Nucleonic Instruments

[PaulJ]

Well I did power it up yesterday....... There was no mushroom cloud, in fact nothing at all. That Tranny is dead..... It is an ex Tranny!

Paul

[Pchristy]

Dead as in no RF or dead as in no modulation? If the whole lot is dead, suspect power supply (switch, etc). Otherwise check separately for RF and encoder function.

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Pete

[PaulJ]

Pete, I do not have enough test equipment to to find out........ All I have is a frequency detector and an RF detector, both of which I just place alonside the antenna and neither show anything happening. I will try to investigate further and if I find any sign of life I will post.

Paul

[Pchristy]

So, it may just be the RF stage not working. It looks like a simple two stage (MOPA) device, so should be easy enough to fault find. A crystal earpiece, or other high-impedance headphones, placed across the signal line between the encoder and RF board and earth should indicate if the encoder is working or not. Also worth checking the current draw.

Most of the power would be drawn by the RF stage (probably 100mA or more), so I would expect the encoder to draw low 10s of mA - if that.

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Pete

[PaulJ]

Ok thanks Pete....... I'll have a play with it.

Update:- As Pete suggested, the first thing to check was the switch and lo and behold.... that was the problem! I replaced the switch and tried again and it works! The frequency meter showed it initially on 16MHz but after a while it settled on 27MHz and the Field Strength meter showed a good strong signal........

So when I do the conversion I will leave the original electronics in situ for posterity.

Paul

[RobertC]

Fantastic news !, glad you got it going

[Pchristy]

Excellent!

One of the first things I was taught about fault finding (a few decades ago!) was "always check the power supply first!".



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Pete