开云体育

ctrl + shift + ? for shortcuts
© 2025 Groups.io
  1. Qrptech
  2. Messages
Expanded Topics Messages Polls
Date
Re: Varactor Diode C Measurement

 

I have uploaded a couple of pdfs for some diode junction capacitance comparisons that I did several years ago. They are in the K5DW directory. I used whatever I had in the junque box at the time. I only used reverse voltages up to 9 volts because I noticed that above that the capacitance flattened out considerably.

Anyways, use them or ignore them as you?see fit!

Don Wines, K5DW


On Mon, Dec 16, 2019 at 1:42 PM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote:
I'm curious how the 1n4001 compares with purpose built varactor diodes.
Figure 3 here shows it going from about 20 to 5 pf as the reverse voltage goes from 0 to 10 volts.
? ??
Would be interesting to verify that with measurements, trying several different manufacturers.

Re: 2N2222 Transceiver ala K8IQY

 

开云体育

Jerry, what would you think about using an AD831 for the first mixer?

I have one sitting here but haven’t used it yet, but the numbers quoted ( if I remember why I bought one) are a 3D order IMD of something like +24 dBm at a -10 dBm drive level. ?That might get at the Si5351 issue simply.

I should add I know nothing more about it than that little I’ve read?, but I see them starting to pop up in a few interesting projects.

Thoughts??

Scott Ka9p

Make something good happen!

On Dec 16, 2019, at 3:25 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

?I'm assuming most of what people like about the 2n2xx is due to the receiver front end and IF.
Anyone have thoughts about what would happen if the 2'd mixer was moved to an SA612?
?
Jerry, KE7ER




On Mon, Dec 16, 2019 at 01:10 PM, w8diz wrote:
Very quiet and clean sounding radio.
Re: 2n2xx Transceiver R.I.P.

 

Jerry,
Excellent observations. Thank you! Going with a NE5532 for audio like the SW-40+ rigs is a good idea. Should be plenty of gain. Plus, parts are available and inexpensive ($0.88 in single quantities).

I suppose it would be fairly simple to add a pad and amp for each synthesizer output. I'll have to do some reading to see if I can make sense of it on my own. Using a NE612 is another, maybe simpler option.?

I'm trying not to drift too far off the path.?

Mike M.? KU4QO

On Mon, Dec 16, 2019 at 2:36 PM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote:
Mike,

Very cool!

I'm trying to get dangerous with Kicad as well, it's a serious set of tools.
Being retired now, I no longer have access to the schematic editor and PADS PCB
board layout program that I had used for 30 years.
I've got a bunch of motor memory to retrain.

I believe you went with Jim's schematics from 2001:
? ??
That's a compromise, in that he was building to the arbitrary spec
of using only 2n2222's as the active device.

The Norcal schematics of 2008 made a bunch of improvements, and addressed any
issues that had come up between 2001 and 2008.
For example, looks like a much more serious bit of crystal filtering in the IF
? ??


Driving those mixers with 7dB of energy from an si5351 presents a conundrum.

The Si5351 datasheet claims it can drive 50 ohms, but then AN619 shows that
the CMOS outputs can be programmed to a max of 8ma.
The ap note is correct, the Si5351 does not do a very good job driving a 50 ohm load,
and loading it up like that will add to the crosstalk between Si5351 channels.

Those diode ring mixers want to be 50 ohms at all three ports.
With 8ma into 50 ohms, we get something on the order of 5 dBm of power.
The 7 dBm mixers will work at 5 dBm, but we're better off having a 6 dB resistive pad between the
oscillator and the mixer to absorb any unwanted spurious products coming out of the mixer and keep
them from bouncing back into the mixer to produce even more such junk.
And after adding that pad, we have lost roughly 8 dB of dynamic range off the top.
This is what the uBitx does, and it seems to work well enough.
But could do better with a buffer amp between the Si5351 and the resistive pad.

I agree about the audio transformer, there's a reason nobody sells them anymore.
Many of the audio amp IC's can drive 8 ohms directly, and might be cheaper than that transformer.

For a simple audio amp on a CW rig I'd take a look at the SW40+, includes an audio filter for CW.
If driving that amp from a diode ring mixer, you may need to add another audio gain stage up front.
? ??

