OzHam Vintage & Homebrew Ham Radio

Glen, VK2FC

Home

s-line.jpg (73611 bytes)    A Collins S/Line Station from the late 1950's plus a Collins 75A-4 receiver from the mid 50's.  This S/Line consists of a 75S-1 receiver, 32S-1 transmitter, 30L-1 linear amplifier, SM-3 dynamic desk microphone and a 302C-3 wattmeter. The Heathkit scope in the centre on the upper shelf is used as a modulation monitor. 

GDT.JPG (108509 bytes)   A Collins KWS-1 transmitter and 75A-4 receiver from the mid nineteen fifties.  This pair are affectionately know as the Gold Dust Twins.  I acquired the transmitter without the power supply and would like to purchase the Collins power supply so drop me an e-mail if you can help.  In the mean time I'll use a homebrew supply.

R-390A 002.jpg (161918 bytes)    A pair of Collins designed, Motorola built R-390A H.F. (shortwave) receivers.  Both working well but need a tidy up.

Drake 2B_1.jpg (103329 bytes)    A Drake 2B amateur band H.F. receiver awaiting restoration.  This old receiver is working well but needs a bit of a cosmetic tidy up.  It's planned to be used in conjunction with the homebrew AM transmitter below.

AM TX 001.jpg (134780 bytes)    AM TX 002.jpg (150855 bytes)    AM TX 004.jpg (157710 bytes)

This 40 metre AM transmitter uses a 6DQ6 tube in the PA stage producing around 15 watts of RF output and is modulated by a pair of 6L6 pentodes.  It struggles to achieve 100% modulation with a common H.T. supply but the new power supply should improve this.  Frequency control of the transmitter is determined by a plug-in crystal or an outboard homebrew DDS VFO. 

160.jpg (111537 bytes)    amp_front.jpg (40427 bytes)    amp_rear.jpg (55536 bytes)    amp_top1.jpg (89757 bytes)

amp_b1.jpg (38101 bytes)    amp_b2.jpg (50548 bytes)

The photos above are of VK2FC's homebrew single band (160 metre) amplifier.  The tube used is an Eimac 4-1000A tetrode in grounded grid configuration.  Maximum output power is around 1400 watts when driven with an exciter producing 120 watts.  This amp has proven to be very stable and reliable considering most of the R.F. components were acquired as 2nd hand.

813_linear_1.JPG (220632 bytes)    813_linear_psu.JPG (183929 bytes)    813_linear_top.JPG (194509 bytes)

813_linear_13.JPG (138330 bytes)    813_linear_bottom.JPG (250308 bytes)    813_linear_front.JPG (157163 bytes)

813_pa4.JPG (211831 bytes)    813_pa_glow.JPG (132050 bytes)

An experimental homebrew amplifier using a pair of 4-250A tetrodes.  Passive grid (50 ohm) produces 750 watts with 2700 volts on anodes.  Screen voltage is regulated by solid state circuitry.  This amplifier covers the 160, 80, 40, 20, 15, 10 metre bands.  I'll get around to painting it and labeling the panel one day!

Back

This page was last updated on Thursday, 15 November 2007