¿ªÔÆÌåÓý

  1. BITX20
  2. Messages
Single Messages Topics Expanded Polls

Re: Low Power - Final Amplifier on through - hole kit

 

Greetings all.

I started tracing my PA with Leonard's documentation.?



The first discrepancy I noticed right away.?

He had 30v pk-pk on the collector of Q1 (2n2218) and I only had 15.94v pk-pk. And the waveform is quite different. My guess is that the problem is around here. I double-checked all the component values, orientation of the 2n2218, and my solder joints. I'm still stumped.

Attached is a capture from the scope.?

My voltages at Q1 were as follows:?

Base: 1.79v
Collector: 10.97v
Emitter: 1.14v

And yes, I am running the entire board from a 20vDC regulated bench power supply (HP3630A), and I am feeding in 2v pk-pk at 14.00MHz from the function generator (Tektronix AFG3251).

Any insights would be much appreciated!

On Sat, Jan 21, 2017 at 6:09 PM, Jorge Luiz Fenerich <py2pvt@...> wrote:
? ?Thanks Leonard for finding this page I was needing it and I need to know also the voltages in Q1 (2N3866) if you know please pass me ok?
? ? Jorge PY2PVT _._

2017-01-20 17:17 GMT-02:00 kc0wox Leeper <kc0wox@...>:

I agree. Some of the below displays may be somewhat different as there will be harmonics at most points before the low pass filter.


I found the web page I was looking for.

This should give plenty of information to isolate a problem in the pa.

Leonard




--
? 73 de Jorge PY2PVT
? Campinas SP
? GG67MD




--
Mark Baldridge
608.561.3853

IMG_1331.JPG

Join [email protected] to automatically receive all group messages.