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Ic-t81e


#1

Hi all.

My dad (G3PJW) became a silent key about a month ago and I am now trying to sort out his radio legacy - some of which goes back almost 50 years! However, on his shelf was a more recent Icom-T81E. I have sort of charged the rig - the voltage on switch-on was showing 5v and after charge it was up to 7v. I’ve discharged and re-charged the rig a couple of times now but when pressing the ptt the rig initially transmits and then closes down after about 1 second. Receive is fine and both transmit and receive are fine when using an external dc supply. I’ve only been able to charge the rig by applying the external dc supply.

I’ve read the manual and this behaviour suggests that the battery pack may need replacing, although the manual suggests doing several charges and discharges if the rig hasn’t been used for a while (like this one). What I would like to know is if in fact this is the likely situation. Up until testing some of dad’s other gear this week, I have never operated VHF/UHF FM so please forgive my naivety (I did manage to listen to M1EYP/M through GB3MN last night though!). In the meantime I will continue with the charging/discharging cycle to see if the battery pack comes back to life.

73
Reg G3WPF


#2

I’m sorry Reg to hear that your dad G3PJW went silent key about a month ago.

Jimmy M3EYP


#3

In reply to M3EYP:

Hi Jimmy.

Thanks very much for your message - much appreciated. I guess it comes round to us all in the end. It was he who got me into radio (sound familiar?). However, back in those days (early 1960s) you couldn’t get a licence until you were 14. I spent many an operation with him on Billinge Hill (about half a mile from our house) on 160m am from the car using a kite to lift 300ft of antenna. Guess who had to climb down into the quarry to retrieve the kite and ant when the wind dropped!

73
Reg


#4

Hi Reg,

If Billinge Hill G/SP-017 was a SOTA summit back in the 1960’s you and your dad could have activated it for SOTA.

Jimmy M3EYP


#5

In reply to G3WPF:

I will continue with the charging/discharging cycle to see if the
battery pack comes back to life.

Unlikely. If it is a NiCd pack one or more of the cells will have developed fine whiskers of Nickel which act as resistors. They limit the charge current and also massively increase the self discharge rate. The whiskers form when NiCd packs are treated with care and caution. Rough charging / discharge cycles helps preserve the cells!

There is a fairly simple way to reverse the effect. Apply sufficient charging current to melt the whiskers. In an ideal world you’d be able to access each cell and find the duff one. But the pack will be all nice and sealed up and opening them can result in the nice pack being all gubbed! The best way is to take a big (70000uF or bigger) capacitor with say 48V working and charge it up to 30V. Then apply this when charged to the pack. There’ll be a huge current surge through the pack which should dislodge the whiskers. The total current should not be enough to really effect the other cells. Flash the pack a few times, if this works the pack voltage will jump. Discharge the pack and recharge it. You may need to flash it again.

If you’re lucky you should find you have a pack with around 85% of the original capacity. Do use a capacitor and not a PSU as you can spot weld the cables to the terminals which can result in “issues”. Like burning, smoke, fires, blown fuses and angry XYL’s.

It works nearly all the time. A case in point, I acquired an IC-X21 the other month which was last used in 2001. The NiCd pack would hold nothing and sat at 5.6V. After a good seeing to with a big capacitor, it now charges properly and certainly holds plenty of charge. I left the set on for 8 hours in error and the pack was still 25% charged after that.

Andy
MM0FMF


#6

In reply to M3EYP:
Hi Jimmy.

Well it was a /M operation anyway so wouldn’t have counted. You used to be able to get a car on the hill in those days!

Reg G3WPF


#7

In reply to MM0FMF:

Hi Andy.

Thanks for the tip. I will check to see if there is an appropriate c in dad’s stuff. I got rid of all mine years ago as it was “cluttering up the house”. If not, I may not bother as I’m not sure I will be using the T81E anyway.

Reg
G3WPF


#8

In reply to G3WPF:

Reg, if you aren’t sure you will be using the T81E and want to get rid of it then I may be interested.

Keith - info on qrz.com


#9

In reply to G8HXE:

OK Keith.

I don’t want to abuse the reflector and be accused of turning this into a “for sale” thread so I’ll just say I’ve noted wnat you have said!

73

Reg G3WPF


#10

In reply to G3WPF:

I do agree with that so we will leave it there.

My email address is on qrz.com if you want to contact me.

Keith.