This is the reason I suggest just adding a helical to the front end of
the regency, they really don't have evidence of a grat overlap or
overload unless a user has a really wide signal which sounds like it may
be the case. In the beginning I was under the assumption it was the
output making spurs but it apparently is only a few users causing this
rx falsing, if it were me I would invite the spurious user to my machine
and let his spurs cause the other bunch falsing and then he will have
more evidence to use to advise that user - your radio needs a little
help to keep it on frequency. Offer to help him make it better, even
though he thinks it is fine now what is fine now worth when it could be
better, he will have reports from both sides of the fence that he is the
only one making this problem occur - and you may be able to teach him a
bit about nice clean signals going farther acting like ammunition
compared to throwing watermelons out to sea to kill the prize fish.
mch wrote:
>
> Steve Bosshard wrote:
> >
> >> Unless the problem ISN'T two signals occupying the same spectrum, and
> >> it's just a matter of one receiver hearing outside its 'channel'.
> >>
> >> Joe M.
> >
> > 146R325 occupies from 146315 to 146.335
> > 146.310 occupies from 146.300 to 146.320
> >
> > They SHARE 146.315 to 146.320.
>
> Oh Really? If you ASSUME (and you know how I mean that word) that each
> TX HAS to have 20 kHz of bandwidth, I guess so, but that's not
> necessary. Only if you have 5 kHz deviation and a 5 kHz of frequency
> response (or some equivalent combination) will that be true. Most
> radios, including ham radios, tend to have lower response, and many,
> especially if set up correctly, will have less than 5 kHz of deviation.
> In reality, each will have closer to 3 kHz response and 4.5 kHz of
> deviation. That adds up to about 15 kHz of bandwidth, and ZERO
> overlapping. IOW:
>
> 146R325 occupies from 146.3175 to 146.3325
> 146.310 occupies from 146.3025 to 146.3175
>
> They SHARE... NOTHING!
>
> Now, if your RECEIVER is passing 146.315 to 146.335, yes EXPECT
> problems, as your OWN RECEIVER is causing the problem. I tend to think
> that's the problem in this case. Of course, it could be users with TXs
> that are too wide, too.
>
> > The front end will make NO difference. Unless you have a VHF Crystal
> > Filter ahead of the receiver input, and I doubt that would make any
> > difference.
>
> That must be why people with Micors and MASTR IIs have had fewer
> problems except for very strong signals or users without properly set up
> radios. ;-> They must be liars.
>
> > Go narrow band and change IF filters and reduce modulation on BOTH
> > systems, or QSY.
>
> Well, if you're answer is either all or nothing, I guess so. BUT, there
> is such a thing as GRAY areas where it doesn't have to be all of one or
> none of it. Just because a radio CAN do 7 kHz deviation doesn't follow
> that it MUST do 7 kHz deviation. Most people gave that mentality up when
> they left CB. ("Only 100% modulation? Crank it up!!!")
>
> You CAN limit your NFM deviation (modulation) and frequency response to
> get adequate rejection without going overboard to SNFM. Of course, this
> won't matter if your front end is wide as an elephant, which seems to be
> the case here. Even IF you would go to SNFM, if your front end is
> passing the RF energy that's contained in the adjacent channel's
> passband, the problem will still exist.
>
> I bet the Micor solves most of, if not all of the problem. Of course, it
> will have done it via the methods I mentioned above and if the user
> limits it to 4.0 kHz user audio + 0.5 kHz CTCSS deviation. Of course, it
> won't matter how wide his TX is, as it's the RX that has the problem,
> but to be a good neighbor and solve the problem for the users, it should
> be set up this way.
>
> Joe M.
>
--
73...Clark Beckman N8PZD
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