FM One tube transmitter
 

"Phil Nelson" wrote in message
...
Despite the rather senseless carping (c'mon boys, cut the crap!), this is
cool! Thanks for posting it!

I agree. An interesting post. And now for my usual dumb questions :-)

1. Have you built one (or more) and if so, could we see a photo?

2. What do you mean by "star grounding technique?"

Phil Nelson


Star grounding is a VHF/UHF grounding technique. VHF and higher have to
have VERY short lead dress, including grounding. Star grounding is basically
taking the grounds from each pin that requires a ground or a bypass to the
closest point possible on the chassis. This makes the socket and
grounds/bypasses resemble a star.

FM One tube transmitter
 

Uncle Peter wrote:
Nicely done. I like the dual varactor arrangement, which should have
a lot of advantages over a single diode. All in all, simple and
elegant!

Pete


If I'm reading correctly, the "varactor" is a pair of plain old
rectifier diodes! I never would have thought of using power diodes for
this application. I guess I thought there would have been way too much
capacitance to be able to reasonably resonate them at 100 MHz. Good stuff!

Bill

FM One tube transmitter
 

If I'm reading correctly, the "varactor" is a pair of plain old
rectifier diodes! I never would have thought of using power
diodes for this application. I guess I thought there would
have been way too much capacitance to be able to reasonably
resonate them at 100 MHz. Good stuff!

About 45 years ago, Popular Electronics had a construction project for an
FM-band transmitter. It used a reverse-biased silicon rectifier to modulate
the carrier.

I assume two back-to-back diodes increases the linearity of the modulation.

FM One tube transmitter
 

On Sun, 8 Jul 2007 16:18:15 +0900, "Brenda Ann"
wrote:


"Phil Nelson" wrote in message
m...
Despite the rather senseless carping (c'mon boys, cut the crap!), this is
cool! Thanks for posting it!

I agree. An interesting post. And now for my usual dumb questions :-)

1. Have you built one (or more) and if so, could we see a photo?

2. What do you mean by "star grounding technique?"

Phil Nelson


Star grounding is a VHF/UHF grounding technique. VHF and higher have to
have VERY short lead dress, including grounding. Star grounding is basically
taking the grounds from each pin that requires a ground or a bypass to the
closest point possible on the chassis. This makes the socket and
grounds/bypasses resemble a star.


At the audio manufacturer where I worked, star grounding meant to take
all grounds to a single point on the chassis, thus having ground wires
radiate like the points on a star. This avoided ground currents
flowing through the chassis.
Brian McAllister

Sarasota, Florida

email bkm at oldtech dot net

FM One tube transmitter
 

"Brian McAllister" wrote in message
...
On Sun, 8 Jul 2007 16:18:15 +0900, "Brenda Ann"
wrote:


"Phil Nelson" wrote in message
om...
Despite the rather senseless carping (c'mon boys, cut the crap!), this
is
cool! Thanks for posting it!

I agree. An interesting post. And now for my usual dumb questions :-)

1. Have you built one (or more) and if so, could we see a photo?

2. What do you mean by "star grounding technique?"

Phil Nelson


Star grounding is a VHF/UHF grounding technique. VHF and higher have to
have VERY short lead dress, including grounding. Star grounding is
basically
taking the grounds from each pin that requires a ground or a bypass to the
closest point possible on the chassis. This makes the socket and
grounds/bypasses resemble a star.


At the audio manufacturer where I worked, star grounding meant to take
all grounds to a single point on the chassis, thus having ground wires
radiate like the points on a star. This avoided ground currents
flowing through the chassis.
Brian McAllister


That's interesting, and makes sense for audio certainly, but would not be
feasible at 100 MHz, as it would create lead lengths that would be a
significant inductance at that frequency.

FM One tube transmitter
 

Brian is using the term correctly, but Star grounds are not used in RF
equipment.
See link below. The shortest path to ground should be used.

http://www.maxim-ic.com/glossary/ind...Tm/Star_Ground
--
Tom Mills

"Brian McAllister" wrote in message
...
On Sun, 8 Jul 2007 16:18:15 +0900, "Brenda Ann"
wrote:


"Phil Nelson" wrote in message
om...
Despite the rather senseless carping (c'mon boys, cut the crap!), this
is
cool! Thanks for posting it!

I agree. An interesting post. And now for my usual dumb questions :-)

1. Have you built one (or more) and if so, could we see a photo?

2. What do you mean by "star grounding technique?"

Phil Nelson


Star grounding is a VHF/UHF grounding technique. VHF and higher have to
have VERY short lead dress, including grounding. Star grounding is
basically
taking the grounds from each pin that requires a ground or a bypass to the
closest point possible on the chassis. This makes the socket and
grounds/bypasses resemble a star.


At the audio manufacturer where I worked, star grounding meant to take
all grounds to a single point on the chassis, thus having ground wires
radiate like the points on a star. This avoided ground currents
flowing through the chassis.
Brian McAllister

Sarasota, Florida

email bkm at oldtech dot net