In article ,
gareth wrote:
Path: eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: "gareth"
Newsgroups: rec.radio.amateur.boatanchors,uk.radio.amateur
Subject: Variable selectivity?
Date: Sun, 13 Oct 2013 19:11:43 +0100
Organization: A noiseless patient Spider
Lines: 62
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Further information most welcome, thank-you

In the 1948 Radio handbook which I mentioned previously, there are adverts
from a company by the name of Millen, and I assumed it was the same guy
after he had left National.

I'm a bit surprised to see any doubt about James Millen as the honcho
of National Company before 1939, his departure from National, and his
setting up James Millen Manufacturing in Malden, Mass. a short
distance from National in 1939-40. Yes, there was only one James
Millen. There are a couple of web sites devoted to (Jim) Millen's
history. I worked for James Millen Mfg. for a couple of years in the
1950's, so know a bit about Millen and some of the history behind the
1939 split with National. It was never entirely clear to me just
what went on---on the one hand, a desire on the part of National's
principal money backers to go public, and to move the company in
different directions, with more consumer products; also, some
financial things that reduced the money that Millen and his close
associates (most or all of whom moved to Millen Mfg.) got from
National.

Your comment about a phenolic intersperser is no doubt some means of
isolating an
earthy contact?

I don't know about Hammarlund's variable coupling IF's in any detail,
but I'd suspect that the interposition of a phenolic piece was for
mechanical reasons, not electrical. Millen offered a line of IF
transformers (455 and 1600 Khz) that used adjustable capacitive coupling
only between the coils---one of my projects when I worked there.

It would be interesting to know from the Lamb patent whether he proposed
therein the
technique of Single Signal Reception by the use of the phasing control to
null
out the audio image, or whether this was something that came about through
experience?

So far as I know, Lamb's single signal focus was on CW reception with no
audio content. As I recall, phasing the crystal filter came later.
Early (1933-34) production receivers I know of that used Lamb's
principles were the National AGS-X and FB-7X; and the RME-9D.

Hank

In article ,
Richard Knoppow wrote:

James Millen was one of the founders of National but
eventually was pushed out of the company. He started his own
company, also in Malden Mass, and probably made many parts
for National as well as his own stuff. Millen made very high
quality components.

Millen Mfg., at least at the time I worked there, was in direct
competition with National Co. on several products, and neither
company supplied the other.

The National HRO was a revolutionary receiver in its day
and stayed one of the favorites for both ham and commercial
use for some thirty years. The mechanical design is
attributed mostly to James Millen and the electronic design
mostly to Herbert Hoover Jr., son of the president of the
US.

While the HRO was a legendary product, I'd hardly call it
"revolutionary." It was a follow-on to the AGS line, with objectives
to maintain AGS performance at lower cost-to-manufacture, and to
normalize the coil-set interface so that the tuning coils could be
built all-in-one-box and interchangeable. An examination of the
schematic will show it to be essentially a copy of higher-end home
entertainment circuits of the era, with a crystal filter and bfo
added. Much of the actual performance came from use of better coils
(house-built) in the RF and IF stages, a house-built tuning capacitor,
and the house-built tuning dial was superior to almost anything else
around. In short, a relatively straightforward tried-and-proven
electrical design, but extremely well-executed in component quality
and mechanical structure, pretty much hallmarks of Jim Millen's team.

Worth noting that the NC-100, National's follow-on product, had
similar performance, with the advantage of having internally-mounted
and switchable tuning coils.

Hank

"Hank" wrote in message
...
In article
,
Richard Knoppow wrote:

James Millen was one of the founders of National but
eventually was pushed out of the company. He started his
own
company, also in Malden Mass, and probably made many parts
for National as well as his own stuff. Millen made very
high
quality components.

Millen Mfg., at least at the time I worked there, was in
direct
competition with National Co. on several products, and
neither
company supplied the other.

The National HRO was a revolutionary receiver in its
day
and stayed one of the favorites for both ham and
commercial
use for some thirty years. The mechanical design is
attributed mostly to James Millen and the electronic
design
mostly to Herbert Hoover Jr., son of the president of the
US.

While the HRO was a legendary product, I'd hardly call it
"revolutionary." It was a follow-on to the AGS line, with
objectives
to maintain AGS performance at lower cost-to-manufacture,
and to
normalize the coil-set interface so that the tuning coils
could be
built all-in-one-box and interchangeable. An examination
of the
schematic will show it to be essentially a copy of
higher-end home
entertainment circuits of the era, with a crystal filter
and bfo
added. Much of the actual performance came from use of
better coils
(house-built) in the RF and IF stages, a house-built
tuning capacitor,
and the house-built tuning dial was superior to almost
anything else
around. In short, a relatively straightforward
tried-and-proven
electrical design, but extremely well-executed in
component quality
and mechanical structure, pretty much hallmarks of Jim
Millen's team.

