View Single Post
Old 7th Nov 2013, 11:23 pm   #15
G0HZU_JMR
Dekatron
 
Join Date: Sep 2010
Location: Cheltenham, Gloucestershire, UK.
Posts: 3,077
Default Re: Marconi 2022C - Stopped working below 62.5 MHz

Quote:
Originally Posted by Stefan_O View Post
I replaced the IC2 OM345 with 1nF and it works!!! Thank you very much!
That's good However, I do think you have to fit an amp here at some point because the lack of buffering might cause subtle issues with spurious responses. That buffer provides a very useful degree of reverse isolation for one thing.

To show you the advantage of the better transistor (eg the BFR540 suggested by David) I ran the simulation in the later version of Genesys because it has this BFR540 model in the library.

You can see that the performance at 160MHz is about the same but you can see how much better the BFR540 is at maintaining a good input match and it should perform better at higher frequencies.

http://media2.turbosport.co.uk/2013/...OM345_160c.gif
__________________
Regards, Jeremy G0HZU
G0HZU_JMR is offline