The SW40+ uses an SA612 as the second mixer, we could patch that into the 2n2xx as well if so inclined.
We don't really need the dynamic range of a diode ring mixer after stripping off any QRM
with the very narrow IF crystal filter.? The SA612 would not need a buffer between it and the Si5351's output,
just a resistive attenuator to bring it down to between 200 and 300 mv into SA612 pin 6,
which has a roughly 10k input impedance.? The 14 dB of gain that the SA612 provides (vs 6 dB of loss
through a diode ring mixer)means either the audio amp or the IF amp can have 20 dB less gain,
not clear to me exactly how that extra gain should be distributed.

I'd leave the diode ring mixer up front of the IF alone, as that is what will make this better than all the SA612 rigs.

This old forgotten Philips ap note is a gold mine for those trying to understand the innards of the SA612:
? ??
Here's some history that conflicts slightly with that short piece on page one of the ap note:
? ??


Jerry, KE7ER


On Mon, Dec 16, 2019 at 08:12 AM, Michael Maiorana wrote:
Here's what I have so far. Hopefully this will be legible as an inline image. I'm a Kicad noob, so be gentle :)
I used Jim's original design with the roll-your-own mixers. This is the receiver only. There is no VFO, transmit mute or audio amp. My issue with the discrete audio amp as designed by Jim is that hard to find audio transformer. I'm not sure if I should add audio amplification to this board or just do the audio functions on a different board. Thoughts?
?
I plan to use an Si5351 ebay board and an arduino uno as a VFO/LO to get it running (commonly available code), then possibly design?a simple, low power vfo/display.
?
My intention is to use mostly surface mount parts (0805 size resistors and caps, SOT-23 size transistors and diodes).
?
Opinions are welcome!
?
Best regards,
Mike M. KU4QO
?
?
Re: Plug and Play Receiver

 

Most anything that resonates with your cap, assuming you have a bunch of wire out the window for an antenna.
The coil becomes critical when there is no wire antenna, then the bigger the ferrite rod is the more signal you scoop up,
I assume via magnetic coupling, no longer thinking microvolts into a 50 ohm antenna connector.

Back about 55 years ago, I found toilet paper rolls to make fine inductor cores for AM radio projects of this sort

Jerry, KE7ER


On Mon, Dec 16, 2019 at 01:39 PM, Michael Maiorana wrote:
Jerry,
That looks like a really fun and quick project. I've got plenty of air variable caps. Any idea what kind of coil to build if you don't have a ferrite rod for a core?
?
Adding this to my list of projects to play with!
Thanks
Mike M.? KU4QO
Re: Varactor Diode C Measurement

 

开云体育

I used a 1N4007 in my NC-40 build.
More range than the specified varactor.
The PIN structure helps.
73,
Gary?
WB6OGD?



On Dec 16, 2019, at 1:20 PM, Eric KE6US <eric.csuf@...> wrote:

?

Virtually ANY diode will work, some better than others. I have a number of projects where I used a red LED as a varactor. I usually got from low-teens pf to ~50 pf. Smaller ones tended to be better than larger ones. Red was better than other colors which have a much more limited range. The only problem I found was light sensitivity. You have to block the lens (tape, dipped in paint, whatever) or it will pick up 60 cycle variations from lighting and other weird effects.

Didn't have much luck with gp diodes. They work. Just not as much range as red LEDs. I've used them since about 2005. A couple are still plugging away and work fine.

Eric KE6US

On 12/16/2019 11:42 AM, Jerry Gaffke via Groups.Io wrote:
I'm curious how the 1n4001 compares with purpose built varactor diodes.
Figure 3 here shows it going from about 20 to 5 pf as the reverse voltage goes from 0 to 10 volts.
? ??
Would be interesting to verify that with measurements, trying several different manufacturers.

Re: 2N2222 Transceiver ala K8IQY

 

Another thought:? G0UPL and KD1JV among others are using cheap BS170's in parallel for?
a very efficient rf power amp in class E (or there-abouts).
Would be interesting to try building a class E final using BS170's in push-pull,
driven from 74ACxx gates via capacitive coupling, about 3v of DC bias at the gates.
Definitely beyond my level of competence, I might accidentally learn something.
The Peter Principle at its best.
G0UPL has some good notes on class E in his docs for the QCX.

Any thoughts on the performance of Jim's design with the 3 crystal filter vs the Norcal 2n2?

Jerry, KE7ER
Re: Plug and Play Receiver

 

Jerry,
That looks like a really fun and quick project. I've got plenty of air variable caps. Any idea what kind of coil to build if you don't have a ferrite rod for a core?

