[HBR] HB 67 Receiver Introduction

Mon, 8 Apr 2002 17:39:30 -0500

All-
First a quick introduction: name here is Cliff White WB5DYA and the QTH is
Cedar Park Texas within a few miles of Kees.

I visited with Kees this weekend on the subject of constructing a tube ham
bands only receiver with enough performance to encourage regular use on the
bands.  My assessment is that the typical earlier designs detailed on Kees'
website would not yield enough performance to meet my criteria.

Years ago (1964) while in undergraduate school, I read and got very
interested in the "miser's dream receiver" article and followed the
subsequent articles with a great deal of interest.  This receiver design
followed the principles outlined in a couple of the earlier articles from
Goodman and Squires about a different approach toward receiver design.

Years later (1974) bought a used commercial version of this receiver at the
Dallas sidewalk in real bad shape.   I am talking about a Hallicrafters
receiver model SX-146.  This receiver is very close to the "miser dream"
with the following modifications:  
* Added a RF stage
* Low gain RF amplifier followed by low noise triode mixer
* Band switching
* Did not use 7360 beam deflection tube
* Single conversion with IF at 9.0 MHz
* All selectivity provided by a single crystal filter
* Switched filters for each mode: CW, SSB, AM
* Very simple mechanical & electrical design 

I am very interested in building a single conversion receiver very similar
to the miser's dream or HB-67.  My design parameters are:
* Basic single band 20 meter receiver
* Use an external vacuum tube crystal controlled converter to cover other
bands 
* Probably  mounted in a separate cabinet with a speaker and some form
adjustable passive audio filter and speaker 
* Include adjustable attenuator in crystal converter design
* Design around low noise tubes/circuits 
* Possibly an external power supply to reduce size and enable use of
aluminum cabinet for receiver
* Running a 7360 mixer in same cabinet with power transformer without a lot
of steel or mu-metal shielding will result in 120 Hz modulation of the
electron beams in the tube with resulting hum 
* Power supply could fit into a separate steel cabinet with speaker and
crystal controlled converter or 
* Emphasis on simple mechanical design 
* Aluminum metal for receiver and converter
* Steel chassis or steel shielding for power supply
* Good dial mechanism (probably an Eddystone since I have a couple)Include
an low noise RF amplifier stage
* Switchable RF attenuator between antenna terminal and RF amplifier
* Retain the basic 7360 tube mixer circuit for superior mixer performance
* Single conversion at 9.00 MHZ (I have some 9.00 MHz SSB & CW filters and
crystals)
* Use small relays to switch between filters (this simplifies construction
and front panel layout)
* Probably have some form of tail end filter before the product mixer for
SSB and CW 
* This may require an additional stage of IF amplification
* Having three stages is good news since this provides a much greater AGC
range
* Probably no provisions for AM unless I can find some AM filters which are
difficult to find
* Dual balanced diode product detector
* This will probably require a cathode follower as the last stage of IF
amplification for impedance matching
* Some form of audio low pass filter after product detector to reduce hiss 
* AGC applied to RF amplifier and all IF amplifiers using some form of low
impedance circuit in tube cathode circuits
* This approach  is described in some 73 or CW magazines of which I have
copies
* I modified an old HQ-110 years ago with good success.
* IF notch filter using tuned crystal to ground using circuit from Yaesu
FT-301/FT-902 (this is a very simple circuit with a crystal in series with a
variable capacitor shunted to ground)
* Some form of RIT if at all possible for us with a matching CW/SSB
transmitter to be designed in the future

And so on.  

I would be glad to communicate with anyone wanting to build any receiver
similar to the HB-67 or something improved.   I think we can buy additional
SSB/CW  6 pole 9.0 MHz filters and matching oscillator crystals cheap from
England.   If interested, I will send copies of schematics and articles that
I think would apply to this receiver project. 

In short, I want to build a high performance receiver system that justifies
the effort.   I want to build a receiver I will use on the air and could use
as a possible building block for a subsequent transmitter project.

Thanks and CUL - Cliff

 -----Original Message-----
From: 	Diane Swynar [mailto:[email protected]] 
Sent:	Monday, April 08, 2002 12:44 PM
To:	[email protected]
Cc:	[email protected]; [email protected]
Subject:	Re: [HBR] HB 67 Receiver or others like that under
construction

Hi Kees & Darrell...

Well, count me in as one who is building that rig--or at least, a version
thereof...

I have, I believe, ALL of the parts in hand now, but plan on a few changes,
including:

-The addition of a 3rd IF stage;
-A p-p pair of 6AQ5's in the final AF stage;
-A switchable AM diode detector in addition to the product detector, and,
-More than one switchable mechanical/crystal bandpass IF filter.

I'm one project away from starting this one---first up is a 1929-style
superhet, as inspired by Lindsay's piece in the newest issue of THE OLD
TIMER'S BULLETIN. This is the one that uses REAL glow-in-the-dark
bottles...things like 224A's, 227's, & 245's!

Will keep you guys posted---please do likewise for my benefit!

~73~ Eddy VE3CUI - VE3XZ

> One of the guys at the Williamson County ARC is interested in
> building a HB 67 or similar unit (I believe Darrell is building one).
> He's not on the reflector and would like to hear from some of you  to
> discuss it's design points. Please respond to him directly and
> copy the HBR reflector, since we're all interested. His e-mail
> is     [email protected]
>
> 73s  Kees K5BCQ
>
> ************************************
> Visit the HBR Receiver Web Site with over 100 pictures of receivers and
>  construction notes...... via http://www.qsl.net/k5bcq/
>
> Retrieve reflector archived data via http://mailman.qth.net
>
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