Date   

Re: Inductors with Same Value -- Different Results

Graham / KE9H
 

Chuck:

As a general rule, you do not want to use ferrite in a frequency determining or frequency sensitive circuit.
The value of an inductor wound on ferrite walks around with temperature, the DC current flowing through the coil, and the frequency itself.
You generally want to use the "powdered iron" type toroids for filters and tuned circuits.
The "Q" values are much higher, also.

The ferrites are for chokes, transformers, and similar, where the exact inductance is not critical.

--- Graham

==

On Thu, May 5, 2016 at 1:14 PM, John Marshall johnmars@... [qrp-tech] <qrp-tech@...> wrote:
 

Chuck,

A ferrite core can certainly affect the performance of an inductor. In addition to increasing the inductance of a coil at the operating frequency (as compared to air), ferrite can increase its resistance. This may be desirable in some applications. For example, in beads or chokes used for decoupling the resistive component lowers the Q of the inductor and dissipates some of the unwanted signal. OTOH, added resistance in a filter is exactly what you don't want. There are lots of different ferrites with different L and R profiles for different frequencies.

Here's a link to a page at Clifton Labs that almost perfectly addresses your issue with the FT23-43 toroid:
< http://www.cliftonlaboratories.com/estimating_q_of_ferrite_cores.htm >

Hope this helps,

John, KU4AF
Pittsboro, NC

On May 5, 2016, at 10:27 AM, Chuck Carpenter w5usj@... [qrp-tech] wrote:

> At least in the 7MHz/2.5 MHz Band Pass Filter I've been experimenting with.
>
>
> The filter is being used in a circuit similar to the Pixie but with a
> few more bells and whistles.
>
>
> One of the inductors in the series circuit is nominal 6.2 uH. I
> didn't have that value on hand so I wired 3.9uH and 2.2uH Fastron RF
> chokes in series for a measured 6.7 uH. I plugged them in and the
> filter seems to work OK with that value. The other two chokes are
> wound on T30-6 cores and adjusted for as close to .39 uH as I could get them.
>
>
> I'm using an AADE L/C meter at whatever frequency it measures with.
>
>
> So, I then wound a measured 6.5 uH inductor on an FT23-43 core and
> plugged that into the circuit. The power output dropped to 1/2 of
> what it had been.
>
>
> Next I tried a small RF choke marked as 6.5 uH of unknown
> manufacture. Same results as the toroid inductors.
>
>

> Put the original series pair of chokes back in the circuit and all
> was well again.
>
>
> It's possible the small inductor has a ferrite core. Is it possible
> that ferrite has something to do with the inductors that didn't work?
>
>
>
>
> Chuck Carpenter, W5USJ
> EM22cv, Rains Co. TX



Re: Inductors with Same Value -- Different Results

John Marshall KU4AF
 

Chuck,


A ferrite core can certainly affect the performance of an inductor. In addition to increasing the inductance of a coil at the operating frequency (as compared to air), ferrite can increase its resistance. This may be desirable in some applications. For example, in beads or chokes used for decoupling the resistive component lowers the Q of the inductor and dissipates some of the unwanted signal. OTOH, added resistance in a filter is exactly what you don't want. There are lots of different ferrites with different L and R profiles for different frequencies.


Here's a link to a page at Clifton Labs that almost perfectly addresses your issue with the FT23-43 toroid:
< http://www.cliftonlaboratories.com/estimating_q_of_ferrite_cores.htm >



Hope this helps,


John, KU4AF
Pittsboro, NC

On May 5, 2016, at 10:27 AM, Chuck Carpenter w5usj@9plus.net [qrp-tech] wrote:


At least in the 7MHz/2.5 MHz Band Pass Filter I've been experimenting with.


The filter is being used in a circuit similar to the Pixie but with a
few more bells and whistles.