Adding this to my list of projects to play with!
Thanks
Mike M.? KU4QO

On Mon, Dec 16, 2019 at 2:56 PM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote:
Here's an unexpected curiosity for those with way too many LM386's in the junk box.
A single chip regenerative receiver.? ?
Using only an LM386:

? ??

Jerry, KE7ER

Re: 2N2222 Transceiver ala K8IQY

 

I'm assuming most of what people like about the 2n2xx is due to the receiver front end and IF.
Anyone have thoughts about what would happen if the 2'd mixer was moved to an SA612?
?
Jerry, KE7ER




On Mon, Dec 16, 2019 at 01:10 PM, w8diz wrote:
Very quiet and clean sounding radio.
Re: Varactor Diode C Measurement

Eric KE6US
 

开云体育

Virtually ANY diode will work, some better than others. I have a number of projects where I used a red LED as a varactor. I usually got from low-teens pf to ~50 pf. Smaller ones tended to be better than larger ones. Red was better than other colors which have a much more limited range. The only problem I found was light sensitivity. You have to block the lens (tape, dipped in paint, whatever) or it will pick up 60 cycle variations from lighting and other weird effects.

Didn't have much luck with gp diodes. They work. Just not as much range as red LEDs. I've used them since about 2005. A couple are still plugging away and work fine.

Eric KE6US

On 12/16/2019 11:42 AM, Jerry Gaffke via Groups.Io wrote:

I'm curious how the 1n4001 compares with purpose built varactor diodes.
Figure 3 here shows it going from about 20 to 5 pf as the reverse voltage goes from 0 to 10 volts.
? ??
Would be interesting to verify that with measurements, trying several different manufacturers.

2N2222 Transceiver ala K8IQY

 

Hi All,

Been reading the mail on Jim's 2N2222 rigs and wanting to create PCBs (for personal use only).

I'm thinking of doing one myself as I remember using one of Jims rigs (built by an FPqrp member)

Very quiet and clean sounding radio.

First, I will need to read all of Jim's docs to find the latest/greatest version of his 2N2222 rigs.

Been a looong time since I did a project for myself that did not include kitsandparts.com :)

-Diz, W8DIZ ...anticipating the fun

Hmmmmm....I have over 10K pieces of surplus MPSH10 transistors....(Jim - any thoughts?)
Re: 2n2xx Transceiver R.I.P.

 

I take that back.
Jim's schematics on? ?
still show a three crystal filter with an apparent last update of 2013

The Norcal thing is its own animal.

Jerry, KE7ER


On Mon, Dec 16, 2019 at 11:36 AM, Jerry Gaffke wrote:
I believe you went with Jim's schematics from 2001:
Re: Plug and Play Receiver

 

Here's an unexpected curiosity for those with way too many LM386's in the junk box.
A single chip regenerative receiver.? ?
Using only an LM386:

? ??

Jerry, KE7ER
Re: Varactor Diode C Measurement

 

I'm curious how the 1n4001 compares with purpose built varactor diodes.
Figure 3 here shows it going from about 20 to 5 pf as the reverse voltage goes from 0 to 10 volts.
? ??
Would be interesting to verify that with measurements, trying several different manufacturers.
Re: 2n2xx Transceiver R.I.P.

 

Mike,

Very cool!

I'm trying to get dangerous with Kicad as well, it's a serious set of tools.
Being retired now, I no longer have access to the schematic editor and PADS PCB
board layout program that I had used for 30 years.
I've got a bunch of motor memory to retrain.

I believe you went with Jim's schematics from 2001:
? ??
That's a compromise, in that he was building to the arbitrary spec
of using only 2n2222's as the active device.

The Norcal schematics of 2008 made a bunch of improvements, and addressed any
issues that had come up between 2001 and 2008.
For example, looks like a much more serious bit of crystal filtering in the IF
? ??


Driving those mixers with 7dB of energy from an si5351 presents a conundrum.

The Si5351 datasheet claims it can drive 50 ohms, but then AN619 shows that
the CMOS outputs can be programmed to a max of 8ma.
The ap note is correct, the Si5351 does not do a very good job driving a 50 ohm load,
and loading it up like that will add to the crosstalk between Si5351 channels.

