[Boatanchors] Pictures of my Homebrewed LF Regen receiver

[Ed via Boatanchors]

Nice construction Phil!
 
Ed#
 
 
In a message dated 9/12/2015 11:22:18 P.M. US Mountain Standard Time,  
ko6bb1 at gmail.com writes:

I'm not  sure if I posted this link to this mail list or not.  It's a zip 
file  of pictures I took after I completed building my homebrewed LF (low  
frequency, 150-530KCs in two ranges) Regenerative receiver.

I  wanted to get a "tube radio" again and decided to build my own. I'm 
too  old to handle the REALLY HEAVY iron like SP-600's and R-390A's.

It has  5 tubes + silicon bridge rectifier, but is actually a 7 tube + 
rect  circuit as two tubes are double triodes.  The tube line-up is. .  .
6AK5 Grounded Grid RF Amp, 1/2 12AU7 Armstrong detector, 1/2 12AU7  
cathode follower coupled to the plate of the detector to provide an  
output for an external frequency counter (the counter is the blue  
display on the shelf above the set), 1/2 12AT7 First audio amp/AF filter  
driver, 1/2 12AT7 post filter AF amp, 6AQ5 audio output, 0B2 105 Volt  
regulator for detector & RF amp.

The audio filter section has 6  bandwidths, "Wide", 400Hz CF, 600Hz CF, 
1020Hz CF, Low-Pass 1 &  Low-Pass 2.  The three BP filters each uses a 
separate 10H adjustable  AF choke that is tapped part-way up from 
ground.  Each is resonated  by it's own capacitor, and each is fed 
through a 27K resistor to the  tap.  Output from the filters is via a 
270K resistor to the high side  of the volume control, then the 
"Post-filter" AF amp.  The isolating  resistors are there to keep the "Q" 
and selectivity of the tuned circuits  high.

It is entirely a "retro" receiver with technology that was  available in 
the 1930's, except I used a silicon bridge rectifier simply  because I 
didn't feel the power Xformer could handle the filaments of a  6X4 tube, 
and besides I wanted full wave rectification as it's easier to  
effectively filter 120CPs.  Most of the circuitry is entirely my own  
design, though I can't lay claim to anything that hasn't been done  
before, circuit wise.

The output for the frequency counter is  entirely a convenience function 
to simplify calibration of the National  reduction drive, it doesn't add 
anything to the DX performance of the  set.

So far the set is performing far better than I expected a regen to  do, 
especially in the tough NDB band where signals are weak, the band is  
noisy, and summertime is NOT the best time to chase beacons!  Over 60  
NDBs have been heard on it in the past couple weeks, from Hawaii to  
Puerto Rico, Canada to Mexico. . .

Here's the pictures (you DON'T  need a Box account to download the zip 
file).
https://app.box.com/s/60cemuh38aaz0f5gra0egclf4ph0lnpg

-- 
73 de  Phil,  KO6BB
http://www.qsl.net/ko6bb/  (Web Page)

PRESENT  RADIOS:
Grundigs:    S-350 (~2006), G6 (2011) & S450DLX  (2014).
HOMEBREW:    7 Tube+Rect Regenerative RX for LF (built  2015)
Icom:        R-75 With Cascaded 250 & 125Hz  CW Filters. (~2005)
Icom:        IC-7200 Transceiver  (~2015).
Radio Shack: DX-380 digital portable (~1990).
Zenith:   Royal-7000 Transoceanic Portable (~1968).

ACCESSORIES:  HOMEBREW LF-MF Pre-Amp, MFJ-993B HF Auto-Tuner.
HOMEBREW 8 Hz Audio Filter.

ANTENNAS:  88  foot Long Ladder-line fed dipole at 35 feet AGL for MW/SW.
HOMEBREW Active Mini-Whip at 36 Feet AGL for  LF/MW/SW.
HOMEBREW 37 foot "Low  Noise Vertical" at 11 feet AGL for LF/MW/SW.

Merced, Central  California, 37, 18, 37N   120, 30, 6W  CM97rh

______________________________________________________________
Boatanchors  mailing list
Home:  http://mailman.qth.net/mailman/listinfo/boatanchors
Help:  http://mailman.qth.net/mmfaq.htm
Post:  mailto:Boatanchors at mailman.qth.net

List Administrator: Duane Fischer,  W8DBF
** For Assistance: dfischer at usol.com **


This list  hosted by: http://www.qsl.net
Please help support this email list:  http://www.qsl.net/donate.html
Message delivered to  couryhouse at aol.com