Pete KE9OA wrote:
I want to come up
with a design that tracks the signal all the way down into the noise. I
think that a big part of it will be having a long enough time constant on
the loop filter, so that if a signal fades out, there is enough hysteresis
to "hang on". The tradoff is acquistion time of the system, but I think that
I will be able to find a happy medium.

Ah, you addressed my concern already. I think slow
acquisition time may be entirely acceptable. Question:
would the receiver be mute prior to achieving phase lock, or
would there be some audio recovery as you wait for it to get
an initial phase lock?

On Mon, 20 Oct 2003 20:52:46 -0500, Friendly Everyday Mad Scientist wrote
(in message ):

Agreed -- I'd never miss an envelope detector if I had a
good Sync. detector, but this is clearly ASSUMING the sync.
detector circuit degrades gracefully as it loses lock on
extremely weak signals. If it's going to pop rapidly in and
out of sync. in response to fast & deep fading instead, I'd
argue that would be a huge complaint area. The original
Drake R8 had OK sync., but it really couldn't handle signals
that faded below its ability to maintain phase lock. Same
with my Sony 7600G. I turn off sync. for very weak signals
to avoid the PLL sweeping around and making squeals and
other annoying noises as lock is acquired and lost rapidly.

Just a thought.

--------------------------------------------------------

Hi Ross (& y'all) - This might get back to my advocacy of interchangeable
sub-chassises (---might not be a word).

Under the philosophy of it's easier to buy four $200 radios than it is to buy
one $800 radio, it might be "interesting" grin to have a "basic radio" -
nice but not the best thing in the world.

But: have every separate section ("module") pluggable (---might not be a
word, either) and replaceable by at least one "very, very nice/good" module
of the highest possible quality (and, perhaps, by more than one other at
different prices and at different levels and, again perhaps, with different
features for different wants and desires).

Or sumthin'.


Just thunk of: and could - possibly - publish specs and encourage third party
sub-chassises (---still might not be a word).


Gray Shockley
--------------------------------------------------------
Who was - quite obviously - traumatized by
an AN/TRC-24 during his impressionable years.

Friendly Everyday Mad Scientist wrote in message ...
2. Still using DDS for the LO? Make sure the encoder knob "feels" like a
good old variable capacitor (or variable inductor). I have been
universally disappointed by the shaft encoders used on current
synthesized radios.

US Digital has a line of optical encoders that spin freely
and with no hint of inbalance or friction, let alone actual
detents.

I just checked out their web site. Their encoders seem heavily biased
towards the industrial positioner market, and I see how friction is
very undesirable there. But some of their lower end ones look very
amenable to putting a knob on (preferably a nice big heavy knob with a
spinner...)

But friction on the tuning knob isn't necessarily a bad thing... a certain
amount of friction is a good thing, and I think most of the better government-
aimed receivers even have adjustable knob tension.

One thing I don't miss at all about the "good old days" is backlash in
the tuning mechanism! Here direct-drive optical encoders are a clear
winner.

I played with one and was as impressed by its performance as
I was shocked by its price. Then again, $50 for an
optical encoder that lasts forever is probably a lot better
than $25 for one that feels "clicky" and mechanically wears
out after a short time, especially in the "Craft" end of
production volumes.

I wore out a few TenTec PTO's in my younger days - not all the
"old" VFO's were mechanically robust either. And a lot of Heathkit
equipment used a shaft reducer that seemed to depend on some kind of
vaseline-like grease for operation.

The prices on the US Digital encoders do seem very good.

I still am rather annoyed at Drake for putting such a
lousy encoder on the R8B. For that kind of money, I'd
expect something with a lot better longevity and feel. I'd
have gladly paid an extra $50 for the radio for the
"optical" option, if Drake had offered it. I bet a lot of
you would too, given how much better they work.

I don't like detents at all either. I want it to feel like good old
VFO.

Tim.

(Tim Shoppa) wrote:


But friction on the tuning knob isn't necessarily a bad thing... a certain
amount of friction is a good thing, and I think most of the better government-
aimed receivers even have adjustable knob tension.

Ten-Tec receivers as well as the ICOM R-75 and R-8500 have adjustable
tension. My favorite is the '8500. The '75 is a close second, with
an identical knob and similar adjustment.

One thing I don't miss at all about the "good old days" is backlash in
the tuning mechanism! Here direct-drive optical encoders are a clear
winner.

Absolutely!

--
Eric F. Richards,
"This book reads like a headache on paper."
http://www.cnn.com/2001/CAREER/readi...one/index.html

Of course, in the good old days, split gears in the tuning mechanism eliminated
backlash and permitted true continuous, precise tuning.

Bill, K5BY

Friendly Everyday Mad Scientist wrote:
snipped

I still am rather annoyed at Drake for putting such a
lousy encoder on the R8B. For that kind of money, I'd
expect something with a lot better longevity and feel. I'd
have gladly paid an extra $50 for the radio for the
"optical" option, if Drake had offered it. I bet a lot of
you would too, given how much better they work.

-- Ross

Drake did use an optical encoder in the original R8. They stopped using
it because, according to them, it had problems. I've found that
disassembling the rotary encoder, cleaning it with DeOxIt and relubing
it with a synthetic grease like 'Superlube' has solved the intermittent
problems that occur with age. Perhaps the factory lubricant doesn't
react well with the encoder contacts.


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Friendly Everyday Mad Scientist wrote:
snipped

The original Drake R8 had OK sync., but it really couldn't handle signals
that faded below its ability to maintain phase lock. Same with my Sony 7600G. I turn off sync. for very weak signals to avoid the PLL sweeping around and making squeals and other annoying noises as lock is acquired and lost rapidly.

I tried the original R8 when it first came out and didn't like the sync'
detector either. As you said, it lost lock on weak signals and made
annoying sounds. I returned it and waited for about eight more years
until Drake got the sync' right with the R8B. Actually, it was the
revised SW8 that had the good sync' first. Sometimes you have to be
patient in this hobby. :-)


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Pete KE9OA wrote:

Hey Ross, you should see what that MC13030 device works
like..................it it were still in production, this would be my first
choice. I have a picture of the radio that uses this device on the front
page of my website. It is the best device of its kind that I have ever seen,
with in IP3 of +20dBm. Whenever somebody visits my place, and hears the way
the receiver works, they aske my "how much do you want for it?"

Pete

Any chance of getting a clone of the MC13030 for your MW project?


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I just checked on that today.................Motorola never came out with a
replacement, so the Philips TEA6810V looks like the best bet. I will be
picking up the AD607 eval board tomorrow, so it should be interesting.
I just built up a prototype of the shielded loopstick antenna today, and it
seems to be working well. I will be adding a bandpass filter/impedance
matching network later on in the morning.

Pete

starman wrote in message
...
Pete KE9OA wrote:

Hey Ross, you should see what that MC13030 device works
like..................it it were still in production, this would be my
first
choice. I have a picture of the radio that uses this device on the front
page of my website. It is the best device of its kind that I have ever
seen,
with in IP3 of +20dBm. Whenever somebody visits my place, and hears the
way
the receiver works, they aske my "how much do you want for it?"

Pete

Any chance of getting a clone of the MC13030 for your MW project?


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