Those diode ring mixers want to be 50 ohms at all three ports.
With 8ma into 50 ohms, we get something on the order of 5 dBm of power.
The 7 dBm mixers will work at 5 dBm, but we're better off having a 6 dB resistive pad between the
oscillator and the mixer to absorb any unwanted spurious products coming out of the mixer and keep
them from bouncing back into the mixer to produce even more such junk.
And after adding that pad, we have lost roughly 8 dB of dynamic range off the top.
This is what the uBitx does, and it seems to work well enough.
But could do better with a buffer amp between the Si5351 and the resistive pad.

I agree about the audio transformer, there's a reason nobody sells them anymore.
Many of the audio amp IC's can drive 8 ohms directly, and might be cheaper than that transformer.

For a simple audio amp on a CW rig I'd take a look at the SW40+, includes an audio filter for CW.
If driving that amp from a diode ring mixer, you may need to add another audio gain stage up front.
? ??

The SW40+ uses an SA612 as the second mixer, we could patch that into the 2n2xx as well if so inclined.
We don't really need the dynamic range of a diode ring mixer after stripping off any QRM
with the very narrow IF crystal filter.? The SA612 would not need a buffer between it and the Si5351's output,
just a resistive attenuator to bring it down to between 200 and 300 mv into SA612 pin 6,
which has a roughly 10k input impedance.? The 14 dB of gain that the SA612 provides (vs 6 dB of loss
through a diode ring mixer)means either the audio amp or the IF amp can have 20 dB less gain,
not clear to me exactly how that extra gain should be distributed.

I'd leave the diode ring mixer up front of the IF alone, as that is what will make this better than all the SA612 rigs.

This old forgotten Philips ap note is a gold mine for those trying to understand the innards of the SA612:
? ??
Here's some history that conflicts slightly with that short piece on page one of the ap note:
? ??


Jerry, KE7ER


On Mon, Dec 16, 2019 at 08:12 AM, Michael Maiorana wrote:
Here's what I have so far. Hopefully this will be legible as an inline image. I'm a Kicad noob, so be gentle :)
I used Jim's original design with the roll-your-own mixers. This is the receiver only. There is no VFO, transmit mute or audio amp. My issue with the discrete audio amp as designed by Jim is that hard to find audio transformer. I'm not sure if I should add audio amplification to this board or just do the audio functions on a different board. Thoughts?
?
I plan to use an Si5351 ebay board and an arduino uno as a VFO/LO to get it running (commonly available code), then possibly design?a simple, low power vfo/display.
?
My intention is to use mostly surface mount parts (0805 size resistors and caps, SOT-23 size transistors and diodes).
?
Opinions are welcome!
?
Best regards,
Mike M. KU4QO
?
?
Re: 2n2xx Transceiver R.I.P. SMT

Rob
 

开云体育

clearer comparison:
Re: 2n2xx Transceiver R.I.P. SMT

Rob
 

开云体育

About SMT.......

IF you despise SMT crumbs (as I do)? and would rather SEE what you are playing with then I suggest

the higher power devices.... like for resistors... instead of using itsybitsy 0805 ... use size

?2512 SMD Resistors.... seen in green circle in this link image:


and for transistors......

here are some sizing comparisons.....

I settled on DZT2222A-13? as my "go to" SMD transistor after losing way too many MMBT2222A to the carpet gods.



This was a water sensor project to dump air conditioner condensation overflow water:





On 12/16/2019 11:12 AM, Michael Maiorana wrote:

Here's what I have so far. Hopefully this will be legible as an inline image. I'm a Kicad noob, so be gentle :)
I used Jim's original design with the roll-your-own mixers. This is the receiver only. There is no VFO, transmit mute or audio amp. My issue with the discrete audio amp as designed by Jim is that hard to find audio transformer. I'm not sure if I should add audio amplification to this board or just do the audio functions on a different board. Thoughts?

I plan to use an Si5351 ebay board and an arduino uno as a VFO/LO to get it running (commonly available code), then possibly design?a simple, low power vfo/display.

My intention is to use mostly surface mount parts (0805 size resistors and caps, SOT-23 size transistors and diodes).

Opinions are welcome!

Best regards,
Mike M. KU4QO



On Sun, Dec 15, 2019 at 9:46 AM Mike Maiorana <zfreak@...> wrote:
Thanks Jerry.?

