[HomeBrew] Panadaptors
Bill Maughmer
[email protected]
Wed, 30 Jul 2003 09:03:36 -0500
I would be very interested to look at the schematic for the Panadapter. It
should be relatively easy to improve the last xtal filter and fun to build.
Bill Maughmer
WB9GOX
West Lafayette, IN
Home Purdue University
-----Original Message-----
From: [email protected]
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Sent: Wednesday, July 30, 2003 3:04 AM
To: [email protected]
Subject: HomeBrew digest, Vol 4 #51 - 7 msgs
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Today's Topics:
1. Digital Display for Rx (Doug Laidlaw)
2. RF Pad Construction Layout (Dennis L. Wade)
3. Panadaptors (WB6BLV)
4. Re: Panadaptors (Ray Anderson)
5. RE: Panadaptors (Ian Wilson)
6. comuter speakers (R. Blackman)
7. Re: RF Pad Construction Layout (Dennis L. Wade)
--__--__--
Message: 1
From: Doug Laidlaw <[email protected]>
To: [email protected]
Date: Wed, 30 Jul 2003 23:03:51 +1000
Subject: [HomeBrew] Digital Display for Rx
I am investigating a digital frequency display. It seems that TTL with a=
slow=20
update is a good compromise for counter noise. Fluorescent displays are =
NOT=20
recommended. Does anyone have experience with LCD displays?
Doug VK3KDI
--=20
Linux: in a world without fences, who needs Gates?
--and what's more, it's immune to viruses.
--__--__--
Message: 2
Date: Tue, 29 Jul 2003 08:19:05 -0700
From: "Dennis L. Wade" <[email protected]>
To: [email protected]
Subject: [HomeBrew] RF Pad Construction Layout
Hello everyone,
I want to construct an RF pad, PI section for working on receivers.
I have the appropriate values for the attenuation and impedances I
want. What I don't know is how to physically arrange the components
in such a way that I have good performance to as high a frequency as
practicable without using surface mount devices.
I am thinking of a small pc board box with a BNC connector at each
end. Can anyone give me some advice (or direct me to a place) on how
to lay this thing out well? Can I assume that modern metal film
resistors would be ok here, or do I need to use carbon comps?
Thanks!
Dennis-----------------
"If you can remain calm, you just don't have all the facts"
Dennis Wade
KG6ZI
Carmichael, CA
--__--__--
Message: 3
Reply-To: "WB6BLV" <[email protected]>
From: "WB6BLV" <[email protected]>
To: <[email protected]>
Date: Tue, 29 Jul 2003 13:29:47 -0700
Subject: [HomeBrew] Panadaptors
Many years ago I constructed a very simple Panadaptor,
so I could see about 500 KHz of each band I used. It has
been so long since I used it that I have forgotten the purpose
of the crystal in the last receiver stage of the adaptor. Anyone
who might be able to help, I will gladly send you the schematic.
As I recall, the unit samples the output of the first mixer in the\
Rx, and heterodynes it with a local HFO that is swept in sync
with the sweep of the display CRT. Then come a stage of
intermediate frequency amplification, then this crystal stage, then
a diode detector to drive the vertical plates of the CRT. I wonder
if the crystal is used as a second mixer to rescale the sample to
original frequency, since the crystal matches the offset of the HFO
from the sample exactly.
Any assistance appreciated
John
--__--__--
Message: 4
Date: Tue, 29 Jul 2003 13:37:15 -0700 (PDT)
From: Ray Anderson <[email protected]>
Reply-To: Ray Anderson <[email protected]>
Subject: Re: [HomeBrew] Panadaptors
To: [email protected]
John-
>From your description it sounds like the crystal is functioning
as a simple roofing filter to filter the output of the
mixer before it is fed to the diode detector.
A single crystal used as a filter won't provide a really
great passband shape, but will scrape off a lot of the
unwanted responses coming out of the mixer prior to
the detection stage.
73,
Ray WB6TPU
>
>Many years ago I constructed a very simple Panadaptor,
>so I could see about 500 KHz of each band I used. It has
>been so long since I used it that I have forgotten the purpose
>of the crystal in the last receiver stage of the adaptor. Anyone
>who might be able to help, I will gladly send you the schematic.
>
>As I recall, the unit samples the output of the first mixer in the\
>Rx, and heterodynes it with a local HFO that is swept in sync
>with the sweep of the display CRT. Then come a stage of
>intermediate frequency amplification, then this crystal stage, then
>a diode detector to drive the vertical plates of the CRT. I wonder
>if the crystal is used as a second mixer to rescale the sample to
>original frequency, since the crystal matches the offset of the HFO
>from the sample exactly.
