Chinese linear amp

[VK4WDM]

The well know auction site (not sure if I am allowed to post the URL?) has a 45w HF linear amp kit for $27. Does anyone know if they work?

73

Wayne VK4WDM

[VK5TX]

Aliexepress has them for $23 with free shipping

Sent from my D5833 using Tapatalk

[VK2AOH]

Checkout they have 1) reverse polarity power protection 2) high vswr power protection 3) switchable harmonic filters.

For $23

I would be most dubious

[VK5TX]

No just a basic kit. You need to build the rest. Single band amplifier for $30 can go wrong

Sent from my D5833 using Tapatalk

[VK4WDM]

I am dubious too but I am going to order one and play with it. A spectrum analyzer sweep of the output should be interesting and I expect as VK2AOH says, well built harmonic filters will be required, plus reverse polarity and SWR protection as he also suggests.

Even it turns into a Chinese firecracker the dollar loss is not going to be too much. I will report back in due course.

73

Wayne VK4WDM (We need to support the Chinese economy so they can buy more VK iron ore ).

[VK5TX]

this guy is sell the amplifier with a LPF for $28.

I have just ordered one.

http://www.aliexpress.com/item/New-45W- ... 9.7.XOKDCR

[VK4WDM]

this guy is sell the amplifier with a LPF for $28.

That looks like a better deal. It would be good to have some English paperwork to go with it.

I just noticed in the description: "need to welding yourself." Wow! must be extra heavy duty components if they have to be welded rather than soldered

73

Wayne VK4WDM

[VK3ZAZ]

this guy is sell the amplifier with a LPF for $28.

I have just ordered one.

http://www.aliexpress.com/item/New-45W- ... 9.7.XOKDCR

Screen Shot 2016-03-04 at 5.20.14 PM.jpg

Sine wave output.

Makes the eyes water to think about it and 45 watts less power than the average 6M mobile

so you drop your 100w tx to drive it?

[VK4WDM]

Hi Steve

It is designed for HF not 6m. I will pair it with a Chinese QRP 40m CW transmitter I am building. I think the Chinese should be commended for making these kits available at such a low price and thus encouraging home building. OK they might be a bit dubious, but you and I would have said the same about Japanese stuff when it first started to appear in the 1960's.

What ever the final outcome (pun intended ) it will be fun to build and play with and we need lots of fun at our age to keep the neurons firing

73

Wayne VK4WDM (A fun-seeking )

[VK5ZD]

Seems they also do a 180w amplifier for US$40.
http://www.aliexpress.com/item/180W-Lin ... 4.2.A9tDld
External filter required!

[VK5TX]

I received my amplifier kit today. They have sent the kit with out the LPF and I have contacted the seller about it.

The kit does not come with any instructions or circuit.

I will post some up dates when i start building it.

Ben

[VK3PF]

Hi Ben,

My basic kit arrived OK - not ordered with LPF. An email to seller gave details for some instructions, but the English ones are very basic....

Good luck,

Peter VK3PF

[VK5TX]

I found this circuit but is a bit small to make out.

[VK5TX]

there is a two band version now as well

http://www.ebay.com.au/itm/131660632034 ... 26_rdc%3D1

[VK4CZ]

Isn't this what you meant?

[VK3XL]

Hi Ben,

My basic kit arrived OK - not ordered with LPF. An email to seller gave details for some instructions, but the English ones are very basic....

Good luck,

Peter VK3PF

Peter any chance of forwarding the instructions you got for your kit to me please. I have not had any success getting them from the seller I bought from.

[VK4JAM]

Hi,
The kit seems to be of good quality, it can also be purchased of Banggood for AU$22.60 including shipping. Refer:
http://www.banggood.com/DIY-45W-SSB-HF- ... 18834.html

A review on the banggood site states:
"This kit meets the basic requirements for a ham kit: 1) cheap 2) fun to build 3) might actually be useful one day. As mentioned by other reviewers, there are discrepancies in the documentation. I have tried to sort these out. A full set of my build instructions, in English, will shortly be available for download on the Central Alberta Amateur Radio Club website. http://www.caarc.ca/ Meanwhile I suggest: use a 25V minimum rated capacitor for C3; when adjusting gate bias temporarily insert a 10 ohm 5W resistor in place of L1; keep meter leads connected to the L1 pads during test away from the amplifier input [hint: high gain amplifier] replace the supplied potentiometers with 10 turn trim-pots; I have taken off one quality star for all the work I had to do to update the documentation."

The documentation from caarc (16 pages) can be found at:
http://www.caarc.ca/wp-caarc/wp-content ... -V1.4-.pdf

It looks like a good way of adding a few dB to a QRP project, the addition of some band-pass filters would probably be a good idea.

73
Andrew
VK4JAM

[VK3XL]

Thanks for the link Andrew. I have a kit yet to be started (apart from machining the heatsink flat) The info from caarc looks like just the thing to get me started on the build.