Worth noting that the NC-100, National's follow-on
product, had
similar performance, with the advantage of having
internally-mounted
and switchable tuning coils.

Hank

While the HRO had similar circuits to home receivers of
the time I rather think there was not that much variation
available. The HRO did use pentode mixers in place of
hexode or pentagrid mixers resulting in low noise. The
NC-100 was certainly a clever design but had only one RF so
its image rejection is not as good as the HRO.
I forgot to mention Dana Bacon another designer at
National. I am not sure what contributions he made.


--

--
Richard Knoppow
Los Angeles
WB6KBL

On Sun, 13 Oct 2013, gareth wrote:

Further information most welcome, thank-you

In the 1948 Radio handbook which I mentioned previously, there are adverts
from a company by the name of Millen, and I assumed it was the same guy
after he had left National.

Your comment about a phenolic intersperser is no doubt some means of
isolating an
earthy contact?

It would be interesting to know from the Lamb patent whether he proposed
therein the
technique of Single Signal Reception by the use of the phasing control to
null
out the audio image, or whether this was something that came about through
experience?


ONce again, "single signal selectivity" is credited to the Lamb filter,
everyone referencs that famous QST article of his. You don't need the
phasing control to get the single signal selectivity.

Micahel VE2BVW

On Sun, 13 Oct 2013, Richard Knoppow wrote:


"gareth" wrote in message
...
Further information most welcome, thank-you

In the 1948 Radio handbook which I mentioned previously,
there are adverts
from a company by the name of Millen, and I assumed it was
the same guy
after he had left National.

Your comment about a phenolic intersperser is no doubt
some means of isolating an
earthy contact?

It would be interesting to know from the Lamb patent
whether he proposed therein the
technique of Single Signal Reception by the use of the
phasing control to null
out the audio image, or whether this was something that
came about through experience?


I think this was part of Lamb's original intention. The
articles originally describing the use of the filter were
aimed at "single signal" reception, meaning that the audio
image was suppressed. The Lamb filter required some juggling
between the bandwidth and phasing adjustments to get the
response to where the operator wanted it since they
interacted with each other and with the center frequency.
Nonetheless, the filter worked very well and provided an
order of magnitude better selectivity than was available
previously.
James Millen was one of the founders of National but
eventually was pushed out of the company. He started his own
company, also in Malden Mass, and probably made many parts
for National as well as his own stuff. Millen made very high
quality components. There is considerable history of both
National and Millen, including a Millen Society, on the web,
a Google search will find it.
The National HRO was a revolutionary receiver in its day
and stayed one of the favorites for both ham and commercial
use for some thirty years. The mechanical design is
attributed mostly to James Millen and the electronic design
mostly to Herbert Hoover Jr., son of the president of the
US.

And Hoover Jr. was president of the ARRL for a while.

Michael VE2BVW

On Mon, 14 Oct 2013, Hank wrote:

In article ,
gareth wrote:
Path: eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: "gareth"
Newsgroups: rec.radio.amateur.boatanchors,uk.radio.amateur
Subject: Variable selectivity?
Date: Sun, 13 Oct 2013 19:11:43 +0100
Organization: A noiseless patient Spider
Lines: 62
Message-ID:
References:
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Further information most welcome, thank-you

In the 1948 Radio handbook which I mentioned previously, there are adverts
from a company by the name of Millen, and I assumed it was the same guy
after he had left National.

I'm a bit surprised to see any doubt about James Millen as the honcho
of National Company before 1939, his departure from National, and his
setting up James Millen Manufacturing in Malden, Mass. a short
distance from National in 1939-40. Yes, there was only one James
Millen. There are a couple of web sites devoted to (Jim) Millen's
history. I worked for James Millen Mfg. for a couple of years in the
1950's, so know a bit about Millen and some of the history behind the
1939 split with National. It was never entirely clear to me just
what went on---on the one hand, a desire on the part of National's
principal money backers to go public, and to move the company in
different directions, with more consumer products; also, some
financial things that reduced the money that Millen and his close
associates (most or all of whom moved to Millen Mfg.) got from
National.

Millen was such a strong name by itself (I remember the single column ads
in the back of QST in 1971 when I started reading it), I think it was only
in recent years that I learned he had been part of National. That there
was a connection between the two companies had always seemed obvious,
though I assumed Millen had been like a subcontractor to supply parts to
Natinoal.

Millen probably was better off as a separate company, he could "design for
excellence" and have his name more prominent.

MIchael VE2BVW

On Mon, 14 Oct 2013, Richard Knoppow wrote:


"Hank" wrote in message
...
In article
,
Richard Knoppow wrote:

James Millen was one of the founders of National but
eventually was pushed out of the company. He started his
own
company, also in Malden Mass, and probably made many parts
for National as well as his own stuff. Millen made very
high
quality components.

Millen Mfg., at least at the time I worked there, was in
direct
competition with National Co. on several products, and
neither
company supplied the other.