I spent some time this morning looking at the different versions of this rig, from the original to the Norcal version. The first thing that struck me was how crowded and complex the Norcal board looks when built. I'm sure they spent a tremendous amount of time with the redesign and layout of that board. Not for the faint of heart.?

They made some substitutions, like replacing the discrete?mixers with ADE-1 mixers. I am curious as to why Norcal kept the audio amp the way they did instead of going to a simpler integrated amp. Any ideas? They also did away with the variable bandwidth IF filter.?

I thought?it might be fun to lay out the receiver section using mostly surface mount parts. Not necessarily to get it smaller, but instead to make it less congested.?

I bought a couple of the Si5351 boards from Ebay. I could use those as the VFO, with plans to go to a more elegant (lower power) solution later.

This sounds fun, but maybe it's just because I had too much coffee this morning. I'll start adding things to Kicad and see where I end up.?

Best regards and 73
Mike Maiorana
KU4QO

On Sat, Dec 14, 2019 at 7:20 PM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote:
The Raduino used on the uBitx consists entirely of a 5v regulator, an Arduino Nano clone, an Si5351, and a standard 16x2 LCD with backlight.
Power consumption is 40ma without the display, the display (mostly the backlight) sucks another 20ma.
? ??/g/BITX20/message/52886
The linear regulator is typically powered from the main 12v supply, so that Raduino heats the room with 60ma*12v = 0.72 Watts.
Re: 2n2xx Transceiver R.I.P.

Rob
 

开云体育

It saves and displays just fine here.

Nice work.


On 12/16/2019 11:12 AM, Michael Maiorana wrote:

Here's what I have so far. Hopefully this will be legible as an inline image. I'm a Kicad noob, so be gentle :)
I used Jim's original design with the roll-your-own mixers. This is the receiver only. There is no VFO, transmit mute or audio amp. My issue with the discrete audio amp as designed by Jim is that hard to find audio transformer. I'm not sure if I should add audio amplification to this board or just do the audio functions on a different board. Thoughts?

I plan to use an Si5351 ebay board and an arduino uno as a VFO/LO to get it running (commonly available code), then possibly design?a simple, low power vfo/display.

My intention is to use mostly surface mount parts (0805 size resistors and caps, SOT-23 size transistors and diodes).

Opinions are welcome!

Best regards,
Mike M. KU4QO



On Sun, Dec 15, 2019 at 9:46 AM Mike Maiorana <zfreak@...> wrote:
Thanks Jerry.?

I spent some time this morning looking at the different versions of this rig, from the original to the Norcal version. The first thing that struck me was how crowded and complex the Norcal board looks when built. I'm sure they spent a tremendous amount of time with the redesign and layout of that board. Not for the faint of heart.?

They made some substitutions, like replacing the discrete?mixers with ADE-1 mixers. I am curious as to why Norcal kept the audio amp the way they did instead of going to a simpler integrated amp. Any ideas? They also did away with the variable bandwidth IF filter.?

I thought?it might be fun to lay out the receiver section using mostly surface mount parts. Not necessarily to get it smaller, but instead to make it less congested.?

I bought a couple of the Si5351 boards from Ebay. I could use those as the VFO, with plans to go to a more elegant (lower power) solution later.

This sounds fun, but maybe it's just because I had too much coffee this morning. I'll start adding things to Kicad and see where I end up.?

Best regards and 73
Mike Maiorana
KU4QO

On Sat, Dec 14, 2019 at 7:20 PM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote:
The Raduino used on the uBitx consists entirely of a 5v regulator, an Arduino Nano clone, an Si5351, and a standard 16x2 LCD with backlight.
Power consumption is 40ma without the display, the display (mostly the backlight) sucks another 20ma.
? ??/g/BITX20/message/52886
The linear regulator is typically powered from the main 12v supply, so that Raduino heats the room with 60ma*12v = 0.72 Watts.
Re: 2n2xx Transceiver R.I.P.

 

Here's what I have so far. Hopefully this will be legible as an inline image. I'm a Kicad noob, so be gentle :)
I used Jim's original design with the roll-your-own mixers. This is the receiver only. There is no VFO, transmit mute or audio amp. My issue with the discrete audio amp as designed by Jim is that hard to find audio transformer. I'm not sure if I should add audio amplification to this board or just do the audio functions on a different board. Thoughts?

I plan to use an Si5351 ebay board and an arduino uno as a VFO/LO to get it running (commonly available code), then possibly design?a simple, low power vfo/display.