One of the inductors in the series circuit is nominal 6.2 uH. I
didn't have that value on hand so I wired 3.9uH and 2.2uH Fastron RF
chokes in series for a measured 6.7 uH. I plugged them in and the
filter seems to work OK with that value. The other two chokes are
wound on T30-6 cores and adjusted for as close to .39 uH as I could get them.


I'm using an AADE L/C meter at whatever frequency it measures with.


So, I then wound a measured 6.5 uH inductor on an FT23-43 core and
plugged that into the circuit. The power output dropped to 1/2 of
what it had been.


Next I tried a small RF choke marked as 6.5 uH of unknown
manufacture. Same results as the toroid inductors.

Put the original series pair of chokes back in the circuit and all
was well again.


It's possible the small inductor has a ferrite core. Is it possible
that ferrite has something to do with the inductors that didn't work?




Chuck Carpenter, W5USJ
EM22cv, Rains Co. TX


Re: Inductors with Same Value -- Different Results

Nick Kennedy
 

​I've always thought that the AADE would not give good readings with ferrite due to the lower frequency of measurement.  Plus, ferrite is not usually good for filters due to the low Q.

Hey Chuck, now that I've got your attention - get out your style book. Which is preferred when referring to surface mount, SMT or SMD?

73-

Nick, WA5BDU​


On Thu, May 5, 2016 at 9:27 AM, Chuck Carpenter w5usj@... [qrp-tech] <qrp-tech@...> wrote:

It's possible the small inductor has a ferrite core. Is it possible
that ferrite has something to do with the inductors that didn't work?

Chuck Carpenter, W5USJ
EM22cv, Rains Co. TX




Inductors with Same Value -- Different Results

Chuck Carpenter <w5usj@...>
 

At least in the 7MHz/2.5 MHz Band Pass Filter I've been experimenting with.


The filter is being used in a circuit similar to the Pixie but with a
few more bells and whistles.


One of the inductors in the series circuit is nominal 6.2 uH. I
didn't have that value on hand so I wired 3.9uH and 2.2uH Fastron RF
chokes in series for a measured 6.7 uH. I plugged them in and the
filter seems to work OK with that value. The other two chokes are
wound on T30-6 cores and adjusted for as close to .39 uH as I could get them.


I'm using an AADE L/C meter at whatever frequency it measures with.


So, I then wound a measured 6.5 uH inductor on an FT23-43 core and
plugged that into the circuit. The power output dropped to 1/2 of
what it had been.


Next I tried a small RF choke marked as 6.5 uH of unknown
manufacture. Same results as the toroid inductors.


Put the original series pair of chokes back in the circuit and all
was well again.


It's possible the small inductor has a ferrite core. Is it possible
that ferrite has something to do with the inductors that didn't work?




Chuck Carpenter, W5USJ
EM22cv, Rains Co. TX


Re: ChiPixie first QSO!

gj7rwt
 

Well done Kurt.


If you change Q1 to a 2n3904 you will get nearly 800mw out at 12v and 1.2w at 13.8v


73's
De Andy
--------------------------------------------

On Wed, 5/4/16, rhulett1@consolidated.net [qrp<qrp-tech@yahoogroups.com> wrote:


Subject: [qrp-tech] ChiPixie first QSO!
To: qrp-tech@yahoogroups.com
Date: Wednesday, May 4, 2016, 8:21 PM

First QSO with ChiPixie @
300 mW with 7.050 xtal, 150 miles to Austin, K5BOTgave me a
339 :-)   

RBN W7AH n AZ
hrd me this morning @ 3 dB, AC0C n KS has heard me as much
as 15 dB.  Plan to use this radio for SKCC WES this
weekend, being a glutton for punishment.  Last WES, used a
"Tixie" for grand total of 3 QSOs

72, Curt KB5JO


ChiPixie first QSO!

rhulett1@...
 

