Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
Search
Chinese Linear R.I.P.
|
On 2021-06-08 14:11, jerry@... wrote:
All, Nope, it was the linear. Almost a dead short across the supply*** Unsoldered the final transistors - one of them tests as a MOSFET, the other one as a 1.8 ohm resistor. I'm guessing the latter is the bad one :). There is another Chinese amp that uses a real RF transistor. HOWEVER - this RF transistor is made for 850MHz up. They better have some *good* gain-killer for higher frequencies, or it'll tweet like a bird. Maybe I should just start from scratch, find a proper device and design ( or find a design ) around it? The MRF101AN looks good. It's an LDMOS device, designed for HF... - Jerry KF6VB |
|
Birdies?? I've been a ham for over 50 years.? In one of my very early days I worked a WN---- (don't recall the rest of the call). The signal sounded like he couldn't find a key, so he was pulling the canary's tail!!
Gerry Sent by the Thunderbird <SNIP>They better have some *good* gain-killer for higher frequencies, or it'll tweet like a bird.<SNIP> |
|
I was WN6EPS. It was a nice call - dit di-dah-dah-dit di-di-dit!
toggle quoted message
Show quoted text
The other day, I QSO'd a guy who was running a pair of Conar twins. Sounded just like the old days...Bwee bw-bwee-bwee-bwee. Chirps & clicks. I enjoyed it. Conar was the brand of a mail-order technician course. They ran ads in the electronics magazines showing a happy student surrounded by kit-built equipment. The school was called "NRI" ( National Radio Institute ). - Jerry KF6VB On 2021-06-08 18:26, Gerald Sherman wrote:
Birdies?? I've been a ham for over 50 years.? In one of my very early |
|
My Chinese amp uses the good ol' (and obsoleted but widely available)
toggle quoted message
Show quoted text
MRF 9120. It works fine for me. Rafael On 6/9/21 4:33 AM, jerry@... wrote:
I was WN6EPS.? It was a nice call - dit di-dah-dah-dit di-di-dit! |
|
Hi Rafael,
toggle quoted message
Show quoted text
Around 5W. Rafael On 6/10/21 3:28 PM, Rafael Pinto [PU1OWL] wrote:
Rafael, |
|
PU1OWL,
I would suggest going the attenuator route as some of the Chinese amps have a high SWR mismatch on the input.? The attenuator would reduce that to some extent. I would also suggest that you start with the SWR meter between the rig and the amp with RV1 turned down (maximum clockwise, the control is reversed) for less than a watt and slowly increase noting the SWR. For the one that I have been working on, I found it to be very sensitive to both bias and input levels.? ?I went through 3 sets of IRF520s until I got it to work.? The kit that I received could not set the bias to the correct value.? I had to modify the bias circuit.? I also put a 16ohm resistor across the secondary of the input transformer to get the SWR under control. The amp is on the shelf right now as I need to verify that 20meters is in compliance.? At the time I built it I did not have a good way to measure the third harmonic on the upper frequencies.? It was more of a how it works sort of project, as I have my Icom 7300 if I want to go QRO. You defiantly need proper test equipment to verify that the amp meets compliance requirements and the skill to use them.? It was a real learning experience for me. 73 Evan AC9TU |
Rafael Pinto [PU1OWL]
to navigate to use esc to dismiss