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Re: Tuned input
Wasn't there a 7 call ham that made such a board? Think he also made high voltage boards.
By mike repinski · #39914 ·
Re: Tuned input
I suppose the answer to that would be to disconnect power to the tuner after it's done its job.... Or rewire it so it only tunes when power is applied, then you remove power to keep it from
By Steve · #39913 ·
Re: Tuned input
The amplifier version of the AT100 tuner has different stuff programmed into the PIC chip. 73, Alek VK6APK
By Alek Petkovic · #39912 ·
Re: Tuned input
I just bought two of them for $5 each at a local radio club auction, configured as coax-fed remote antenna tuners (RT-100 and RC-100, no longer sold) intended to be mounted at the antenna, complete
By Steve · #39911 ·
Re: Tuned input
They stopped making that unit years ago. I tried using the at100 remote ldg. It decided to tune while I was transmitting. That was it. Smoked. C
By W7WRX · #39910 ·
Re: Tuned input
Hi Tuner-Seeker W7WRX! I believe that LDG makes a board-size tuner just for amp builders. 7 Band, 9 Band, I'm not sure. But they advertise in QST. They've been doing that for years. Happy New Year
By HaL Mandel · #39909 ·
Tuned input
I am thinking of adding a tuned input to one of my amps.? Does anyone make a board?? I searched around and there seems to be nothing available. Does anyone have a board laying around?? Maybe from
By W7WRX · #39908 ·
30L-1 ALC
What negative voltage ranges should a find in this amplifier¡¯s ALC circuitry? I know it depends on the setting of the pot. Just curious about what variation I should see. Richard WB5NEN
By Richard P · #39907 ·
Re: Building my first amplifier. Where to start?
Just check the FU-81(GU-81M) amplifier, the screen grid current is 260mA for two tubes.so I guess 130mA per tube.Don't believe the rumors that the GU-81M won't work at 21MHz and above. This is
By Hsu · #39906 ·
Re: Building my first amplifier. Where to start?
Hsu, Thanks for the details on the gu81m tubes. They look great too. Too pretty to be hidden. I have settled now on two gu43b tubes. Should be happy at 2kw and push to 3kw if needed.
By desmond auld GI0UTE · #39905 ·
Re: Building my first amplifier. Where to start?
Hal, When I got the transformer I did some experimenting, as you do :) . I found that if I run the outer two phases in parallel ( with one reverse polarity from memory, tbc) I could also parallel the
By desmond auld GI0UTE · #39904 ·
Re: Building my first amplifier. Where to start?
Jeff, I have parked the idea of the triode and have ordered the tetrode boards from Dom, f1frv who has been very helpful. I am also finalising an order with Alex Ur4LL, for some gu43b tubes,
By desmond auld GI0UTE · #39903 ·
Re: Gi46b on 2m - Thermal drift problem
Negatory. Being HFers, we can be forgiven, perhaps, for forgetting that at V/UHF, things are different... and there are such things as "transmission lines". This is a traditional stripline plate tank,
By Steve · #39902 ·
Re: Gi46b on 2m - Thermal drift problem
Watch out.? You will introduce a ton of stray C on that hb teflon? plate block cap assy.....to the chassis below it. That amounts to a bunch more anode to chassis C. Knowing the spacing, and the
By Jim VE7RF · #39901 ·
Re: Gi46b on 2m - Thermal drift problem
Insert a teflon sheet or other suitable insulator between 2 copper slabs, one of which is directly on the anode. Here is mine to give an idea. It's based on plans published by YU1AW. (Ignore the
By va3dxv · #39900 ·
Re: Gi46b on 2m - Thermal drift problem
Yes, similar to a K2RIW amp.
By mike repinski · #39899 ·
Re: Gi46b on 2m - Thermal drift problem
An even better option, if your tank is well insulated (as mine is) is to remove the blocking cap entirely How can this be done?
By mike repinski · #39898 ·
GS35B 2m amp
Tim and anyone interested : Here¡¯s looking inside the RF box. You can see the original blocking cap - just like yours ! This is a YU1AW ¡°Lazy Builder¡± design. Suited my construction capabilities
By John Sparkes · #39897 ·
Stuffed blocking cap
Tim - here¡¯s what happened to my 2200pF blocking cap. Cracked and a little burnt. This caused ALL of the ¡°thermal¡± power output drift in my 2m amp. She¡¯s rock solid now, for complete JT65B
By John Sparkes · #39896 ·
Re: Gi46b on 2m - Thermal drift problem
No probs. An even better option, if your tank is well insulated (as mine is) is to remove the blocking cap entirely and connect the anode directly to the tank. I used large Teflon standoff posts and
By John Sparkes · #39895 ·