RAM Radio Experiments


The Cell2Jack

Cell2Jack on my desk

Copyright © 2021, Ramon Gandia, AL7X


October 20, 2021 -- Cell2Jack

The new current/voltage meters for USB arrived, and I put two of them to use. One measures total into the cell2jack (C2J) and in turn to the phone. The other one measures only what goes to the phone.

As stated below, the power from the C2J to the phone is 'blinked' when something happens. Because of this, I do not think it is wise to power the phone separately.

When I got the power meters, I also switched to an older Galaxy S4 phone. Initially the current was high, but after a few hours, the phone fully charged. After that the current went surprisingly low. Making or receiving a call made the current spike, but not bad. Once the call is over, within a minute or less, the current goes to a very low value.

  • Total Current, Idle = 0.14 amperes. On 5v USB bus.
  • Phone only, Idle = 0.03 amperes. On 5v USB bus
  • Later on I will have draw from a 12volt charger.
  • Phone, many apps deactivated
  • Screen set to deactivate after 15 seconds inactivity.
  • Screen brightness set about 30%. Usable indoors.

In a few days I am going to clear my desk of this mess, put it out of the way with just the phone on my desk. I will maybe try access the phone once in a while, maybe a month or two apart, see if it disconnects or unpairs. I expect all will be smooth sailing.

October 17, 2021 -- Cell2Jack

For the past week, the bluetooth connection from the C2J to the Galaxy s10e has been flawless.

Today, I pulled the s10e, and instead paired an old Galaxy S4. It connected without issues and 8 hours later still perfect.

The S4, after a few hours, settled to 0.2 amps (C2J+S4), and making a call boosts it to 0.8 amps. Hanging up stays around 0.5 for a while, then tapers to 0.2 eventually.

I think the S4, being old, with an old battery, takes most of that charge and converts it to heat. It takes HOURS to charge from 50% to 100% and gets hot. I fear what would happen if this phone (or any phone for that matter) stayed on the charger for 12 months out of the year.

S4's are pretty old, and not worth much. This one here is in pristine condition, being shelved about 5 years or more ago. So ... got some ideas.

Been reading on the web about bypassing the battery and shooting the volts right into the phone. Just removing the battery does not work; the battery has to be simulated.

What I read is to take an old battery, gut it so only the connection pins remain, and hook up to that. I am going to try this. The S4 should be safe; I got some other batteries here, and of course, the S4 is one of those precious phones that have removable batteries.

Stay tuned!

October 13, 2021 -- Arcom RC-210 Controller

This controller appears ideal for our ham radio purposes, regardless of what repeater radio we hook up to it.

Power draw is only 70ma

Can connect three radios, or two radios and IRLP.

Any port can be connected to any other port as needed.

Located at the Hub, only one radio to port1

Located at the proposed hub location on Newton; the Newton VHF repeater would be on port2, the hub UHF repeater on port1. The present linking UHF transceiver on Newton would not be needed as the connection is by wires from the VHF unit to the Arcom.

Temperatures and voltages can be read on demand by sending touch tones to it. Switch sensors like Door open, etc. are available, and relay controls such as "Turn on the Solar Panel Deicers for one hour" is available.

Phone autopatch, of course.

I am currently digesting the manual to learn more of its features.

Stay tuned!

Trying out The Cell2jack

October 13, 2021 -- Phone and Cell2Jack

I am undertaking some electrical power consumption and reliability testing

I have tried Samsung Galaxy S10e, LG-K50, Motorolo Moto G Power and Samsung J3.

For power I cooked the phones with a USB metered cord. The J3 was horrible, and the Moto G Power was also high. These phones were drawing 0.7 amperes hours after they reported 100% charge. While the J3 was old, the Moto G is a brand new phone. Most discouraging.

The s10e and the LG-K50 close. The LG drew a bit less after charging, but took longer to charge. The s10e charged very quickly. They are in the 0.1 to 0.2 amp range per phone.

The Cell2Jack by itself is 0.1 amps

My metering setup is not very accurate, so I ordered a more accurate USB power meter. 4-digits instead of 3 digit. The crude tests quickly weeded out unworthy phones!

The Bluetooth was only tried with the s10e. The LG was only measured for power draw. So far, the BT has proven s100% reliable. One curious thing I noticed. Whatever phone gets power from the C2J also gets a "signal" on the power cord when the phone is lifted off the cradle. For instance, with the s10e on bluetooth, and either not charging or charging from a separate charger, calls went in and out normally.

If a phone is charging from the C2J, even though it is not BT connected and thus not making calls, the screen come alive out of sleep mode the instant the phone is lifted from the cradle. I am guessing this is "wake up" signal from the C2J to the phone in case it has gone into deep sleep.

In all cases I had WiFi off, and the screen dimmed but not so much that it could not be read. There are other power saving features on these phones that I have not explored.

There is an APP called "Package Disabler Pro", that I had on a former Samsung Note 10 that I had. Disabling a lot of the bloatware that comes with Samsungs extended the battery life from about 10 hours in normal use, to two days of use. I intend to get this APP to work on these phones as well, but I am not ready yet.

Stay tuned!

October 10, 2021 -- Cell2Jack

This units enables a conventional desk phone to work out via a cell phone. No landline needed.

In the picture you see the cell phone, the cell2jack, and a regular desk telephone. Pick up the phone, get a dial tone. Dial out. The call goes out the cell phone to whatever number you dialed. Works as advertised. I had no trouble reaching any phone, or being called by anyone.

Why is this significant?

The radio repeater phone patch behaves EXACTLY like the desk phone shown. Thus, the cell2jack can replace the TelAlaska landline. Meaning any repeater needing phone access is no longer tied to a location where landline service is available.

Look carefully: The three wires going to the unit.

  • Phone Cord from desk phone to the cell2jack.
  • Center: cord going to a micro-usb standard phone charger.
  • Charging cord for the phone.

The phone being used for the test is Samsung Galaxy s10e. I have reduced screen brightness to conserve power.


  • Q. Power. Is it excessive for solar?
  • A. Tests indicate about 0.2 amperes at 5 volts for both the Cell2Jack and the Cell Phone.
  • Q. Low Temperatures?
  • A. Touching the unit, feels warm. If the unit and cell phone were on an insulated pouch, both would stay warm.

  • Q. Bluetooth?
  • A. The wire going to the phone is for charging only. The actual voice calls go from cell2jack to phone via bluetooth.

Over the first 72 hours bluetooth connectivity did not get interrupted. Latest generations of B.T. are much more reliable than the older ones.

After 24 hours, I had to move things on my desk, and depowered it. After a few minutes, I fired it up. Within 60 seconds, the bluetooth Connection reestablished itself with no issues. Welcome news indeed!

I unplugged the phone from being charged, and the draw from the cell2jack dropped to half, 0.1 amperes at 5 volts. I will be trying several different phones.


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Copyright © 2021, Ramon Gandia, AL7X
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