Pete KE9OA schrieb:

[snip]
The full audio response of those older Grundig receivers has to be heard to
be believed. I gave my Grundig 210, also known as the TR-6001 to my wife.
She still likes to play with it.

Sadly, there aren't too many receivers with good audio and tone controls
out there these days, but I do like my rebranded Redsun RP2000 (Roadstar
TRA-2350P; you may be interested in the "service manual" available
online, looks like an oldschool engineer was at work there). Even when
using headphones, tone controls (particularly for highs) are highly
useful in obtaining maximum AM intelligibility / fidelity. The muffled
audio on my 7600G bothered me for a long time. (This also has another
flaw, fixed with the 7600GR: Somehow some severely undersized audio
coupling caps sneaked in, limiting bass response and degrading audio
quality even further.)

The Grundig Satellit 700 seems to command high prices, but it is relatively
deaf when compared to the older Grundig units.

Supposedly these sets have issues with suboptimum frontend tracking
alignment right from the factory, which would explain the deafness.
(They also have their share of age-related problems now.) Given a
consumer-level 1st mixer, frontend tuning may improve strong signal
handling dramatically - the Redsun frequently shows 2nd order intermod
here especially with its high maximum RF gain (but never 3rd order), and
the AN-LP1 really works wonders with that.

The newer Chinese portables aren't bad..............the limiting factor with
these units is using only a 2-pole roofing filter at the 1st I.F. This gives
a maximum 2nd I.F. rejection ratio in the 45dB range.

That's about right, the Redsun is spec'd with "40 dB". However, my Sony
7600G fares worse than the Redsun here.

You can see the manifestation of this problem when you hear the (2 X 455kHz)
images of the 6MHz band when you tune 910KHz below the 49M band. Since this
is a 2nd I.F. rejection problem, it will occur throughout the whole tuning
range.

In many cases, this even extends to MW/LW (again, e.g. 7600G). The
Redsun thankfully got electronic frontend tracking like you'd see on a
single conversion set, thus the image rejection claim of "60 dB" for MW
seems reasonable. (It's a good rx on this band in any case, even the
wide filter - a 6-pole 12 kHz job - is quite useful. Only the old
ICF-7600A beats it when it comes to background noise on weakish
stations, but that one has a bit worse selectivity and may apparently
inadvertantly catch some shortwave stations at times, as the MW mixer
and SW 2nd mixer outputs are tied together and sharing an IFT.)

An outboard tunable RF preselector will give you better rejection of
this problem.

That, and the intermod. IMO a tunable active loop antenna helps out
"normal" receivers a lot.

I did get to play with Prototype 4 or 5 of the E5 when it first came out.
Too bad they didn't stick with the blue LED backlight for the display. It
looked much nicer than that washed out display that they are using now.

Using blue LEDs for lighting is not a good idea if you're running on
batteries - our eyes are much more sensitive to the light emitting from
less flashy-looking amber and green LEDs, and IIRC those should also
have a higher efficiency.

There is also the Panasonic RF-2200. This is a pretty good receiver, but it
definitely doesn't have the MW performance of some of the better portables.

Interestingly, many people seem to state the contrary, though I have
read hints that there may be better but less well-known sets out there.
The Panasonic's rotating antenna is quite unique and gives some definite
advantages over having to rotate the whole set.

signal. Still, it is nice to have that "Collins" looking tuning dial. It was
a pretty good deal at the original 140 price tag. It also had a great FM
section with super selectivity.

Yup, 3 IF filters in there. With 3 carefully matched modern-day 180 kHz
filters, it would probably make quite a good FM DX machine. (The Redsun
features two 180s, which already give it good selectivity for a
portable. Sony never bothered to put in anything narrower than those
cheap 280 kHz barn doors.)

Oh, and would you mind sending me said SW1 service manual?

Stephan
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