KitsAndParts.Com Forum

W8DIZ · 2008-08-12 14:15:02

Build these Universal Band Pass Filters for $8.
Available for 10, 12, 15, 17, 20, 30, 40, 80 and 160 meters.

http://kitsandparts.com/univbpfilter.php

-Diz, W8DIZ

ak2b · 2009-04-27 12:49:08

40M 7pole BPF
-3db BW = 250Khz
-6db BW = 289Khz

WY7N · 2009-06-24 17:29:37

What is the tune/alignment procedure for these BPFs?

W8DIZ · 2009-06-25 06:47:43

WY7N wrote:
What is the tune/alignment procedure for these BPFs?

Being that the filters were designed to be tight narrow pass filters for CW portions of the bands,
all you need to do is adjust the trimmer caps for maximum signal at your favorite frequency.
For the 40 meter band, I would use 7030 as the center freq.
73, Diz, W8DIZ

WY7N · 2009-06-25 07:14:42

Thanks!

I hope to try them out this weekend during Field Day. I'll return and report.

WY7N · 2009-06-25 07:16:31

Two more questions. Is it necessary to mount them in a shielded enclosure? And... what is their power handling capability?

Thanks again in advance!

W8DIZ · 2009-06-26 05:21:19

WY7N wrote:
Two more questions. Is it necessary to mount them in a shielded enclosure? And... what is their power handling capability?

Enclosure is not required.
The rating is set by the capacitors. They are rated as 50 working volts which means they can probably handle 100 volts peak voltage.
So figure out what the maximum voltage would be on any of the caps with a very bad SWR.
I would only use the filters with 10 watts or less power.

73, Diz, W8DIZ

py1nb · 2009-07-12 04:14:07

Hi,

What is the typical insertion loss?

73 PY1NB

W8DIZ · 2009-07-12 07:17:02

py1nb wrote:
Hi,
What is the typical insertion loss?
73 PY1NB

Depends on the band and the bandwidth measured but 5 dB is about normal.
73, Diz, W8DIZ

SM7FBJ · 2009-12-14 03:10:33

Hi

What size of wire is used in theese kits?

http://www.partsandkits.com/univbpfilter.php

I have som different magnetic wires to choose from. I'm planning to build the BPF for 80m and it will be for QRP, the T50-2 core will be used.

Regards
Barney SM7FBJ

Last edited by SM7FBJ (2009-12-14 05:37:47)

SM7FBJ · 2009-12-15 14:28:11

I couldn't make the BPF work properly, the magnetic wire (AWG 30) got hot at only 5W. The SWR into the BPF grew higher after a few seconds......but in receive mode I could clearly adjust it.

73 de Barney/SM7FBJ

ak2b · 2009-12-15 15:46:11

Hi Barney,
Are you using the BPF something like this?

--->Transmitter --->BPF ---LPF --->Ant

or

--->Transmit Mixer --->BPF --->Transmitter --->LPF --->Ant

In receive mode the BPF is used like this

--->Ant --->LPF --->BPF --->RF amp or receive mixer

Diz's Transmit mixer http://www.kitsandparts.com/xmit_mixer.php provides a way to switch the BPF between transmit and receive.

Tom, ak2b

SM7FBJ · 2009-12-16 02:11:10

Hi Tom

I Have built a 2 tube transmitter (osc and pa) and when transmitting on 80m I want to have as little harmonic as possible on higher bands, the power is a bit less than 10W. I looks like this: --->transmitter --->BPF --->Ant. Maybe I'm using the BPF in an unsuitable way? The magnetic wire on the core closest to the transmitter is getting warm.

