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Re: 144 mhz tuned input for a GG YC-156 ??
Yes, that's 2 1/2 times the value for a 8877 that works good up to 222. Will this tube go that high?
On Friday, January 5, 2024 at 02:51:29 PM EST, Jim VE7RF <jim.thom@...> wrote:
Ok, how does one go about building a tuned input for a 144 mhz amp, using a YC-156 tube ?? This is for a cathode driven? ?YC-156 ? ( The 1/2 wave tank for the output side is fine, and tunes up fine, with calculated RL.... to the 50 ohm output.)? The output is not the issue, it's the input.? ? What options, if any, do we have ?? ?What's the fix ? |
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144 mhz tuned input for a GG YC-156 ??
Ok, how does one go about building a tuned input for a 144 mhz amp, using a YC-156 tube ?? This is for a cathode driven? ?YC-156 ? ( The 1/2 wave tank for the output side is fine, and tunes up fine, with calculated RL.... to the 50 ohm output.)? The output is not the issue, it's the input.? ? What options, if any, do we have ?? ?What's the fix ? |
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Re: HomeBrew Amp Chassis
KB1SEL got the premade chassis and cabinet from ICA manufacturing in? NJ.? They come completely pre-fabricated and ship flat. All you do is assemble with machine screws. On most of em, they have the outer front panel, and also a 2nd front panel inboard from the outer panel. Stuff like vac caps, verniers etc, is between the 2 x panels.... if you want.? The pre-made cabinets come in every dimension you can think of.? ?Shipped in the flat pack, the shipping is cheap.? ?ICA runs flat out 6 x days a week.? That's also where the .515" thick teflon chimney for the 10 kw 6m, 3x6 amp came from.? ICA ManufacturingP.O. Box 677 Chargercharger@... |
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Re: HomeBrew Amp Chassis
¿ªÔÆÌåÓýKeep in mind that sometimes, paying somewhat more for the chassis can make up for a lower shipping cost, too. Compromise, compromise, compromise... Steve, K0XP
On 1/4/2024 1:52 PM, mike repinski via
groups.io wrote:
--
See my QRZ.com page at |
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Re: HomeBrew Amp Chassis
The Amp Repair guy has a few videos on Utube constructing a few amps. He purchase his chassis ready made. Check Utube for the name of the supplier. And yes there are metal suppliers listed on the web. You need to find a local one to save on shipping.
On Thursday, January 4, 2024 at 04:49:04 PM EST, Tim Fern <timjfern@...> wrote:
My little local town has Al. supplier who will guillotine pieces to size for free If the order is over ?10.... I expect most towns will have similar. I never bend pieces (although my Al. supplier can do that too for a small charge), I just cut angle-ally pieces and drill / tap M4 holes. 18 or 20swg for tank circuits, 3mm (10?swg) for chassis/front panels. best 73 |
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Re: HomeBrew Amp Chassis
My little local town has Al. supplier who will guillotine pieces to size for free If the order is over ?10.... I expect most towns will have similar.
I never bend pieces (although my Al. supplier can do that too for a small charge), I just cut angle-ally pieces and drill / tap M4 holes. 18 or 20swg for tank circuits, 3mm (10?swg) for chassis/front panels. best 73 |
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HomeBrew Amp Chassis
What's good choice for obtaining Aluminum plate, Aluminum Chassis..?? I'm searching ebay, lots of picks.? Others? Short story, About to cannibalize old amp for chassis but think NEW would turn out better on this one. I can assemble Aluminum, bend - not so much. Thickness?? 73 Robert W5AJ |
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Re: Gi46b on 2m - Thermal drift problem
¿ªÔÆÌåÓý4x HT50 or 55 do well on 2m with 4CX1000/3CX1500A7 amps. GI7b and similar tubes drift when cooling is insufficient. ? 73 Peter ? ? ? -----Original-Nachricht----- Betreff: Re: [ham-amplifiers] Gi46b on 2m - Thermal drift problem Datum: 2024-01-04T17:29:29+0100 Von: "Jim VE7RF" <jim.thom@...> ? ? ? ? ? For the OP, does that plate block cap even look like a cap at? 144 mhz ??? ?Will it handle the calculated rf current flowing through it at 144 mhz ?? John Lyles,? K5PRO helped myself and Scott out on that 10 kw 6m amp.? ?John used his test gear during a 3 way phone conversation, and was testing various HEC / centralab caps, like the 200 pf? and also? 500 pf variety, in both HT-50/58 size, and also HT-57 sizes.? On some of them, the SRF freq (self res freq)? was as low as just 42-45 mhz.? If 3 x caps were in parallel, SRF rose to 62 mhz.? On the HT-57 caps, in 200 pf size, SRF was 60 mhz...and? even higher, when paralleled.? Above the SRF freq, the cap looks inductive.? ?It's straightforward? test process to find the SRF freq for a given combo of single, or multiple caps in parallel.? |
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Re: Gi46b on 2m - Thermal drift problem
For the OP, does that plate block cap even look like a cap at? 144 mhz ??? ?Will it handle the calculated rf current flowing through it at 144 mhz ?? John Lyles,? K5PRO helped myself and Scott out on that 10 kw 6m amp.? ?John used his test gear during a 3 way phone conversation, and was testing various HEC / centralab caps, like the 200 pf? and also? 500 pf variety, in both HT-50/58 size, and also HT-57 sizes.? On some of them, the SRF freq (self res freq)? was as low as just 42-45 mhz.? If 3 x caps were in parallel, SRF rose to 62 mhz.? On the HT-57 caps, in 200 pf size, SRF was 60 mhz...and? even higher, when paralleled.? Above the SRF freq, the cap looks inductive.? ?It's straightforward? test process to find the SRF freq for a given combo of single, or multiple caps in parallel.? |
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Re: Gi46b on 2m - Thermal drift problem -Sorted
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On 3 Jan 2024, at 05:29, Tim Fern <timjfern@...> wrote:
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KW1000 amp renovation, filaments, bias and neutralization.
