Hi Pete

How can that be? You're saying the circuitry was designed that way? They
couldn't do double for all the bands??

Lucky

"Pete KE9OA" wrote in message
...
I remember that radio..............it was advertised as being dual
conversion above 10MHz, single conversion below.

Pete

"dxAce" wrote in message
...


Stephan Grossklass wrote:

Lucky schrieb:

BTW,

Didn't they know 666 was not the best choice for the US??

Apparently not. But AFAIK the same rig with slighly modernized exterior
was sold as R-300 later.

Why was it not a good choice for the US? Just out of curiosity.

dxAce
Michigan
USA

Yes Yes!

I found a picture of it lit up in the dark. Nice cool green meter display.
All I can say is try to find one of these somewhere. I bet it wouldn't be
easy. I think this radio will entertain me more then then the $81 I hope.
Thanks

Lucky


"John S." wrote in message
ups.com...
Sure...I owned the later version, R300 with the SWL bandspread dial.
They are double conversion on all but the lowest sw and all of the mw
band. Double conversion doesn't help much with the images, which
abound.

Still, it is a fun radio to use and it looks like it should have tubes
inside. The crystal marker allows accurate (by pre-digital standard)
tuning. And it has two filters that actually work, although they are a
bit sloppy for ssb work. After a few hours behind the dial, it does
become a bit tedious and you realize just how far receivers have
improved. It's younger digital siblings, the R600, R1000 and R2000
would be much easier to use and would perform much better. They will
not "look" like a glow-in-the-dark radio however.

If you are in the market, don't pay much over $100.

Lucky wrote:

"Mark S. Holden" wrote in message
...

Lucky wrote:


Does anyone here remember the Kenwood QR-666 or has owned one?
How were they? I can't find out if they were double or triple conversion.

How much do you think they are worth nowadays for collectors?

Thanks
Lucky

The Osterman book says it's double conversion.

The prices in that book are somewhat out of date, but they felt it was a
one star (value rating) radio and worth $60-80.

For comparison, the same book indicated the range for a used R-1000 was
$280-$300 and they gave it 5 stars for value. The R-2000 was $380-$450
and 4 stars.



BTW,

Didn't they know 666 was not the best choice for the US??

Lucky



Are you saying Profit Stare wouldn't be likely to promote it?

"Lucky" ) writes:
Hi Pete

How can that be? You're saying the circuitry was designed that way? They
couldn't do double for all the bands??

Lucky

I'm curious about how it was done, but it was not uncommon to have
receivers in the old days that switched to double conversion only
on the highest band(s).

Back then, the normal IF was 455KHz, this was before crystal filters
in the HF range became available (and once they did, before they became
common). It was pretty easy to have good image rejection at the lower
bands with that IF frequency, and given that one did have front
end tuning tracking the local oscillator, there was little incentive
to do things differently.

But at the higher bands, 10MHz and up (the exact frequency being
more determined by how the receiver breaks the 3 to 30MHz range into
bands), image rejection became more of a problem. On the really
cheap receivers, it pretty much disappeared, as you'd often see
in reviews of such receivers. A receiver like the National HRO series
had two stages of amplification before the mixer, and the extra tuned
circuits apparently helped to keep out images.

So double conversion was added on the highest band(s). A stage of
a combined mixer/oscillator was added one those bands, or more
commonly there was a stage of 455KHz amplification that was
turned into a mixer/oscillator on the highest band(s). The first
IF would then be in the 2MHz or so range, and that extra stage
would drop it down to 455KHz. This counted on having enough selectivity
at the first IF so the 455KHz images were knocked down enough.
The Hammarlund SP-600 did this (and benefitted especially since it
tuned right up to 54MHz), and a Heathkit portable comes to mind too.

Why not make it double conversion through all the tuning ranges?
Maybe because the extra conversion always adds problems, so if
you only have it in place when actually needed, you cut down
on unwanted spurs. Double conversion gives two chances for
images, and a mixer is more prone to overload than an amplifier,
so if you don't need the extra conversion for image rejection,
the extra conversion is a liability.

