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Author Topic: LNA for HF SDR Upconverters by 9A4QV  (Read 2479 times)
N5INP
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Posts: 750




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« on: January 08, 2014, 04:13:10 PM »

Another local ham got one of his products - LNA for All - that starts effective operation at ~28 MHz. He's got another product now called LNA for HF that you can put in front of your HF upconverter used with PC SDRs. Here's the link -

Quote
The final concept deliver 19-20dB of the gain through the range from 150khz up to 30MHz.

http://lna4hf.blogspot.com/

I ordered one yesterday and I will report on how it works. The weird thing is, he asks for payment after you get the device. Wow!  Shocked

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K2GWK
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« Reply #1 on: January 08, 2014, 08:41:15 PM »

I purchased a 1 to 70 MHz amplifier kit off of Ebay for $12.95 with free shipping. If is based on the Mini-Circuits ERA-5SM. The Mini-Circuits part has a Noise Figure of 3.5dB so it is not tremendously low noise but it is good enough. I built it using a toaster oven and microscope as the SMT parts are really tiny. It does the job as a front end to an up converter for a RTL 2383U dongle.
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K2GWK Website

Stupidity for Dummies (http://stupidityfordummies.com/)

…because sometimes, you just can’t dumb it down enough…
K2GWK
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« Reply #2 on: January 09, 2014, 07:12:29 AM »

Here is a picture of the Kit.


« Last Edit: January 09, 2014, 07:15:06 AM by K2GWK » Logged

K2GWK Website

Stupidity for Dummies (http://stupidityfordummies.com/)

…because sometimes, you just can’t dumb it down enough…
9A4QV
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« Reply #3 on: January 10, 2014, 07:28:49 AM »

Hello,

As I was faced with the numerous e-mails asking for the UP-100 and later UP-125 that we stop to sell (we do have just the blank PCBs), due to the fact that there is an amplifier included in the design we decide to help all this guys this way.

Most of them already have the various upconverters where the reception using the simple peace of wire antenna is weak. We also receive requests to modify their upconverters in order to improve overall characteristics. This LNA4HF may be the simplest solution for all of them, including the guys using direct sampling method.

There is the 5 pole 30MHz cutoff low pass filter included in the amplifier design cutting the commercial TV and radio broadcast bands from saturating the upconverters and dongles.

The PCB is designed to accommodate also the other types of mmics where the same board can be also used to amplify the transmitting signal from the various sdr boards.
Various setups are possible.

The "pay later" approach is applied just because most of the guys are happy with that. They receive, test and at the end pay ordered. If they do not like the product, they can return it back.

If there is any question regarding the LNA4HF please post it, I will be glad to answer on all technical details I know.

At the end, here is the resent photo of the machine assembled batch of LNA4HF.



thanks
Adam
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