I recently acquired a British KW1000 linear which uses a pair of 572Bs and is somewhat similar to the SB200. The power transformer was missing but I have been able to fit a replacement from the junk box, it has 2 x 6.3 volt 4 Amp winding with no centre tap so am thinking of connecting the filaments in series. The first problem with this is one tube light up brighter and had 7 volts, the other 5 volts (these were old tubes, one Centron, the other Taylor). When I tried a newer matched pair from Penta the voltages were quite close.
Looking at the schematic for my TL922A I see the CT is connected to the linked filament pins via a 80 uH choke where the drive appears to be applied, although there is also a 0.01 uf capacitor whose purpose is unclear to me, across to one side of the main choke (22 uH). Any advice would be appreciated, also is any bias required in tx and is there a need for neutralization? - am directly grounding the grids. The KW1000 has a few additional turns on the filament choke which goes to a flat plate about 1" square and close to one of the tubes. Mike VK2AMF / G3XEF. Mike Fleetwood Canberra Australia and Sidcup UK. Worldwide email address is: mfleetwood@... |
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Re: Gi46b on 2m - Thermal drift problem
On Wed, Dec 27, 2023 at 11:30 PM, Steve wrote:
the impedance of the original stripline line is no longer maintained because of the additional thickness of that humungously-thick sheet of teflon being used between the two very-thick copper plates, which thickness looks like it has been vastly increased from the original dimensions.I'm not sure if this is in reference to my picture or not, but if so the camera may be playing tricks on you. The teflon I'm using is .4mm thick (in fact it's not even teflon in that mock up, it's a sheet of paper). The copper is only 1.2mm thick (except the bent support bracket, it is slightly over 2mm). Both fall within what was specified in the design I used (which, to be fair, I have no knowledge of its effectiveness... but hey I wanted to try, this is how we learn). Anyways I didn't mean to hijack the thread. Your notes about the dimensions of the cover are appreciated. I plan on making the enclosure soon! Happy new year to all! |
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Re: Tuned input
I see a quantity on Ebay but they are a small fortune. Not what I expected.
On Tuesday, January 2, 2024 at 12:37:28 PM EST, W7WRX <clark@...> wrote:
Mike.? I ordered the board from Fred at FAR.? He did not have relays or the trimmers. I found the relays and have ordered them.?? |
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Re: Tuned input
Arco was the big name in variable caps at one time. Not sure if they are still around. I wonder if there are any articles on that board? I see the original designer has passed. Mike
On Tuesday, January 2, 2024 at 12:37:28 PM EST, W7WRX <clark@...> wrote:
Mike.? I ordered the board from Fred at FAR.? He did not have relays or the trimmers. I found the relays and have ordered them.?? |
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Re: Tuned input
Mike.? I ordered the board from Fred at FAR.? He did not have relays or the trimmers. I found the relays and have ordered them.?? |
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Re: AL-80B fan
You guy's guess was about right! No beer but "fireball"! Bob W4JFA? On Fri, Dec 29, 2023, 8:45 PM Steve <k0xp@...> wrote:
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Re: Tuned input
¿ªÔÆÌåÓý
I have tried this in the past. It's a huge KLUDGE and would not recommend it.? That tuner is going to try to tune while you are transmitting, You're constantly showing your radio a bad match every time you change frequency as it has to retune.?
Unless you can somehow make it stop with hard ware or software it never works.??
The old LDG amplifier version had special code that made it work for an amplifier and it had board changes as we only need a small change to work with cathode drive.
Then, The biggest issue, Is the Q is never correct.? The Q is important here for properly function and flywheel effect.? The antenna tuner is never going to match the correct Q.? It's super narrow and will have to retune even with slight changes in frequency.?
If you jump from 14.100 to 14.250 its gonna ratchet away as you try to make a contact OR if its disabled, the SWR on the input will be 6 to 1.
What people end up doing is to remove the AUTO portion and just hard wire the relays for each band.? At that point, Just build a board and tune it.
C
From: [email protected] <[email protected]> on behalf of Brian Moran via groups.io <brian.moran@...>
Sent: Sunday, December 31, 2023 7:17 PM To: [email protected] <[email protected]> Subject: Re: [ham-amplifiers] Tuned input ?
Yes, you would mount the tuner inside your amplifier somewhere; the output of the input network should be close to the tube. Controls for the tuner, and potentially the display, would be on the front panel. ? |
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Re: Tuned input
Yes, you would mount the tuner inside your amplifier somewhere; the output of the input network should be close to the tube. Controls for the tuner, and potentially the display, would be on the front panel. ? |
Robert, W5AJ
Bob