[UK-CONTEST] RX antenna pre-amp

[G3SJJ]

Thanks Chris, even though you sent your reply just over two years before 
I posted my question. Dr Who?

Anyway, thanks for that. I will screen the leads and add some more 
decoupling. I've got a .01 across the 12v ip but will dob some more around.

I think though I have located the problem. I have a 4p 3w switch (Maplin 
plastic) on the front panel to go 80m - Off - 160m, for when I get the 
bandpass filters finished. It also bypasses the amp, in that it shorts 
Ip to Op when in the Off position. Looks as though there is too much 
self capacitance and it going into oscillation. If I diss the 
connection  from the input pad to the switch it all works as it should.

Getting there!   Chris G3SJJ



G3SVL wrote:
> At 21:39 15/11/2006, G3SJJ wrote:
>   
>> I have assembled a little TenTec Broadband RF Pre-amp kit No 1001 in an
>> ali box but having probs. I suspect it may be taking off. ...... 
>> Anyone got any
>> experience of this amp and how I might tame it?
>>     
>
> Chris,
>
> I have exactly the same amp and it works fine.
>
> 8cm sounds way too long for the I/O leads - the box my amp is in 
> isn't that long!  I would definitely screen them and make sure they 
> don't run parallel to each other if possible.  You might also ensure 
> the decoupling on the power supply is good - I think I added caps to 
> make sure - look on Ian's (SEK) site for decoupling theories.
>
> 73  Chris  G3SVL
>
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