Tube Power

1
EN37ed North Of The Tropo Line
2
Looking At EN34
3
Tube Power

• Could/Should You Build a Tube Amplifier?

4
Why KØAWU BuildsAmplifiers

• Availability of options (1960-1970s)
• Limited Antenna options, SO Power
• Junk Box Deeper than Wallet
• Repair-ability
• Enjoy building
• Pride of non-factory gear
• Have to I be heard in that EN34 QRM!

5
Amplifier Racks - 4/03
6
4CX250 Family
4CS250R
4CX250B
8560A
7
Looks Simple Enough
8
KØAWU 2 meter Amplifier Built in 1967
4CX250B --- RF Deck only
9
Different Looks
222 Mhz Cavity
10
Lots less Copper (and a Coil!)
6M amplifier
8560A Conduction Cooled
Construction Photo
11
432Mhz -- Grid/Socket
12
K2RIW Amplifiers 1971
13
Big Power - 6M 8877
14
Complexity / Disadvantages 4CX250B Example
15
Power Supplies
16
(No Transcript)
17
Why Should You Consider a Tube Amplifier?
18
Could You? Sure!Should You? Only you know.

• It would be Rewarding!!
• It would be Educational.
• It would be FUN!
• IT could add an entirely new dimension to your
  hobby.

19
Hand Tools and Common Test Equipment are all
thats needed
20
Cost Leaders
21
Multiple RF Decks A Common Power Supply?

• Common HV, Screen supply
• Then RF decks only need to be built.
• Filament and Bias on each RF Deck
• Challenge -- Switching of Amplifiers
• Portability Reduced
• Common Failure Mode

22
Modular Build Approach -- Build / Test by Module
--
23
Cautions
24

• (a) Motorola conduction cooled amps (8560AS)
• (b) Quintron ... (4CS250R costly tube)
• (c) GE Master Pro amplifiers
• (d) FAA - (1) Collins TV36/35- series
• (2) AM6155 Fair Radio
• (3) AM178 (Cathode driven)

25
Construction Articles For Reference

• --- Use For A Guide And Ideas Design from
  there ---
• (1) ARRL Handbooks late 1950 - 1970's
  
• (2) QST, Ham Radio, 73 magazines from same
  era
• (3) RSGB Handbooks
• (4) Internet

26
URLs and Magazine Articles

• (2m 4CX250B stripline) http//home.attbi.com/w
  1wv/ham/amp.htm
• (Good index of amplifier articles)
  http//w1.875.telia.com/u87509509/2mpa.htm
• (GS35B 2m and 432 Amps) http//www.qsl.net/dl4mea
  /2g35.htm
• (ND2X -- QRO Via Russian Tube Index)
  http//www.nd2x.net/base-1.html
• (Eimac Data sheets) http//www.david-kirkby.co.u
  k/ham/data/
• (Surplus AM-912 144/222) http//www.n1bug.net/te
  ch/am912.html
• 432 Mhz 4CX250B amp Radio Handbook W6SAI 18th
  Edition 1970 Pg 680
• --- Amplifier designs in use at K0AWU ---
• 6 meter amp --- 1978 4CX250B ARRL Handbook Pg
  232
• 2 meter 4CX250B "Plumber Amp" ---- October 1956
  QST Pg 40
• 2 meter W6PO 8877 amplifier http//web.wt.net/
  w5un/8877-1.htm
• 222 Mhz 4CX250B amp --- 1971 ARRL Handbook Pg 440
• 432 Mhz 4CX250B amp --- 1968 ARRL VHF Manual Pg
  257
• 1296 Mhz 7289/2C39 N6CA amp 1985 March April
  QST

27
1296 Mhz --- Where?
Machined cavity
N6CA Design 7289/ 2C39
25-30 watts Out With 3 watts drive
28
VE4MA Creation