All of my Amateur hand-held units from Kenwood, Icom, and Yaesu, offer a AA (or maybe AAA for the smaller units) cases. For some radios, the alkaline cell cases trigger a lower power mode (different voltage -- four AA are 6V, six would be 9V, while the NiCad/NimH/Lion [pick your decade] packs tend to center on 7.2-8.4V. The amateur gear tends to run on variable voltage levels. The recent ID-52 is 4.5V battery case (I suspect typo in manual -- they spec output power for 5.5V, but 3xAA is only 4.5), 7.4V rechargeable battery, and 10-16V for external power -- 5W for external and rechargeable, 100mW for AA.

The Tyt -- no external power jack, nor (to my knowledge) battery cases. Might be some hidden convention for stuff that fell into Part 90 land-mobile. Anytone 878 -- no external power jack seen, but manual does show a "battery eliminator" -- which looks like a battery case with a 12V lighter plug permanently attached, and based upon the label it is really a 2/3rds capacity battery, with battery charger circuit built in; meaning the radio is operating off the battery, and the battery is being charged during the idle periods between Tx. Doesn't look too useful as the cord enters from the bottom, meaning one has to provide some form of holder with an open bottom -- might as well put velcro strips on the regular charging stand with the optional lighter adapter. Tyt and Anytone are both DMR rigs.

The wall warts for the chargers won't power radio operations. Using USB charging, the aforementioned Icom radio can operate drawing from the battery on Tx, charging on Rx and idle. Using "cigarette lighter" adapter or external 12V supply will operate it and charge at the same time. My Yaesu rigs can either operate off 12V, OR charge, but not both (seems they have the charge controller in the radio and not the battery, and the charging circuit only activates when the radio is OFF.

Apologies for what is basically a harangue/lecture...

No problem, I'm fairly new to this and appreciate y'all taking time to educate. 

8 hours ago, Lscott said:

That would be one way. The second radio would need to be right next to the power supply. If the switching frequency is around 150KHz you would expect to see problems at 150KHz intervals. I’ve had small circuit board DC to DC converters on the bench generate enough noise to break the squelch on a hand held radio on the other side of my office stopping it from scanning. Most of the time it was on VHF I had the issue.

Ferrite cores might help if you do see problems. However having the power supply in a tightly sealed metal case would improve things too. 
 

No guarantees that you can eliminate the interference, if found, completely or to a level where it doesn’t impact operation to the point where communication is unreliable.

I've just finished running a radio vfo scan from 160.000 MHz to 170.000 MHz and didn't find anything that opened the squelch that wasn't already present in the immediate environment with the chip being unpowered.

[Lscott]

1 hour ago, Borage257 said:

No problem, I'm fairly new to this and appreciate y'all taking time to educate. 

I've just finished running a radio vfo scan from 160.000 MHz to 170.000 MHz and didn't find anything that opened the squelch that wasn't already present in the immediate environment with the chip being unpowered.

Did you mean to say powered up? If it wasn't powered up you wouldn't expect to hear anything.

[Borage257]

The power supply was receiving power while I was checking for any interference originating from it. I also checked the ambient environment with the power supply unplugged.

[Lscott]

9 hours ago, Borage257 said:

The power supply was receiving power while I was checking for any interference originating from it. I also checked the ambient environment with the power supply unplugged.

Then it seems you are one of the few lucky ones. When you get the whole thing reassembled do one more scan using the radio the battery replacer is installed on. If nothing is noticed you should be good to go.