"TC Dufresne" wrote in message
...
Everyone. I fixed the VFO. Its a good news/bad news thing.

Apparently my MPF102, the heart of the VFO, was either shorted out or not
working. I removed it and replaced it with another.

Good news..Cool! Now I have a good VFO in my receiver, I can hear it in my
trusty DX-398. I adjust the RF coil so its low end (with maximum
capacitance
on my Hammerland 1-10pF variable capacitor-fully meshed) is around
7.00mHz.
When I go to minimum capacitance (no meshed), I hear it only around
7.060mHz. According to specs, I should get a range from 7.00 to 7.2mHz.

Why do I not get more range? As far as I know, all caps are up to spec as
called for.
Do I need to add/subtract capacitance somewhere?

Tolerances.

Try removing a turn from the coil (if it is one you wound) and/or adding
some capacitance.

Leon
--
Leon Heller, G1HSM

http://www.geocities.com/leon_heller

"TC Dufresne" wrote in message
...
Everyone. I fixed the VFO. Its a good news/bad news thing.

Apparently my MPF102, the heart of the VFO, was either shorted out or not
working. I removed it and replaced it with another.

Good news..Cool! Now I have a good VFO in my receiver, I can hear it in my
trusty DX-398. I adjust the RF coil so its low end (with maximum
capacitance
on my Hammerland 1-10pF variable capacitor-fully meshed) is around
7.00mHz.
When I go to minimum capacitance (no meshed), I hear it only around
7.060mHz. According to specs, I should get a range from 7.00 to 7.2mHz.

Why do I not get more range? As far as I know, all caps are up to spec as
called for.
Do I need to add/subtract capacitance somewhere?

How much did you allow for stray circuit capacitance?

TC Dufresne wrote:
Good news..Cool! Now I have a good VFO in my receiver, I can hear it in my
trusty DX-398. I adjust the RF coil so its low end (with maximum capacitance
on my Hammerland 1-10pF variable capacitor-fully meshed) is around 7.00mHz.
When I go to minimum capacitance (no meshed), I hear it only around
7.060mHz. According to specs, I should get a range from 7.00 to 7.2mHz.

You've probably got more parasitic capacitance in the circuit than that
10 pF represents. That means your capacitance range is more like 41-50
pF (figure picked out of the air) than 1-10 pF. Did the article suggest
any special construction techniques to minimize this?

--
The function of an asshole is to emit quantities of crap. Spammers do
a very good job of that. However, I do object to my inbox being a
spammer's toilet bowl. -- Walter Dnes

TC Dufresne wrote:
Good news..Cool! Now I have a good VFO in my receiver, I can hear it in my
trusty DX-398. I adjust the RF coil so its low end (with maximum capacitance
on my Hammerland 1-10pF variable capacitor-fully meshed) is around 7.00mHz.
When I go to minimum capacitance (no meshed), I hear it only around
7.060mHz. According to specs, I should get a range from 7.00 to 7.2mHz.

You've probably got more parasitic capacitance in the circuit than that
10 pF represents. That means your capacitance range is more like 41-50
pF (figure picked out of the air) than 1-10 pF. Did the article suggest
any special construction techniques to minimize this?

--
The function of an asshole is to emit quantities of crap. Spammers do
a very good job of that. However, I do object to my inbox being a
spammer's toilet bowl. -- Walter Dnes

Everyone. I fixed the VFO. Its a good news/bad news thing.

Apparently my MPF102, the heart of the VFO, was either shorted out or not
working. I removed it and replaced it with another.

Good news..Cool! Now I have a good VFO in my receiver, I can hear it in my
trusty DX-398. I adjust the RF coil so its low end (with maximum capacitance
on my Hammerland 1-10pF variable capacitor-fully meshed) is around 7.00mHz.
When I go to minimum capacitance (no meshed), I hear it only around
7.060mHz. According to specs, I should get a range from 7.00 to 7.2mHz.

Why do I not get more range? As far as I know, all caps are up to spec as
called for.
Do I need to add/subtract capacitance somewhere?
Thanks again,
Tom