First QSO with ChiPixie @ 300 mW with 7.050 xtal, 150 miles to Austin, K5BOTgave me a 339 :-)   

RBN W7AH n AZ hrd me this morning @ 3 dB, AC0C n KS has heard me as much as 15 dB.  Plan to use this radio for SKCC WES this weekend, being a glutton for punishment.  Last WES, used a "Tixie" for grand total of 3 QSOs

72, Curt KB5JO



Re: 30 Meter XCVR Identification

Mike Czuhajewski
 

Carl, I'll scan the manual and send it to you. It's pretty minimal.
The radio my friend had turned out to be the kit from Circuit Board
Specialists (for 40M in this case), not the one from Small Parts
Center, and it clearly identified as the W7EL design (with a few
updates).


This version is a bit nicer; the main board is plated and the front
and rear panels, also made of PCB material, have legends etched in
them for the connectors, controls, etc. The panels were not plated but
probably have clear varnish or something on them since the copper is
still nice and clean. (The one from SPC didn't have anything on any of
the copper, so it doesn't look nearly as good.)


The manual says the keyer circuit came from the May 1980 issue of QST;
the article is titled "The NOR-Gate Break-In". I can't remember if the
SPC version included the keyer or not. The CBS version includes a
simple paddle cut out of PCB material, sticking out of a slot on the
front panel. (Pieces of wire are used for the contacts.)


73........


Re: 30 Meter XCVR Identification

ka9gpx
 

Well,...

Looks like you guys called it. Definitely has the appearance of the W7EL Optimized Transceiver. And possibly the "New & Improved / Updated" Small Parts version that Mike recognized.

Uses slightly updated components such as the SBL-1 Mixer Hybrid,... and like Pete suggests,.. I also agree with 4001's being part of the "Built-In" keyer,...  Kinda the Mark IV version.

Looking forward to seeing what your friend may be able to supply with respect to the original manual Mike,... NO Hurry at all,... At least I now have a place to start knowing it is probably a derivative of the W7EL Classic.

Thanks again to ALL that replied,...
Anxiously awaiting Mike's reply...8-)

Carl
AA9RF
ex KA9GPX


May NorCal Meeting

Doug Hendricks <ki6ds13@...>
 


The regular monthly meeting of the NorCal QRP Club will be held at Denny's, 1140 Hillsdale, in San Jose tonight Tues. May 3. We get together for a nohost dinner at 6:30 and then we have qrp show and tell, visiting, and a surprise or two. This month we will start the Pixie Project. I have 20 Pixie kits to give away. The capacitors have been replaced with good ones that meet specs. Darrel Swenson who is on the NorCal Board, supplied us with 7.040 MHz crystals, so each kit will have 2 crystals, 7.040 and 7.023. I also put a 3 pin sip socket in each kit so you can change frequency. The goal is to have everyone build their Pixie and bring it to the June meeting. At the June meeting you will get the second kit in the series, the Pixie Whip. Then in July you will get the Pixie Band Pass Filter, and in August we will have a QSO party using our Pixies and Dummy Load antennas (Pixie Whips). It's going to be a lot of fun so you don't want to miss out. Last month I passed out RF Probe kits. Hopefully I will get to see the fruits of my effort this month. Be sure to bring your built RF Probe to the meeting. Remember the goal is to have fun in life and build radios!! See you at Denny's. 72, Doug, KI6DS

Sent from Yahoo Mail for iPhone


Re: 30 Meter XCVR Identification

neil tanner
 

Good call Mike.  I tried building this years ago.....just the rx portion.   Had the schematic from a back issue of QST.  Never got it to work.....wish I had, would have liked to compare it with other DC rcvrs I made.
72 Neil wa4chq


Re: QRP Guys RF Probe

aa6ki@...
 

If anyone here hasn't read the manual yet, be aware that this device is NOT intended as a power meter.  Its purpose is to provide relative indications of the RF present in a circuit.

I received my kit on Saturday, and after dealing with a bout of food poisoning, finished it yesterday. Agree about the difficulty installing the jumper over the resistor at the rear of the meter.  I managed to get it done, but it was more by luck than by skill.