73 de Barney

Tube transmitter

Last edited by SM7FBJ (2009-12-16 02:16:35)

ak2b · 2009-12-16 08:46:49

Hi Barney,

Nice job on the transmitter build. It looks great.
In my day, the transmitter you have built would be ready to go as is. Assuming you are tuned properly, the tank circuit should keep harmanics down to a safe level. If you think you need additional transmit filtering I would read the the articles Diz has posted here http://www.partsandkits.com/W3NQN_filter.php. My inclination would be to get on the air and have some fun

Tom, ak2b

SM7FBJ · 2009-12-16 11:59:56

Ok Tom

You are probably right there. I'm using a single-coil Z-match to my ladder fed bouble zepp, and it will work as an additional filtering too. I never got any answer on my question on the dimension of the magnetic wire in the BPF, but I'll get going as it is then. Thanks for a fine resonse.

Barney,SM7FBJ

ak2b · 2009-12-16 15:03:08

Hi Barney,

I would guess that the wire size is about #26 or #27 or close to that - not #30. You could use up to about #22 wire for 34 turns on the T50-2's according to my calculator. Diz answered the power handling question on another post on this page.

w8diz wrote:
The rating is set by the capacitors. They are rated as 50 working volts which means they can probably handle 100 volts peak voltage.
So figure out what the maximum voltage would be on any of the caps with a very bad SWR.
I would only use the filters with 10 watts or less power.

Tom, ak2b

P.S. I looked at the info on this site (which is your TX) and I believe you are in good shape without the BPF.
http://www.algonet.se/~janax/ecl82bug.htm

SM7FBJ · 2009-12-16 15:50:01

Hi Tom

Thanks for your engagement Tom.....

Barney,SM7FBJ

wa2mze · 2009-12-16 17:15:14

Nice transmitter. Looks like one that was in QST, or 'how to become a radio amateur'. I see you moved the xtal socket from on top of the chassis to the front panel. A friend of mine build one as a novice, it had a 6c4 and a 5763 in it.

In 2008 my family and I took the auto-train up to NYC. We drove from DC to NYC. While in the DC area we visited with some friends and got to see the spy museum. The museum had lots of cool stuff, including some suitcase cw transceivers that could have been used in war time. IIRC, the transmitter was a one or two tube xtal controlled rig with a 6L6M final. The receiver was a simple rig, probably a regen detector with a superhet front end. I've been thinking of building a rig like that. There was a simple superhet in QST back in the 40's that could be the basis for the receiver. A 6K7 mixer/oscillator would be followed by a 6SJ7 regen detector, and maybe a 6G6G audio stage. The transmitter could have a 6AG7 oscillator and a 6L6 or 807/1626 in the final. Maybe add one more stage to the transmitter, a 6AC7 vfo/vxo and use the 6AG7 as a multiplier / driver. The whole thing would fit into an old attache case. It would make a nice QRP rig.

Last edited by wa2mze (2009-12-16 17:18:49)

SM7FBJ · 2009-12-18 04:31:35

Thanks Ken

The transmitter uses a 6C4(EC90) as oscillator and 6BQ5(EL84) as PA. The receiver I built to this TX, is with two Heptode/triode tubes 6AJ8(ECH81). It's a super with a regen detector. I have made one contact with this setup.

I will probably try to change the magnetic wire to a bigger one in the T50-2 cores, even if I not have to use the BPF, it's nice to try building it.

Last edited by SM7FBJ (2009-12-18 04:34:28)

wa2mze · 2009-12-18 08:41:28

Interesting receiver, do you have the schematic? Any under chassis photos? What IF frequency?
I never heard of the 6AJ8, probably a European designed tube, maybe used in Grundig radios.

SM7FBJ · 2009-12-18 09:40:42

I'll have to scan the schematic, but the IF frequency is 1700kHz, and the the oscillator is between 5,2-5,7Mhz. The tuned HF part works both on 80 and 40m. I'll come back with some pics of the building and the schematichs.

The tube number you didn't know, I got from a translationsite on the net. It's a ECH81 (heptode/triode)

Last edited by SM7FBJ (2009-12-18 09:41:58)

wa2mze · 2009-12-18 09:47:41

Yes, the classic band imaging receiver. There were many of these described in QST and the HB over the years.

