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3 tube am 75 meter mobile
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3 tube am 75 meter mobile
On Sun, 9 Dec 2007 07:15:04 -0800, W7CXA wrote:
I am looking for information on a 3 tube 75 meter am transmitter that was around about 1958. Two of the tubes were 6146, one for modulator and one for final. I cant remember what the oscillator was. I see nothing close to your description in the 1957 ARRL Handbook - in either the "Mobile Equipment" section, nor the "HF Transmitter" section. Or, are you referring to a piece of commercial gear? There was no osc. buffer, and no mic. preamp? (I did run across an ad for Burstein-Applebee. Now, _that_ *really* brings back memories! ) 73 Jonesy -- Marvin L Jones | jonz | W3DHJ | linux 38.24N 104.55W | @ config.com | Jonesy | OS/2 *** Killfiling google posts: http://jonz.net/ng.htm |
#3
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3 tube am 75 meter mobile
On Dec 9, 5:26 pm, Allodoxaphobia wrote:
On Sun, 9 Dec 2007 07:15:04 -0800, W7CXA wrote: I am looking for information on a 3 tube 75 meter am transmitter that was around about 1958. Two of the tubes were 6146, one for modulator and one for final. I cant remember what the oscillator was. I see nothing close to your description in the 1957 ARRL Handbook - in either the "Mobile Equipment" section, nor the "HF Transmitter" section. Or, are you referring to a piece of commercial gear? There was no osc. buffer, and no mic. preamp? (I did run across an ad for Burstein-Applebee. Now, _that_ *really* brings back memories! ) 73 Jonesy -- Marvin L Jones | jonz | W3DHJ | linux 38.24N 104.55W | @ config.com | Jonesy | OS/2 *** Killfiling google posts: http://jonz.net/ng.htm Yup, good memories... However, ARRL was not the sole source of info... I vaguely remember a quick-n-dirty mobile AM with 3 tubes... But, why worry about what was published then.. We can cobble up something similar today on our own... Use a VXO for the vfo oscillator to make it stable under modulation peaks... Use screen grid modulation... Won't need a 6146 for the modulator, a 12AX7 should do (I'd have to research that, so don't take it for gospel) OTOH, the nice nursey says I need to take my pills now... denny / k8do |
#4
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3 tube am 75 meter mobile
I do not remember a 3 tube transmitter using 2 6146 tubes. I question that
arrangement, because the 6146 modulator would be running class A and very inefficient. However, I am familiar with a 2 tube transmitter using a 6146 final. It was very effective and a lot of hams built one. It was called the "Golden Gate" circuit, because it was popular in San Francisco. Using1/2 of a 12AT7 for a crystal controlled oscillator, driving a 6146, it was screen modulated by the other 1/2 of the 12AT7. Used a carbon mike and step up transformer. It appeared in the "New" CQ Mobile Handbook, second edition - 1956. 73, Colin K7FM |
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3 tube am 75 meter mobile
It appeared in the "New" CQ Mobile Handbook, second edition - 1956. 73, Colin K7FM I said the memory was vague... But I believe you have described what I vaguely remembered... Yup, that should work... And it will work today, still... A VXO will give you a bit more flexibility fro todays crowded bands... denny / k8do |
#6
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3 tube am 75 meter mobile
And, remember that when you find an old carbon mike, rap it hard on the side
of the desk to shake up the carbon granules, that may have caked up sitting for decades. This is one mike that wants to be almost swallowed. Have fun. Colin K7FM |
#7
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3 tube am 75 meter mobile
On Dec 11, 9:36 am, "COLIN LAMB" wrote:
And, remember that when you find an old carbon mike, rap it hard on the side of the desk to shake up the carbon granules, that may have caked up sitting for decades. This is one mike that wants to be almost swallowed. Have fun. Colin K7FM Of course it has to be in transmit while you loosen the granules so that there is good current flow through the granules... denny / k8do |
#8
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3 tube am 75 meter mobile
On Dec 9 2007, 7:15 am, "W7CXA" wrote:
I am looking for information on a 3 tube 75 meter am transmitter that was around about 1958. Two of the tubes were 6146, one for modulator and one for final. I cant remember what the oscillator was. J. Andy Thompson W7CXA Yakima, WA Back in the 50's there was a very popular TWO tube mobile transmitter used by several mobile operators on 3995... Developed by Bob Carter, W6NTU who lived up on the side of Mt. Hamilton near San Jose... It used a12AT7 driving a sweep tube... Several of the fellows in addition to a variant of sweep tubes, used a 6146 and an occasional 2E26 in the final as well depending on available plate voltage... Half of the 12AT7 was the Oscillator, the other half was modulator... Carter Modulation transmitters were very popular due to their simplicity and performance. When loaded a bit on the heavy side, the audio sounded quite good... Go to: http://www.geocities.com/ResearchTri...13/carter.html For a bit of History and a schematic of the transmitter... Remember load that lil sucker fairly heavy with very little perceptible plate dip for best audio results... Good Luck de Grady K6IXA |
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