Topband: Slightly OT - amplifier noise

[Mike Waters]

Roger,

I didn't realize that the 1025 (which is what I have) didn't have a preamp
on the auxiliary (noise) antenna input!

I chose the 1025 over the 1026 because I did not want the small whip
antenna, which only works well if you have RFI close to it. If I would have
realized that the 1026 circuit had a preamp, I might have purchased that
instead.

But when I do use it (very rarely), I almost always use a homebrew W7IUV
preamp to feed the noise antenna input, with no issues.

What kind of preamp did you add to your 1025?

73, Mike
W0BTU

On Tue, Mar 17, 2020, 1:18 PM Roger Kennedy <roger at wessexproductions.co.uk>
wrote:

>
> Having just read some of these posts, I just did a few tests on my
> MFJ-1025.
> (bought mine second-hand very cheap - a lot of people buy these thinking
> they will get rid of any noise!)
>
> I modified it to become a 1026 . . . you definitely need the extra pre-amp
> for the "Noise Antenna", especially on 160m - fortunately they use the same
> PCB for both versions, so you can easily add their extra preamp circuit
> design on the PCB.
>
> I normally only use mine on 160m . . . but just did a test on 15m & 10m . .
> . it adds no noticeable noise whatsoever !
>
> So I think the OP's must be faulty . . perhaps powering it by a noisy PSU?
>
> Roger G3YRO
>
>