Soldering the small ICs went well for me. I use the "drag-a-blob" method, where you drag the solder across the pins, not worrying about solder bridges. Then you go back with some solderwick and clean it up. And maybe my soldering iron runs hotter than yours.

I had no problem positioning the rubber feet as recommended.

There are photos of the top and bottom of my probe in the album under my call, AA6KI.

I've done only some quick testing, but it appears to be working just fine.

Jerry AA6KI
Tucson





Re: 30 Meter XCVR Identification

Mike Czuhajewski
 

I put photos of the Transceiver in an AA9RF Album.....

I recognized it instantly. It's basically the W7EL Optimized QRP
Transceiver from the August 1980 issue of QST. I had one once, for a
while, that I picked up already assembled. I believe the kit came from
Small Parts Center in Michigan, long out of business. I sent mail to
the person who I gave it to, to see if he still has the manual. He
does, and I'll be getting it from him in a day or two. (He says it's
just 4 pages.)


73......


Re: 30 Meter XCVR Identification

neil tanner
 

Good find Carl!
If you have access to Solid State Design for the Radio Amateur or any of the Doug DeMaw books, I bet you may find it in there.  The original builder may have taken a 40m rig shown in one of those books and built it for 30m.  Or, he may have taken ideas from both books and designed his own rig.   To me, the layout looks like something I've seen in DeMaws books.  It may have come from early issues of QRPp or even HamBrew.....
Good luck with it. 


Re: 30 Meter XCVR Identification

zx97lite@...
 

Perhaps a modified W7EL Rig (Aug '80 QST).  The CMOS chips are probably the keyer.  Here is one version of Roy's Rig from 73 Magazine:


This one includes component values for 30 Meters.  Included is a circuit board layout but it is different from the one in your picture.

Pete  WB9FLW


 




30 Meter XCVR Identification

ka9gpx
 

Hello All,...

I know this might be a long shot,.. But I am looking for help in trying to identify a 30Meter Transceiver "project" that I recently obtained at a Garage Sale.

I put photos of the Transceiver in an AA9RF Album. I have included pictures of the Front of Cabinet / Controls, as well as some of the PC Board. The device sorta works... Has about 1.5W output, but Poor Receive. (on the order of 10-12uv.)

The story I was told is that the gentleman that built the project (SK),... was an avid QRP builder from Magazine articles. The seller had no paperwork to go with the XCVR.

Here's some info about Project... Appears to be a Direct Conversion device.. (NO Xtals present) I.C.'s include 2-TL072CP,... 1- LM301AN,...2- 4001B-CMOS I.C.s,... 1-SBL-1 Mixer Hybrid,.  Output transistor is a 2N3553. PC Board is etched on bottom,... Slightly on top,... Has many of the holes "countersunk" where component leads pass through board.. Suspect "4001B's" are used for built in keyer circuit.

So I'm wondering if anybody might recognize this Transceiver from about 20+ years ago,-- My guess--base on parts used,... and type of PC Board construction.-- Don't see that "countersinking used much anymore....
Looked in some of the older 73 & QST magazines I had access to,... No Luck,... Could have missed it... Maybe from Ham Radio or CQ ???

Any help would be most appreciated.
Sorry for the "Long-Winded-ness"

Carl
AA9RF
ex KA9GPX




Re: Four Conductor Transmission Line

AD7ZU <ad7zu@...>
 

Ed,

A long time back .. 1980 or so?  I  built a 4 wire transmission line to drive a folded dipole at a height of less than a 1/2 wave. at that height the impedance is well under 280 ohms. .. and a good fit for a 4 wire line.  A 4 wire line might also closely match some of the skywire loop designs. 

There are several advantages:

 the impedance is lower.   maybe about 35% of a similar sized 2 wire open line (as i remember) would be a good estimate. but check the formula.  it should be in the ARRL antenna book?

There is less sensitivity to the orientation of the transmission line to ground.

 The losses are lower, but with an open wire line the difference is probably negligible.

