New model of BG7TBL noise source


#1

I noticed today that there is a new version of the popular BG7TBL noise source dated 2016-02-06. Prior to this the most recent version I had seen was 2014-08-20, and those often had a limited life span due to excessive heat. There are many of the usual Chinese vendors selling this new model, as well as many still selling the 2014 model.

The amplifier chips appear to be different, and the new one doesn’t have the electrolytic capacitors like the old one did.

I’m curious if anyone has tried this new model and found any improvements, and if anyone knows what the amplifiers are that replaced the three ERA-5+ chips used on the 2014 model?


#2

Do you mean this one? Havn’t tried it but is still pulling around 160ma, maybe a bit less than the older BG7 ones but it is still going to get fairly hot.
I have one of the origional BG7 here that has had quite a bit of use over the last 6 months and is still going strong but they do need a fan mounted to the board.


#3

I purchased the one in picture below last year.
It failed after one week.
It generated so much heat that during it’s one week life, I used it for frying eggs. :smiley:


Roll your own Interdigital filter
#4

That appears to be a different, more costly one. Here’s a link to the one I saw:
http://www.aliexpress.com/item-img/NEW-SMA-noise-source-Simple-spectrum-external-tracking-source-DC-12V/32563969427.html
I have the 2014 model and am in the process of replacing the amplifier chips, and adding heat sinks and a fan. Hoping to preserve it better this time.


#5

After bitter experience of noise-source, I have decided to purchase a Signal Generator:

Low Cost Signal Generator (35Mhz-4.4Ghz) for antenna testing

.


#6

Has anyone used any of these Signal Generators?


#7

@yxespotter
The one you linked to looks like it needs a 300ma power supply so it will probably generate the same heat as the old ones.
My 2104 model one has been fine with just the fan so with the heatsinks as well, your repaired one should go for years :slight_smile:


#8

This remedy came too late for me. Unfortunately my Noise Source is already dead. If I only knew before it’s death, my Noise Source will be alive today…

Anyway I am now considering a low-cost Signal Generator, as it will enable me to measure the SWR of antennas, whereas noise source does not.


#9

@abcd567, It was probably the demise of your noise source that alerted me to the issue in the first place, so thanks! (if thats any conciliation :slight_smile: )

The noise source and directional coupler does the SWR ok, for what I need anyway. Measuring an open feed line gives you infinate’ish SWR then a good 50ohm dummy load gives ~1:1, the rest can be converted from the db scale between these points. Its probably as good a number as any uncalibrated non professional gear is going to give.

I think I mentioned this previously and I know you are quite familiar with the effects of standing waves. But I’ll rant on anyway. The main thing I found in getting useful results that isn’t mentioned in all the YouTube videos etc, is keeping the feed-lines as short (preferably non existent) as possible. It’s hard enough coming to grips with the results when not having to get your head around the effects of the standing waves and differences that small changes in feed-line length can have on results.

To get the best out of a tracking signal gen or a noise source, I think its important to see the results warts and all on a spectrum display rather than just a number on a meter that often where where feed-lines are involved, means nothing.


#10

Thanks for the photo. Once repaired, I may forego the heat sinks and just go with the fan. Hadn’t figured out how I was going to mount heat sinks on those tiny ‘blobs’ anyway. It’s be good to be able to get back to some testing.

yxespotter