Crystek Crystals Corporation
VCO (voltage-controlled oscillator) & PLL (phase-locked loop) modules for commercial RF and wireless applications including test and measurement equipment, telecommunications, sat comm, broadband transmission systems, wimax, base stations & more.
http://www.crystek.com

Lemos International
Manufacturer of low-power-radio-modules, data links, ovenized oscillators and crystal oscillators for RF applications.
http://www.lemosint.com/aol.htm

Oscilent Corporation
SAW Filter - Oscilent is a manufacturer of SAW Devices, IF SAW and RF SAW. Supplier worldwide of Crystal Oscillator, Quartz Crystal, Ceramic Resonator, TCXO, VCXO, Crystal Filter and Ceramic Filter products.
http://www.oscilent.com

HM International
Leading manufacturer of Frequency Control Products, including quartz crystals, oscillators, VCXOs, TCXOs, VCTCXOs, OCXOs, MIL/QPL oscillators, ceramic resonators, filters, monitor blancs and STRATUM 3 synchronization modules
http://www.hminternational.be

Seoan Electronics Co., Ltd.
Manufacturer of quartz crystal and crystal oscillators including TCXOs, VCXOs, and high frequency ECL oscillators. From Korea.
http://www.seoan.com/

Pletronics, Inc.
Manufacturer of crystals (for microprocessors and communication equipment), crystal filters, and crystal oscillators (clock oscillators, VCXO, TCXO, and TCVCXO).
http://www.pletronics.com/

ValpeyFisher
Crystals, clocks, oscillators, electronic quartz crystals, oscillators and filters, crystal-based timing devices, Matec, electronics, semiconductors.
http://www.valpeyfisher.com/

P&Y Crystal Industrial Ltd.
A manufacturer of quartz crystals includes ceramic filers, ceramic resonators, crystal oscillators, SMD oscillators, SAW resonators, SAW filters.
http://www.pycrystal.com

RFX Ltd
RFX Ltd UK Manufacturers of high specification Quartz Crystal Oscillators
http://www.rfx.co.uk/index.html

Citizen America Corporation
Manufacturing crystals and oscillators.
http://www.citizencrystal.com/