My intention is to use mostly surface mount parts (0805 size resistors and caps, SOT-23 size transistors and diodes).

Opinions are welcome!

Best regards,
Mike M. KU4QO



On Sun, Dec 15, 2019 at 9:46 AM Mike Maiorana <zfreak@...> wrote:
Thanks Jerry.?

I spent some time this morning looking at the different versions of this rig, from the original to the Norcal version. The first thing that struck me was how crowded and complex the Norcal board looks when built. I'm sure they spent a tremendous amount of time with the redesign and layout of that board. Not for the faint of heart.?

They made some substitutions, like replacing the discrete?mixers with ADE-1 mixers. I am curious as to why Norcal kept the audio amp the way they did instead of going to a simpler integrated amp. Any ideas? They also did away with the variable bandwidth IF filter.?

I thought?it might be fun to lay out the receiver section using mostly surface mount parts. Not necessarily to get it smaller, but instead to make it less congested.?

I bought a couple of the Si5351 boards from Ebay. I could use those as the VFO, with plans to go to a more elegant (lower power) solution later.

This sounds fun, but maybe it's just because I had too much coffee this morning. I'll start adding things to Kicad and see where I end up.?

Best regards and 73
Mike Maiorana
KU4QO

On Sat, Dec 14, 2019 at 7:20 PM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote:
The Raduino used on the uBitx consists entirely of a 5v regulator, an Arduino Nano clone, an Si5351, and a standard 16x2 LCD with backlight.
Power consumption is 40ma without the display, the display (mostly the backlight) sucks another 20ma.
? ??/g/BITX20/message/52886
The linear regulator is typically powered from the main 12v supply, so that Raduino heats the room with 60ma*12v = 0.72 Watts.
Re: Varactor Diode C Measurement

 

开云体育



On 12/16/19 9:27 AM, Chuck Carpenter wrote:

For my own amazement, measured for comparison two diodes, MVAM109 and BB910.
A schematic of the N5IB design?test fixture** is attached. All stabilized at room temperature for measurement.

?????????????? Capacitance, pF
V??????? MVAM 109????? BB910
0????????? 750????????????????? 52
1????????? 481????????????????? 35
2????????? 340????????????????? 27
3????????? 234??????????????? 22
4????????? 152????????????????? 17
5????????? 100????????????????? 13
6????????? 66??????????????????? 9
7???????? 45??????????????????? 7
8???????? 33??????????????????? 6
9???????? 27????????????????????5.9
10?????? 23???????????????? 5.73
11?????? 21?????????????????? 5.59
12?????? 20?????????????????? 5.45
Highest voltage available from the battery.

The capacitance range of the BB910 is similar to the 60 pF section of a polycon often used with HF?VXOs. The MV-209 has a comparable C range.

** N5IB produced a kit of the fixture, since retired.? Fairly easy to build one from?parts on-hand.
--
Chuck, W5USJ (ex K2OFN)
Point, Rains Co, TX? EM22cv

Re: Varactor Diode C Measurement

Rob
 

开云体育

Hey Chuck..... what does this mean.... "All stabilized at room temperature for measurement."



On 12/16/2019 09:27 AM, Chuck Carpenter wrote:

For my own amazement, measured for comparison two diodes, MVAM109 and BB910.
A schematic of the N5IB design?test fixture** is attached. All stabilized at room temperature for measurement.

?????????????? Capacitance, pF
V??????? MVAM 109????? BB910
0????????? 750????????????????? 52
1????????? 481????????????????? 35
2????????? 340????????????????? 27
3????????? 234??????????????? 22
4????????? 152????????????????? 17
5????????? 100????????????????? 13
6????????? 66??????????????????? 9
7???????? 45??????????????????? 7
8???????? 33??????????????????? 6
9???????? 27????????????????????5.9
10?????? 23???????????????? 5.73
11?????? 21?????????????????? 5.59
12?????? 20?????????????????? 5.45
Highest voltage available from the battery.

The capacitance range of the BB910 is similar to the 60 pF section of a polycon often used with HF?VXOs. The MV-209 has a comparable C range.

** N5IB produced a kit of the fixture, since retired.? Fairly easy to build one from?parts on-hand.
--
Chuck, W5USJ (ex K2OFN)
Point, Rains Co, TX? EM22cv
_._,_._,_
9081 - 9100 of 9532