[HBR] HB Receiver

[Byron Tatum]

OK Dan-
    You point out a surefire flaw in my design. I had not thought about 
birdies at this stage. I wanted to stay with the same frequency relationship 
in the R-25 { 3-6 MC tuning range, 1415 KC. IF} in order to get the 
designed-in tracking linearity. I plan to set the tuning cap back away from 
panel and make a homemade round tuning dial that will mount on the 3 gang 
tuning capacitor and to place this dial behind a window on front panel. Just 
a thought -- this would save on buying an expensive dial mechanism and allow 
me to use the tuning capacitor as originally done { dial and geared down 
mechanism}. I imagine I will need to leave only a couple of plates on the 
tuning cap. Later I will go out in shop and measure capacitance at 3.5 MC 
then measure it at 4.1 MC on the 3 gang capacitor, this should tell me 
approx. how much capacitance change I will need to tune the 600 KC range.
    That is good to hear that you have used the BFO coil with 6BE6. The 
6BE6's seem to do well in 2-B, but if there is significant advantages to 
using separate osc./mixer tubes I am open to suggestions.
    Thanks for info, CUL, Byron.
----- Original Message ----- 
From: <Hopperdhh at aol.com>
To: <hbr at mailman.qth.net>
Sent: Friday, August 04, 2006 7:18 PM
Subject: Re: [HBR] HB Receiver


>
>
>
> Byron,
>
> Seems like it should work.  The first thing that jumps out at me  is your
> choice of oscillator frequency.  There will be a big birdy at  3990! 
> (Three
> times 1330 is 3990.)  If you go to the high  side, this won't be a 
> problem.
>
> For what its worth, I have used the 85 kc BFO can with a 6BE6 product
> detector, and it worked fine using the grid coil for the cathode.  Can't 
> remember
> if I had to open it up to change anything or not.  Would like to  here if 
> the
> oscillator coil will work the same way with the 6BE6.  I have  always 
> wanted to
> try that.
>
> Dan Hopper
> K9WEK
>
>
> In a message dated 8/4/2006 6:46:52 P.M. Eastern Daylight Time,
> bjtatum at ev1.net writes:
>
> Hello  All-
> I have been thinking about a homebrew receiver design  and wanted to ask 
> for
> opinions. I don't believe I am the first to propose this  design and I saw 
> a
> HB receiver by a VK2 I believe that was similiar. Here it  is :
> 1. RF front end and first mixer -- A copy of sorts of  the Drake 2-B, 
> whereas
> the RF amplifier covers all bands of interest and the  first mixer 
> operates
> as another RF Amplifier on 80 meters, but as a frequency  converter for 
> bands
> above 80 meters.
> 2. Variable IF -- The  variable IF will cover 80 meters as in the Drake 
> 2-B.
> I plan to use the parts  from an R-25 ARC-5 set { a parts unit I 
> cannabilized}
> to tune from 3.5 to 4.1  MC. My thoughts are to use the OSC. and RF 
> sections
> of the tuning gang { after  pulling most of the plates} and fixed 
> capacitance
> across the OSC. and RF coils  { from R-25} in order to get this tuning 
> range,
> using a 6BE6 converter tube.  IF output to be 1415 KC as in R-25 receiver. 
> Was
> thinking about placing  back-to-back 1415 KC IF transformers at output of 
> the
> variable IF feeding into  one low gain stage at 1415 KC followed by 
> another
> IF transformer. { This is a  departure from Drake 2-B where 80 meter 
> variable
> IF is mixed down to 455  KC}
> 3. Third mixer -- The 1415 KC from IF amplifer would be  mixed down to 85 
> KC
> in a 6BE6 converter tube, using a L/C osc. at 1330 KC.{  Drake went in on 
> low
> side of 455 KC IF in the 2-B using 405 KC  osc.}.
> 4. Final IF Amplifier -- Plan to use the 85 KC IF  transformers from R-23
> ARC-5 set. Thinking that one stage of IF using 6BA6  will be sufficient.
> 5. BFO / Product Detector / AM Detector --  Plan to use 85 KC BFO coil 
> from
> R-23 receiver and have front panel BFO  control. Would like to have 
> selectable
> detectors and decent AGC, etc. probably  borrowing from HBR receiver 
> circuits.
> These are  some thoughts of mine. One question regarding the IF 
> transformers
> from the  ARC-5 sets : Some of them have taps on the coils, I noticed in
> schematics that  second IF transformer has a tap on input coil connected 
> to plate
> of first  stage tube and tap on output coil of transformer connected to 
> grid of
> second  amplifier tube. Are these taps to reduce the gain? When I use a
> higher gain  tube such as 6BA6 how should I connect these transformers?
> Thanks, Byron.
> ************************************
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>
>
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>
>
>
>
> ************************************
> Visit the HBR Receiver Web Site with over 100 pictures of receivers and
> construction notes...... via http://www.qsl.net/k5bcq/
> there is also a mirror (faster response)at http://k5bcq.edebris.com/
>
>
> Retrieve reflector archived data via 
> http://mailman.qth.net/mailman/listinfo/hbr
>
>
>