bands, or even hopscotch bands that suit your particular
interests. Or, maybe just use the RF deck or sweep board
to adapt into different designs of your own.
RF loves surface-mount technology, so if you are into
this all the parts are available in SMD packages (of course,
the MMIC amplifier and varactor diode already are).
I have also included a schematic of a detector probe
back in Figure 2 that can be used to give an envelope
display rather than an RF presentation on the CRT.
However, it requires a high level of detection for good
linearity. Fair linearity can be obtained in the 100-1,000 mV
range. I did add ventilation holes in the enclosure so that
the unit reaches thermal equilibrium in a shorter time
period. Future plans call for an active detector probe so as
to drive the detector diode at a higher level for improved
The completed generator is shown with its own internal
frequency counter and prescaler, but these were omitted in
the internals picture of Figure 7 for clarity (although I kept
the optional supply in the power supply schematic).
Unfortunately, space does not permit for that construction
since it would be a complete article in itself. If there’s
enough interest, the editors may be open for a follow-up
article on the design and construction of that. NV
36 December 2013
T1 120V/24V c.t. 85 mA SB3512-2024 $4+
T2 120V/30V c.t. 55 mA SB3518-3030 $4+
T3 120V/18V c.t. 65 mA SB2812-2018 $3
MC1648 and MC100E 1648 datasheets are easily obtained
through Google and have a lot of good information. DIP
version available at www.elexp.com (Electronix Express).
Most major distributors carry the MC100EL1648.
MMIC-1 is available at www.minicircuits.com. Ordering can
be done directly. Also, lots of downloads for info.
MV1404-9* is available through Arrow Electronics. Datasheets
are on the Web.
Band switch S1 available at Mouser (Mouser# 105 prefix).
Also the line of Alpha pots are quite cheap here.
Coils L1-L10 and ferrite beads available at Mouser and
Tamura transformers T1, T2, T3 available at Mouser and
Digi-Key (Mouser #838 Prefix).
All catalog nos. are Mouser.
*MV1404 - 9 is subject to availability. If you have trouble,
I do stock this item.
Problems? Email me and I can walk you through most of the
construction and design. I have more supporting info that you
R2 390 ohm
R3 150 ohm
R5 220 ohm
R6 470 ohm
R7 120 ohm
R8 240 ohm
R9 43 ohm
R10, R11 200 ohm 1 watt $0.15
C1-C2, C4-C10, C12,
C14, C16, C18 0.1 mfd
C3, C17 0.01 mfd
C11 0.22 mfd
C13 0.47 mfd
C15 tantalum 4. 7 mfd
FB1 J. W. Miller FB43-226-RC $0.15
FB2 J. W. Miller FB43-287-RC $0.15
L1-L10 See text chart for values $0.2-$0.4
Conformally Coated, Fastron, or Xicon
U1 ( 14 DIP) MC1648 $7
U1 (alternate) MC100EL 1648 (SMD) $10
MMIC Mini Circuits GALI- 55 $3
Q2, Q3 2N3904
VD 1, 2 MV1404-9 (varactor diode)
RF Band Switch (S1) Alpha SR2921F-12S $4+
Alpha also carries a line of low priced potentiometers used in
All resistors are 1/4 watt 5% unless otherwise noted. *Asterisks denote 1/4W 1% metal film.
Sweep Generator Board:
R1, R3 22.1K
R4, R28 1.0 meg
R5, R17 2K
R6 910 ohm
R7, R10, R11,
R30, R31 10K
R8 820 ohm
R9 2. 4 meg
R12, R18, R24 1K
R13, R20 4.3K
R15, R23 3.0K
R21, R27, R29 51K
R26 150 ohm
R32 100 ohm
C1 -0.001 mfd
C2 1.0 mfd Not ceramic or 'lytic
C3 22 mfd 'lytic
C4 100 mfd 'lytic
C5, C7 4. 7 mfd tantalum
D1, D2 1N914
D3 10 mA LED red
D4 10 mA LED amber
IC1, IC2 TLO84