Hey Jim... Put the rig on ten meters. Take the top cover off; find
the IF gain pot (top board); mark the present position; then turn it
clockwise a bit until the noise increases perceptibly. If you feel
better about the noise, leave the pot there and check out the
performance. If you don't like it, return the pot to it's original
position.
You probably will have to use the ATT on 160/80/40, but performance
will be better on the higher bands.
I had a Jupe for some four years, and always thought there wasn't
enough gain in the RF->IF chain to engage the AGC on a not so strong
signal on the higher bands, so I left the pot advanced a bit.
The original setting had so little gain on ten that I had to crank the
AF gain up quite high to comfortably hear a weak one. Then, of course,
a strong one blows you out of your chair -- A sure sign that there's
not enough gain to make the agc work properly on the higher bands.
You can call the receiver quiet if you like; some folks think it's a
feature, but I think it's a design problem. This was discussed to
death on the Yahoo Jupiter group and a bit on this group. If you
search the archives of either group you will be entertained if not
informed.
You'll also find the the attenuator is about 20db's worth. A bit too
much to return the low bands to their original S meter state, but it's
OK. It really could have used a step 10/20db db attenuator. I remember
looking at the ATT circuit on the schematic, and it was a active
rather than passive. I would have liked to have modified it for 10db
of attenuation, but being old and stupid, I couldn't figure out how to
do that.
Good luck with the Jupe.
Jerome - va7vv
On Fri, 30 Jan 2009 04:47:34 -0800, <jimimaxi2@comcast.net> wrote:
> Thanks for all the responses.
> I use the RF gain at 75% most of the time.
> The "sssssshhhhh" sound in the background of any signal, whether I
> am listening to a transmission or an empty frequency drops
> considerably when the attenuator is applied on the Jupiter.
> I guess what I am talking about is that on the Kenwood and Yaesu I
> hear that same "sssssshhhhh" sound with all attempts to quiet it
> failing.
> I don't hear the sound on the Jupiter without any buttons engaged.
> Why?
> Better radio or I don't know how to eliminate it on the other two
> radios?
>
> THanks,
> Jim C
> KC2ROF
>
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