Lots of people have forgotton the Thunderbolt 305. one of the CLEANEST old sweep tube amps ever!
With it's compliment of 1 driving 3 6LQ6's, it was just a very simple, and well built amp. I picked one up at a yard sale in 2009 for 25 bucks. Still looked nice! Very dusty, and dirty from sitting in a garage for years I imagine. I brought it home, and brought it up on a Variac. Fan ran nicely, although a little noisey....even the meter light worked! So I immediately started the cleaning process. Removed the fan, the transformer, the tubes, and got to work. Needless to say after hours of intense cleaning, the inside of the chassis was clean enough to eat off of.
I cleaned and lubed the fan, wiped the tubes down, cleaned the transmit relay, replaced the transformer and the tubes, brought the chrome faceplate to a mirror like shine, and fired it up again.
She happily came back to life, and the fan could hardly be heard! I checked it out on a dummy load, and she was doing about 125 watts on low on AM, and about 200 or so on high with a 3 watt dead key from my Uniden Washington.
So I took it for a test run. Jumped up on 27.385 LSB during some good DX conditions, and she showed a nice 310 watts out with the 18 watts PEP from the Washington. I was in Florida, and grabbed a contact from the Black Hills in S. Dakota. Said I was coming in at 15 over 9, with slightly scratchy audio, but not enough to affect intellegibility. I continued the DXing for about an hour or so...until conditions started to fade.
Had some conversations with my locals, they said it had a great increase in signal strength, but on high the audio degraded slightly. Then I had an idividual pop on frequency and tell me I was running a "splattery" amp.
I immediately apologized, and proceeded to correct the problem, although it took a couple weeks waiting for some parts.
All I did was replace the three HV filter caps on the underside of the chassis....and put in 4 NOS 6LQ6's I ordered from an online tube store.
The NEXT time I fired it up....it was an entirely different story! The results:
430 watts PEP on SSB!! With AWESOME audio!
I had people in Washington State telling me to turn down the audio! I was extremely clear, but extremely loud!! And a contact in Seattle stated a 20 over 9 signal report, and though I was running Ham gear due to the quality of the audio! Which the microphone at the time was a hand held D104M6!!
The DX reports from that point on were consistently the same.....from all over the world!! And my locals were amazed at the audio quality in combination with the enormous signal increase.
I ran that amp for 6 years without a hitch untill one day a perimiter lightning strike destroyed all my equipment.
Yes.....I cried on that day....as the loss was far more than just the amp. But.....to this day that was my absolute FAVORITE amp of that class, and always will be. Anyone who has one and has not already done so....just do the simple replacements I did, and you will experience the joy I had I'm sure. Because if you already did.....then you know what I'm talking about!!
I'm now a ham, and run much different equipment, and much more expensive and higher quality equipment!! But the Thunderbolt 305 will always be one of my favorite memories.....and STILL IS one of my favorite amps.....of that class. So if youv'e got one......happy DXing!! Enjoy!! 73's!
With it's compliment of 1 driving 3 6LQ6's, it was just a very simple, and well built amp. I picked one up at a yard sale in 2009 for 25 bucks. Still looked nice! Very dusty, and dirty from sitting in a garage for years I imagine. I brought it home, and brought it up on a Variac. Fan ran nicely, although a little noisey....even the meter light worked! So I immediately started the cleaning process. Removed the fan, the transformer, the tubes, and got to work. Needless to say after hours of intense cleaning, the inside of the chassis was clean enough to eat off of.
I cleaned and lubed the fan, wiped the tubes down, cleaned the transmit relay, replaced the transformer and the tubes, brought the chrome faceplate to a mirror like shine, and fired it up again.
She happily came back to life, and the fan could hardly be heard! I checked it out on a dummy load, and she was doing about 125 watts on low on AM, and about 200 or so on high with a 3 watt dead key from my Uniden Washington.
So I took it for a test run. Jumped up on 27.385 LSB during some good DX conditions, and she showed a nice 310 watts out with the 18 watts PEP from the Washington. I was in Florida, and grabbed a contact from the Black Hills in S. Dakota. Said I was coming in at 15 over 9, with slightly scratchy audio, but not enough to affect intellegibility. I continued the DXing for about an hour or so...until conditions started to fade.
Had some conversations with my locals, they said it had a great increase in signal strength, but on high the audio degraded slightly. Then I had an idividual pop on frequency and tell me I was running a "splattery" amp.
I immediately apologized, and proceeded to correct the problem, although it took a couple weeks waiting for some parts.
All I did was replace the three HV filter caps on the underside of the chassis....and put in 4 NOS 6LQ6's I ordered from an online tube store.
The NEXT time I fired it up....it was an entirely different story! The results:
430 watts PEP on SSB!! With AWESOME audio!
I had people in Washington State telling me to turn down the audio! I was extremely clear, but extremely loud!! And a contact in Seattle stated a 20 over 9 signal report, and though I was running Ham gear due to the quality of the audio! Which the microphone at the time was a hand held D104M6!!
The DX reports from that point on were consistently the same.....from all over the world!! And my locals were amazed at the audio quality in combination with the enormous signal increase.
I ran that amp for 6 years without a hitch untill one day a perimiter lightning strike destroyed all my equipment.
Yes.....I cried on that day....as the loss was far more than just the amp. But.....to this day that was my absolute FAVORITE amp of that class, and always will be. Anyone who has one and has not already done so....just do the simple replacements I did, and you will experience the joy I had I'm sure. Because if you already did.....then you know what I'm talking about!!
I'm now a ham, and run much different equipment, and much more expensive and higher quality equipment!! But the Thunderbolt 305 will always be one of my favorite memories.....and STILL IS one of my favorite amps.....of that class. So if youv'e got one......happy DXing!! Enjoy!! 73's!