SM7FBJ · 2009-12-18 11:49:42

I built theese 2 "boxes" because I like tubes, and it's fun. I have made over a couple of hundreds QSO:s with the transmitter, and one over seas QSO to the USA on 20m (first harmonic of the 7010kHz crystal)

The schematic. C2 has been replaced with fixed capacitors in parallell

To the most left is the signal circuit, then the oscillator circuit. The tubesocket to the right is the detector/LF-stage, and the mixer/oscillator to the left. I don't know why the pics can't be seen.....copy and paste the URL into your browser

Last edited by SM7FBJ (2009-12-19 09:59:29)

ak2b · 2009-12-19 06:47:46

Hi Barney,

Your pictures were not showing up even though there is nothing wrong with the URL's.
I moved the pictures to my web server and point to them with the same image tag. I tried the URL's on another web page (cutting an pasting) and they work fine. If you click on the url from inside the forum you get pop-ups and other images on the page. My guess is that the fourm software has a problem with that.

Tom, ak2b

http://hem.passagen.se/bbirch/super.jpg produces pop-ups

<http://hem.passagen.se/bbirch/inside.jpg> cutting and pasting the url works fine without the pop-ups

KitsAndParts.Com Forum

#1 2008-08-12 14:15:02

BPF - SIngle band Band Pass Filters - 7 Pole

#2 2009-04-27 12:49:08

Re: BPF - SIngle band Band Pass Filters - 7 Pole

#3 2009-06-24 17:29:37

Re: BPF - SIngle band Band Pass Filters - 7 Pole

#4 2009-06-25 06:47:43

Re: BPF - SIngle band Band Pass Filters - 7 Pole

WY7N wrote:

#5 2009-06-25 07:14:42

Re: BPF - SIngle band Band Pass Filters - 7 Pole

#6 2009-06-25 07:16:31

Re: BPF - SIngle band Band Pass Filters - 7 Pole

#7 2009-06-26 05:21:19

Re: BPF - SIngle band Band Pass Filters - 7 Pole

WY7N wrote:

#8 2009-07-12 04:14:07

Re: BPF - SIngle band Band Pass Filters - 7 Pole

#9 2009-07-12 07:17:02

Re: BPF - SIngle band Band Pass Filters - 7 Pole

py1nb wrote:

#10 2009-12-14 03:10:33

Re: BPF - SIngle band Band Pass Filters - 7 Pole

#11 2009-12-15 14:28:11

Re: BPF - SIngle band Band Pass Filters - 7 Pole

#12 2009-12-15 15:46:11

Re: BPF - SIngle band Band Pass Filters - 7 Pole

#13 2009-12-16 02:11:10

Re: BPF - SIngle band Band Pass Filters - 7 Pole

#14 2009-12-16 08:46:49

Re: BPF - SIngle band Band Pass Filters - 7 Pole

#15 2009-12-16 11:59:56

Re: BPF - SIngle band Band Pass Filters - 7 Pole

#16 2009-12-16 15:03:08

Re: BPF - SIngle band Band Pass Filters - 7 Pole

w8diz wrote:

#17 2009-12-16 15:50:01

Re: BPF - SIngle band Band Pass Filters - 7 Pole

#18 2009-12-16 17:15:14

Re: BPF - SIngle band Band Pass Filters - 7 Pole

#19 2009-12-18 04:31:35

Re: BPF - SIngle band Band Pass Filters - 7 Pole

#20 2009-12-18 08:41:28

Re: BPF - SIngle band Band Pass Filters - 7 Pole

#21 2009-12-18 09:40:42

Re: BPF - SIngle band Band Pass Filters - 7 Pole

#22 2009-12-18 09:47:41

Re: BPF - SIngle band Band Pass Filters - 7 Pole

#23 2009-12-18 11:49:42

Re: BPF - SIngle band Band Pass Filters - 7 Pole

#24 2009-12-19 06:47:46

Re: BPF - SIngle band Band Pass Filters - 7 Pole

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