June 29, 2012

Reviving FNB-17 and FNB-12 for YAESU FT-411E

I was badly missing using my favorite rig YAESU FT-411E these days as both the battery packs(FNB-17 & FNB-9) got packed up and made my Radio unusable. Problem with these two battery packs was that they are made up using Ni-Cad batteries which suffers from memory effects, it was not getting charged and it didn't had enough power to switch on the Radio. I wanted the revive this radio and put to use.

 I had many options to revive the battery packs. First I searched on ebay for replacement battery, although i found a replacement it was very expensive (priced $18 +$18 shipping, Rs 2000 INR from "imax_expert"). Then next alternative was to use a cell case (priced $15.95 + $10 shipping, Rs 1485 INR). I wanted to find a solution  locally and searched for ideas on the web. I stumbled upon Simon's 2E0HTS website(http://hamradiooperator.blogspot.in/2010/06/yaesu-ft-470-battery-modification.html) where he had cut open old FNB-10 battery pack used for Yaesu FT-470.

The choice was to rebuild the dead battery pack, now all I wanted was three 9v rechargeable batteries, connectors (clips). A quick visit to SP Road (Bengaluru) I got the rechargeable batteries for Rs250 each and few battery clips.

The most difficult part of this operation is cutting opening the battery packs which will be hard glued. we cannot use excessive force and if we do that the plastic case will break and make the case unusable. To cut open I used a small hammer and a thick piece of cloth. I placed the battery sideways on the thick cloth and covered the other side, using a small hammer I tapped the sides of the battery pack to loosen it. With a flat screwdriver I opened the case. The battery pack had (nos) Ni-Cad cells with a capacitor connected across +ve and -ve terminals. After desoldring the old Ni-Cad batteries I connected two 9V batteries in parallel.

The resultant voltage was around 17.5V~18V for which radio was not able to handle, When I switched the radio on it used to blink once and was not switching on. As the operating voltage should be 12V, I connected a 12V regulator with a heat sink and sealed the battery case and switched it on again,  FT 411E was back to life and I was able to make contact on 2m.

Next day morning which I switched on the rig with the same battery pack the radio was not switching on. A quick check on the battery pack voltage showed around 6V~7V. Looks like there has been a voltage leak without much using the radio. My other battery pack which has only one 9V battery works like charm without voltage leak. I doubted the voltage drop was due to 12V voltage regulator.

Presently I still haven't removed the 12V Voltage regulator, Hopefully I will be doing this weekend.

Keep looking this space for updates. (To be continued)

1 comment:

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