 The power handling is higher but that isn't an issue for us QRPers


Randy
AD7ZU



From: "J Ed jedwardsat1@... [qrp-tech]"
To: qrp-tech@...
Sent: Friday, April 29, 2016 9:54 PM
Subject: [qrp-tech] Four Conductor Transmission Line

 
The ARRL antenna book I have describes a type of open wire ladder line using four wires arranged in a square. The wires are basically two pairs of parallel conductors at right angles. Benefits should include less copper losses and increased balance with regard to nearby conductive objects. The only reason I can see for not doing this is the increased materials needed.
Has anyone ever used four conductor ladder line in their station? If open wire line is low loss, four wires should be even better. For QRP, this should be helpful.
Ed AE7TE



Re: QRP Guys RF Probe

bobledoux@...
 

This a further followup to my kit construction:

Other than the challenge getting the AD8307 chip soldered the rest of the kit went well.

A small resistor on the back of the display must be jumpered to provide the correct voltage range.  The instructions suggest placing a piece of wire wrap wire over the resistor and soldering in place.  When I attempted to do this, with my smallest SMD solder tip I managed to unsolder the resistor. Removing the resistor made the jumper process easy.

It would be nice to silkscreen a table or chart to convert the display readings into dbm.  I think there is room between the display mounting screws on the back of the circuit board.

The instructions say to place the two rubber feet beside each other.  The feet are too big so one goes under the rear battery case and under the two inductors up front.

This is a quality kit, but it requires some experience with SMD soldering.

bob-N7SUR 


Re: ChiPixie heard by RBN

rhulett1@...
 

Output sagging badly after running for awhile, replaced Q2 with a real from my stock 2222.  Better now.  Still hoping for a QSO soon. 

BTW, no wonder AC0C heard me after seeing his station on QRZ.  Enough gear and antennas for ten hams, if he can't hear you cant be heard anywhere on the planet.

72, Curt KB5JO


Re: Four Conductor Transmission Line

Kirk, NT0Z
 

Ed and the gang,

This stuff IS interesting...and is mostly used at VHF as an alternative to expensive coax or hard line. At HF, losses on a good two-conductor open-wire line are low enough to not warrant bothering with 4-conductor line -- which is more difficult to physically install and terminate.

A caption to a column I wrote a while back has the source info:

"Need a low-loss, 300-foot-long feed line for your 2-meter Yagi that won't require robbing your college fund (or a cable TV truck)? The four-wire open-wire line shown here (author's full size mock-up made from slices of 2 X 2 lumber and string trimmer line) has loss characteristics that rival 7/8-inch hard line (about $5 a foot and $30 each for connectors), but at a fraction of the price. With two-inch spacing between the wires, this easy to build feed line has a 200-ohm impedance, which makes for an easy match to 4:1 baluns, and only 0.6-dB loss per 100 feet at 144 MHz. Henry Elwell Jr. N4UH, provides details in the January 1987 and October 1980 issues of Ham Radio magazine. (NT0Z photo)"

Regards,

--Kirk, NT0Z


QRP Guys RF Probe

bobledoux@...
 



These guys are a list of Who's Who of kit builders and designers.  I just had to have the AD8307 RF signal probe.  I hope there are new kits in the pipe line.

I received my kit two days ago.

This morning I completed installation of the surface mount devices after reading Steve Ratzlaff's review in message #11208.

The pads have some mass so the soldering iron needs to provide some heat.  I used a larger than normal SMD tip on my Hakko 936.  I also applied flux from a pen before soldering.

The LM358 soldered very nicely.  But the AD8307 was a different story.  The IC pins were reluctant to take solder.  When the flux pen didn't work I added some liquid flux from a bottle with a brush.  I finally got contract when I resorted to solder with 2% silver.  My normal solder is 63-37 tin-lead.

The 1206 components soldered fine. 

I'm building my kit, stock.  I'll see how it works before considering Steve's changes.

bob-N7SUR


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