RadioBanter - View Single Post - s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.

Telamon · January 6th 07, 09:37 PM posted to rec.radio.shortwave

In article ,
BDK wrote:

In article telamon_spamshield-C9BF19.20290005012007
@newsclstr03.news.prodigy.net,
lid says...
In article ,
BDK wrote:

In article telamon_spamshield-F6523C.20501704012007
@newsclstr02.news.prodigy.com,
lid says...
In article ,
BDK wrote:

In article m,
says...

David wrote:
On Fri, 05 Jan 2007 02:17:32 GMT, Telamon
wrote:

In article
s.com,
"john" wrote:

An exception would be radios that have a signal strength meter
in
dBm,
which is an absolute scale.

Millivolts?

actually the palstar and the drake scales are in Decibels, while
the
kenwoods scale is in Db at the top and millivolts at the bottom.
also
before anyone asks my rf gain is fully clockwise on both the drake
and
kenwood. the palstar doesn't have a rf gain control.

You can't even be sure identical radios will have the same S-Meter
readings, in most cases. The reading is pretty meaningless, except to
compare antennas, or if a preselector is used, to adjust for max
reading.

Nonsense.

Wanna bet? In most cases, side by side, identical models have different
meter readings. Usually it's slight, but sometimes it's huge. My JRC
NRD-515 has a "tight" meter. SSB audio can be clearly heard with the
meter at the left peg. Another 515 I had here for interconnect repair
was just as sensitive as mine, but the same signal would read S-2 or 3.
Same thing has happened with Kenwood R5000's, R2000's, and JRC NRD-525s.
(The first ones had a "spastic" S-Meter, later ones were cured of this)

In "pro" radios it might be true, but in hobby receivers, it's not true
that S-meters have any real correlation with signal strength in
comparing one radio to another.

Oh come on. The same model with the same factory adjustment would have
the same reading or very close. It would be reasonable to see a small
variation but a "huge" difference would indicate a problem with one of
the radios.

Obviously, your and my idea of "tolerances" isn't what theirs is. A
whole lot of radios are aligned "just good enough", or they need
touching up due to aging after a really short time. Some just are not
right at all out of the box, and a slight adjustment works wonders. I've
seen huge differences between Icom R-71A's. Some, like the last one I
had were dead on freq, the PBT was aligned right, etc, but some I had
previously owned, and worked on weren't even close. Some of these were
brand new, and I was helping the owner install a filter or something.
when compared to a good one, it was obvious something was wrong.

Electronic Equipment Bank (EEB) sold a lot of alignments on brand new
radios, as the factories weren't doing a real good job of it. They would
turn on your brand new R71A, R5000, Yaesu FRG-8800, and let it cook for
a couple days, then align it.

Then there is the thing all the major brands of ham and SW equipment
have in common, the lack of ability to tighten screws. Most were just
snugged, and by the time the thing had ridden across the country in a
UPS or Fedex truck, gone through a few heat/cool cycles in the process,
they weren't even close to being tight anymore. Even after an EEB
alignment, the S-Meter's could still be off a little from one to the
next.

Then you have techs who forget to tighten screws in your $1000 receiver
before they ship it, and not only does the alignment get messed up, but
you are overjoyed that something wasn't broken. Yes, it happened to me
about 15 years ago. I sent my NRD-515 in for a minor problem, more an
annoyance than anything else. When it came back, it rattled, and two
screws holding the top PC board had fallen out, and the rest were so
loose they were about to fall out. I ended up checking around and
finding a good freq counter and realigned it myself. Close, but not 100%
right, I need to do it again. I also fixed the original problem that
they "couldn't duplicate". Odd, since it did it as soon as I turned it
on after I put the screws back in and tightened it all up.

The only real way to compare (without any equipment) two radios is to
hook them up to a coax switch and then to the same antenna, and switch
them back and forth to compare.

Sure there are many reasons a radio may not perform to specifications.

Specifications can only get you so far. You do have to actually operate
the radio to find out if its total performance is in line with your
expectations.

--
Telamon
Ventura, California