From mstangelo at comcast.net  Fri Nov 14 12:48:17 2025
From: mstangelo at comcast.net (mstangelo at comcast.net)
Date: Fri, 14 Nov 2025 12:48:17 -0500 (EST)
Subject: [MRCG] [Milsurplus] Soviet R-107
In-Reply-To: <CO6P220MB04687AA5878AD80D418CFDDAB8CAA@CO6P220MB0468.NAMP220.PROD.OUTLOOK.COM>
References: <CO6P220MB04687AA5878AD80D418CFDDAB8CAA@CO6P220MB0468.NAMP220.PROD.OUTLOOK.COM>
Message-ID: <1421122253.723927.1763142497162@connect.xfinity.com>

Have you looked at lithium titanate batteries. They have a cell voltage of 2.3 volts. 

I haven't tried them but in migrating to Lithium Iron Phosphate batteries LiFePO4 I read about these lithium titanate LTO cells. They are safer than LiFePO4 and can be charged at a rapid rate.

Does anyone have any experience with them?

Mike N2MS

> On 11/14/2025 9:50 AM EST Ray Fantini via Milsurplus <milsurplus at mailman.qth.net> wrote:
> 
> 
> Years ago I was running a Soviet R-107 transceiver at a lot of events on 51.0 and at that time was still using the original Soviet ? Russian KNP-20 Nickel Iron or Cadmium batteries but they were always a issue at best. They produced gobs of power at 2.5 volts each but were filled with water and Potassium Hydroxide or Lithium Hydroxide or some combination of such and would leak when charging, leak when sitting around and what they leaked was some caustic substance that attacked connectors, wire or anything else that was around them. The battery compartment in the radio is lined with a epoxy or some form of paint and sealed from the radio just for that reason.
> So here we are years later and I want to start using that radio again at events. But the batteries that were stored separate are just too scary to consider at this point. The radio draws a couple hundred mills in receiver and around two amps in transmit. Although the radio uses a bunch of sub miniature tubes it has a solid state power supply for providing the 1.35 for filaments, 60 volts and high voltage of 160 volts with the added benefit of a regulated filament supply.
> All of this was designed to work on 5 volts from two sets of KNP-20 cells, the center tap of the two batteries is grounded so the radio received +2.5 and -2.5 although the inverter in the power supply did not use the center tap source from the batteries. What dose use that source is a hand full of dual coil relays that do the transition between receiver and transmit, remote control if the phone is connected and a couple other functions. Each of these dual coil relays are set up for operation on 2.5 Vdc.
> My new plan is to use a modern 6 volt 7Ah SLA cell that will fit into the battery compartment along with a diode and resistor network that provide an artificial center tap and been playing around with that but the question now is will there be an issue running all the relays twenty percent over the voltage they were using? It?s now three volts on each of the two and a half volt buses, but oddly the voltmeter on the radio that lets you monitor the two point five volt buses along with the sixty volt bus shows everything in the green.
> What?s the consensus about operating things at 120% ? They do have a regulator built into the filament bus so not worried about that and feel that the one thing that the old soviet system did well was over design components and this may not be an issue for the relays in the radio.
> What do you think?
> 
> Ray F/KA3EKH