>
>Any assistance appreciated
>
>John
>
>
>_______________________________________________
>HomeBrew mailing list
>[email protected]
>http://mailman.qth.net/mailman/listinfo/homebrew
--__--__--
Message: 5
Reply-To: <[email protected]>
From: "Ian Wilson" <[email protected]>
To: "'WB6BLV'" <[email protected]>, <[email protected]>
Subject: RE: [HomeBrew] Panadaptors
Date: Tue, 29 Jul 2003 13:45:56 -0700
Organization: Personal
The crystal would define the bandwidth that is being sampled, in the
same way that a crystal filter in a normal superhet. So the display at
some time would represent the energy present in a frequency slot equal
to the width of the 1-crystal filter. This slot is swept over the
500kHz (or whatever) being monitored as the HFO frequency is swept.
It would be a fun project to redo this for an LCD display rather than a
CRT.
Hope this helps
73 de ian, K3IMW/6
> -----Original Message-----
> From: [email protected]
[mailto:[email protected]] On Behalf Of WB6BLV
> Sent: Tuesday, July 29, 2003 12:30 PM
> To: [email protected]
> Subject: [HomeBrew] Panadaptors
>
> ** Please do NOT cross-post messages to multiple mailing lists on the
"To:" or "CC:" line of the e-
> mail message. **
>
> Many years ago I constructed a very simple Panadaptor,
> so I could see about 500 KHz of each band I used. It has
> been so long since I used it that I have forgotten the purpose
> of the crystal in the last receiver stage of the adaptor. Anyone
> who might be able to help, I will gladly send you the schematic.
>
> As I recall, the unit samples the output of the first mixer in the\
> Rx, and heterodynes it with a local HFO that is swept in sync
> with the sweep of the display CRT. Then come a stage of
> intermediate frequency amplification, then this crystal stage, then
> a diode detector to drive the vertical plates of the CRT. I wonder
> if the crystal is used as a second mixer to rescale the sample to
> original frequency, since the crystal matches the offset of the HFO
> from the sample exactly.
>
> Any assistance appreciated
>
> John
>
>
> _______________________________________________
> HomeBrew mailing list
> [email protected]
> http://mailman.qth.net/mailman/listinfo/homebrew
--__--__--
Message: 6
From: "R. Blackman" <[email protected]>
To: "HOMEBREW" <[email protected]>
Date: Tue, 29 Jul 2003 19:51:31 -0400
Subject: [HomeBrew] comuter speakers
Thanks to all who responded re: RFI in my speakers.
I will HOMEBREW these suggestions ( you see, this was on topic after all)
and report back. It is not the soundcard / line to the speakers. They call
CQ DX
even when not attached to the computer. I will attack the power supply next.
Item of interest: I bought some new speakers from the dollar store for
4.95$
hooked them up and the problem is 95 % gone! But now I get a huge hum /
ground loop
perhaps when splitting off a line to the radio for BPSK / SSTV / RTTY
drive.
The beat goes on.....
73, VA3NDO / Richard
--__--__--
Message: 7
From: "Dennis L. Wade" <[email protected]>
To: [email protected], [email protected]
Date: Tue, 29 Jul 2003 23:35:42 -0700
Subject: Re: [HomeBrew] RF Pad Construction Layout
Hi Joe,
Yes..I know that project well. Its been around for a while.
However, I should have been more specific about what I want to build.
What I need is a fixed pad of 12 db which has a 50 ohm input and a
120 ohm output. So, I don't have to worry about switches and the
like, but just how to arrange the components in the box.
I understand that shielding the resistors is important. Seems there
might be a way to do this with etched PC board with possibly the
shunt to ground elements (in a pi section) underneath with minimal
leads coming up and the series element on top? Maybe wide flat
traces to very short leads to/from the resistor? Comments?
I am having trouble visualizing the brass tube concepts though...
Any visual aids around? :)
Thanks for the replies...Dennis
> There was just such a project in QST a few years ago. The fellow used
> a machined out chunk of aluminum for what essentially was the chassis.
> The machining was done where switches needed the clearance and walls
> remained between the switches for shielding since crosstalk between
> switches was the limiting performance factor at low levels (high
> attenuation). DO you have past QST's?
>
> Joe N1KHB
-----------------
"If you can remain calm, you just don't have all the facts"
Dennis Wade
KG6ZI
Carmichael, CA
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