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i am interested in getting someone to modify my amp so that it can use the russian tubes it is a Dentron GLA 1000 amplifier can contact me at email@example.com or florida 9548947602 or 9543948601
The GLA1000 uses sweep tubes, and the plate voltage is rather low ≈1kV. I don't know of any Russian tube that would correctly work in their place.
01-09-2011, 12:38 PM
I have a GLA 1000 also in stock. It's working but the tubes are also not so good anymore. I am interested in any replacement project for this amp at a low cost profile. It's easy to travel.
01-09-2011, 04:44 PM
Easy to do and all info is on N8GPQ website. I just did one. Dennis KD8LMM
01-09-2011, 06:31 PM
01-09-2011, 09:33 PM
The GI-7b tubes are getting scarce. However, the GI-7bT version are still plentiful. The only difference is that the GI-7bT version is larger in diameter and is supposedly "ruggedized" for "tropical" applications.
The operating specifications are identical between the 2 tube types.
Ted, N8GPQ does NOT perform GLA-1000 amplifier conversions.
While you may contact him regarding inquiries of his Russian GI-7b triode tube conversion, be respectful.
He was not oblgated to post his work, knowledge or craftsmanship!
Lawson, W4EMF has made the same request -- regarding his 2002 GLA-1000 conversion and photos.
Tony King, W4ZT (sk) who provides sockets for these tubes passed away in February 2009.
W4POZ is still offering these sockets for a limited time -- You should not expect them to be available (off the shelf) at a future date!
Russian GI-7b ceramic triode information and web links
Good luck with your conversion.
01-10-2011, 04:26 AM
Direct link to the N8GPQ conversion site:
01-10-2011, 01:13 PM
I believe it was Svetlana's website used to have a conversion using their EL509 Russian sweepie, believed to be the last one still 'in production'. Perhaps it is still 'up'. I have not attempted this conversion, preferring the 1984 cathode bias modification described in Ham Radio Magazine for that year, and the use of old 6LQ6/6JE6/6ME6 from junk color television sets. What can I say, it works and the price is right.
That big Russian tube sounds like overkill to me with the stock power supply. Maybe save those for 3-500Z replacements in SB-220 and L-4 series amplifiers.
HV on my mostly stock GLA-1000 runs around 1100 VDC for 120 VAC input. Kinda nasty for sweepies designed to top out at an Ep of 990 VDC and operate in harmonic-rich 15.75 kHz horizontal oscillator TV circuits but that's the way Denny Dentron designed it. My amp is good for ~350 Watts p.e.p. output in s.s.b. service. No tuned input either. I drive it with an IC-737 using it's internal automatic antenna tuner to match the amp's input circuit.
For all of the maligning these amps received, I've found this one to be a reliable, quality product, and it has to be at least 30 years old. The original manual is dated 1978.
GLA-1000 Internet Resources
Includes notes on Ham Radio magazine artcile noted by W3DBB
ZIP file of notes
GLA-1000 series (Plain, B and C models)
GLA-1000 Power Supply Upgrade
The Heathkit Shop, WB8VGE
Three (3) PC boards for Eastern European EL-509 sweep tube conversion
Two (2) PC baords for Russian GI-7b ceramic triode tube conversion
Dentron GLA-1000 by Bill Smith, KO4NR
UPGRADES AND MODIFICATIONS FOR DENTRON GLA-1000 SERIES AMPLIFIERS
Jim, K5LAD -- Former owner of Derrick Electronics (Oklahoma) and Dentron distributor/dealer
FAR Circuits also had PC boards to ADD the Tuned Input function to earlier GLA-1000 amplifiers.
PA0FRI modifications to Dentron GLA-1000
BAMA - GLA-1000 Manuals