Pages: [1] 
|
 |
|
|
Author
|
Topic: Low drive, 10 meters (Read 1941 times)
|
|
WD8BXS
alter Hase
 Offline
Posts: 286
|
 |
Low drive, 10 meters
« on: 22. September 2020, 17:53:14 »
|
|
I have one (mcHF) on the bench, and it has low drive on the upper bands.
It has similar signals at the output of T5 on all bands, but on the upper bands there is low output on the drivers Q3 and Q4.
I have tried new ones, but same result.
I have another radio here with the same type drivers and it does not show the same results, it has good driver out put on the upper bands.
Any ideas??
Tnx, Chuck
|
| « Last Edit: 22. September 2020, 22:14:24 by WD8BXS » |
 Logged
|
Thanks,
De WD8BXS vy 73
|
|
|
|
|
WD8BXS
alter Hase
Offline
Posts: 286
|
|
Re:Low drive, 10 meters
« Reply #2 on: 23. September 2020, 12:39:45 »
|
|
Hi Andreas,
Yes, that is what I am doing.
That is how I have arrived at these results.
I have good signals to driver input.
Low signal on driver output on 17 meters and up.
|
|
Logged
|
Thanks,
De WD8BXS vy 73
|
|
|
|
|
WD8BXS
alter Hase
Offline
Posts: 286
|
|
Re:Low drive, 10 meters
« Reply #4 on: 23. September 2020, 16:31:17 »
|
|
Yes, I desoldered the 2 100nf and no change.
I will examine the other part values.
I have tried 2 new transistors, could all be bad??
Chuck
|
|
Logged
|
Thanks,
De WD8BXS vy 73
|
|
|
|
|
WD8BXS
alter Hase
Offline
Posts: 286
|
|
Re:Low drive, 10 meters
« Reply #6 on: 23. September 2020, 23:29:49 »
|
|
Bought from Mousers
|
|
Logged
|
Thanks,
De WD8BXS vy 73
|
|
|
DF8OE
Administrator
Offline
Posts: 6289
Stellvertr. OVV I40, Jugend / Nachwuchsreferent
|
|
Re:Low drive, 10 meters
« Reply #7 on: 24. September 2020, 05:00:20 »
|
|
Mousers, Digikey, Farnell do not sell fakes. You have definitely one of the other mentioned issues. For bug hunting you need in optimum a spectrum analyzer (for looking what you are amplifying), an oscilloscope (signal amplitude checking), a DVM (checking DC states at drivers, checking BIAS of drivers), an inductor tester (or VNA) for checking health of collector inductors.
vy 73
Andreas
|
| « Last Edit: 24. September 2020, 05:00:39 by DF8OE » |
Logged
|
Wenn der Wind des Wandels weht, nageln die einen Fenster und Türen zu und verbarrikadieren sich. Die anderen gehen nach draußen und bauen Windmühlen...
qrz.com-Seite von DF8OE
-----------------------------------------------------
>>>> Die Inhalte meiner Beiträge dürfen ohne meine explizite Erlaubnis in jedwedem Medium weiterverbreitet werden! <<<<
|
|
|
SP9BSL
positron
alter Hase
Offline
Posts: 443
|
|
Re:Low drive, 10 meters
« Reply #8 on: 24. September 2020, 07:08:01 »
|
|
Hi,
I would suggest to check the collector coils, 47uH often has self resonance around 10MHz. Try to insert lower value coil for experiment, let's say 4.7uH and check if the higher bands signal level rise.
|
|
Logged
|
73 Slawek
|
|
|
Pages: [1] 
|
|
|
|
|
|
|