The National HRO was a revolutionary receiver in its
day
and stayed one of the favorites for both ham and
commercial
use for some thirty years. The mechanical design is
attributed mostly to James Millen and the electronic
design
mostly to Herbert Hoover Jr., son of the president of the
US.

While the HRO was a legendary product, I'd hardly call it
"revolutionary." It was a follow-on to the AGS line, with
objectives
to maintain AGS performance at lower cost-to-manufacture,
and to
normalize the coil-set interface so that the tuning coils
could be
built all-in-one-box and interchangeable. An examination
of the
schematic will show it to be essentially a copy of
higher-end home
entertainment circuits of the era, with a crystal filter
and bfo
added. Much of the actual performance came from use of
better coils
(house-built) in the RF and IF stages, a house-built
tuning capacitor,
and the house-built tuning dial was superior to almost
anything else
around. In short, a relatively straightforward
tried-and-proven
electrical design, but extremely well-executed in
component quality
and mechanical structure, pretty much hallmarks of Jim
Millen's team.

Worth noting that the NC-100, National's follow-on
product, had
similar performance, with the advantage of having
internally-mounted
and switchable tuning coils.

Hank

While the HRO had similar circuits to home receivers of
the time I rather think there was not that much variation
available. The HRO did use pentode mixers in place of
hexode or pentagrid mixers resulting in low noise. The
NC-100 was certainly a clever design but had only one RF so
its image rejection is not as good as the HRO.

And that the HRO had two RF stages seems to be a significant factor.

Even in the seventies, when Ray Moore wrote a number of articles about
receiver design in Ham Radio magazine, he pointed out that one reason the
HRO stood out was the 2 rf stages, which mean much better image rejection
than the average receiver. The HRO-60 (or was it the 50?) added double
conversion on the higher bands, but the earlier models were still
contenders in that period for good image rejection on the higher bands.
And of course, the design was good, so the extra stage actually helped
rather than hindered.

A superhet is a superhet, it's small details like this that made some
better than others.

A couple of years ago, I found at a garage sale for 2.00 a Grundig/Eton
pocket shortwave receiver. It's a pretty crummy receiver, but without
adding cost to it, they included a frequency counter. So a receiver
probably as bad and as simple as my Hallicrafters S-120A from 1971
instantly gets a giant improvement in tuning because of that frequency
counter. And once they did away with the analog dial, they could break
the tuning segments up into smaller ranges, helping the tuning process.

What initially complicates the receiver tremendously (or would if the
frequency counter wasn't a single IC that also included a clock function
and cost very little and took up little space), actually simplifies it.

Today, you can stick with a 455KHz IF and then fuss over image rejection,
or you can move to a higher IF and simplify the front end. Or go with
double conversion, getting the easier image rejection, yet selectivity
down where you can do things like use LC circuits.

A single conversion receiver with 455KHz and one RF stage (if that) can't
be much different from a circa 1930s receiver, communication or consumer,
but you can now make simple receivers with other methods that actually
mean better performance.

It amazes me that over the past 7 years or so I've found shortwave
receivers at rummage and garage sales, all nice and cheap, that are so
much better than that 1971 Hallicrafters. Or even buy a new digitally
tuned portable receiver for about the price I paid in 1971 for that
Hallicrafters, and get nearly infinitely better capability.

Michael VE2BVW

"Michael Black" wrote in message
xample.org...
On Sun, 13 Oct 2013, gareth wrote:
Further information most welcome, thank-you
In the 1948 Radio handbook which I mentioned previously, there are
adverts
from a company by the name of Millen, and I assumed it was the same guy
after he had left National.
Your comment about a phenolic intersperser is no doubt some means of
isolating an
earthy contact?
It would be interesting to know from the Lamb patent whether he proposed
therein the
technique of Single Signal Reception by the use of the phasing control to
null
out the audio image, or whether this was something that came about
through
experience?
ONce again, "single signal selectivity" is credited to the Lamb filter,
everyone referencs that famous QST article of his. You don't need the
phasing control to get the single signal selectivity.

Incorrect.

If the Xtal alone gave you single signal reception, then there'd be no
advantage
whatsoever in having the phasing control.

That the phasing control can be used to null out other signals is the strong
indication
that more than the one signal is getting through the Xtal.

Single Signal reception is the reference to the audio image being phased
out.

On 14/10/2013 20:26, gareth wrote:

That the phasing control can be used to null out other signals is the strong
indication
that more than the one signal is getting through the Xtal.

Surely the phasing control is there to allow the operator to introduce
an antiphase of the unwanted signal(s) leaking *around* the crystal?

"gareth" wrote in message
...
Incorrect.

If the Xtal alone gave you single signal reception, then there'd be no
advantage whatsoever in having the phasing control.

That the phasing control can be used to null out other signals is the
strong indication that more than the one signal is getting through the
Xtal.

Single Signal reception is the reference to the audio image being phased
out.

Let's go Beanie, let's go.