The other common scheme for double conversion back then was to
have a receiver that tuned a fixed range, and then toss in a
crystal controlled converter ahead of it to add the extra bands.
In some cases, you had single conversion on one band, because
the fixed tuning range would be a useable part of the spectrum.
A classic example would be a receiver that tunes the 80meter
ham band, 3.5 to 4MHz. For that band it would be single conversion.
But to tune the higher bands it would be double conversion, with
the bands converted first to that 3.5 to 4MHz range. Receivers like
this had the advantage that since the tuning was for only one range,
it was worth making a good linear oscillator and a good dial. Which
is where receivers like the Collins R388 came from.

Double conversion became a different thing once crystal filters in
the HF and even VHF range came along. Up conversion was then happening
and that has certain advantages. Once the first IF has a decent
filter, you will get good image rejection for the second IF, and
since you have a relatively narrow bandwidth at that first IF,
overload of the second mixer becomes more difficult, since it's
only seeing a small portion of the spectrum. And then LC oscillators
became synthesized to a crystal reference, and it no longer mattered
where the oscillator tuned.

Michael

"Michael Black" wrote in message
...

"Lucky" ) writes:
Hi Pete

How can that be? You're saying the circuitry was designed that way? They
couldn't do double for all the bands??

Lucky

snip

Why not make it double conversion through all the tuning ranges?
Maybe because the extra conversion always adds problems, so if
you only have it in place when actually needed, you cut down
on unwanted spurs. Double conversion gives two chances for
images, and a mixer is more prone to overload than an amplifier,
so if you don't need the extra conversion for image rejection,
the extra conversion is a liability

Michael

That makes perfect sense. But, if they did it right the first time, there
would not be any added problems. Back in 1970-75, they were still in the
dark ages of radio

Thanks
Lucky

"Mark S. Holden" wrote in message
...
Lucky wrote:

"Mark S. Holden" wrote in message
...

Lucky wrote:


Does anyone here remember the Kenwood QR-666 or has owned one?
How were they? I can't find out if they were double or triple
conversion.

How much do you think they are worth nowadays for collectors?

Thanks
Lucky

The Osterman book says it's double conversion.

The prices in that book are somewhat out of date, but they felt it was a
one star (value rating) radio and worth $60-80.

For comparison, the same book indicated the range for a used R-1000 was
$280-$300 and they gave it 5 stars for value. The R-2000 was $380-$450
and 4 stars.



BTW,

Didn't they know 666 was not the best choice for the US??

Lucky

Are you saying Profit Stare wouldn't be likely to promote it?


Well,

I listen to him sometimes. Let's see how good the "666" radio brings him in.
Perhaps this radio let's you hear only what a person is really thinking. It
only broadcasts the truth. Now I'm kind of scared about it myself. The
headline for this radio in the ad only said "Kenwood Shortwave Radio"

If you didn't check the listing manually, you wouldn't find it. It didn't
say "QR-666"
or "Pre R-300" I wonder what the black box brings??

Lucky

The both the 666 and R300 show up on Ebay periodically. To make room
for new acquisitions the R300 had to move on to other users.

I owned one for about a year and enjoyed it for what it was. If you
have never owned a band spread receiver with a crystal marker for dial
alignment, then you are in for what I would call both a treat and a
challenge. It is fun to learn something different, even if it is not
new.

The bandswitch can be problematic on those radios. Mine required
periodic cleaning and precise positioning to function on the lowest
shortwave band. A Kenwood technician told me that switch was a
potential source of problems and that there were no replacements.
Have fun, and be sure to post your impressions after you've played with
it a while.

Lucky wrote:

I'm so glad to hear you're doing OK. I was a little worried about you for a
while chap. I didn't see any posts from you like before and wondered what
happened.


I posted a reply to your inquiry about me around Noon on Friday.

Regards,

Mark

dxAce wrote:

"Michael A. Terrell" wrote:

666 = a reference from the bible.

OK, but then most of the world uses Arabic numerals, so why would 666 merely
apply to the US?


You have me there. Maybe the comment was made as a joke?

--
Former professional electron wrangler.

Michael A. Terrell
Central Florida

"Michael A. Terrell" wrote:

dxAce wrote:

"Michael A. Terrell" wrote:

666 = a reference from the bible.

OK, but then most of the world uses Arabic numerals, so why would 666 merely
apply to the US?

You have me there. Maybe the comment was made as a joke?

Perhaps it was.

By the way, finally hit 70 here this afternoon. A beautiful day. About ready to go
over to the neighbours and smoke a celebratory Cuban cigar with him.

dxAce
Michigan
USA