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Yes, it's a possibility that those capacitors are bad but more likely is that the 80m and/or 160m contacts on the band switch have been burnt away. It is quite common on the 2100Z. Shine a light down into the band switch and check every contact carefully. From memory, it is not easy to pick the burnt contacts at first glance. I can add that it is not a fun job to change the switch. I have done a couple over the years and I'm not keen to do it again. 73 and good luck, Alek VK6APK On 9/08/2024 3:44 pm, vk3acu@... wrote:

Please reply to this message and include an attachment. I don't want to have a discussion here or for this thread to get out of control so please just say hi, attach a picture, and that's it.

Hi all, I'm in the beginning of planning on replacing the slow mechanical TR switches/relays in my 2K-3. Looking at the schematic it appears pretty straight forward. 12v to each relay. I have three questions about this... 1. Does anyone have an opinion on which vacuum relays to use? 2. How do I sequence them? 3. Ideas on physically mounting them. Any opinions would be appreciated. Thank You very much. Bob W4JFA

Robin, Here is a problem that may be similar to yours: https://www.eham.net/forum/view?id=topic,112624.0.html I had the shorted Q2 problem as well in my Centurion. 73 Bill N4LG PS: Another problem is a wonky mode switch. I had to make a modification to my Centurion logic to fix a "state" problem. See attached.

I'd like to query the collective knowledge about a Ten-Tec Centurion amplifier I've been working on, if you'd be so kind as to respond: I found that one tube had a cathode to grid short. I ordered and received a new pair of 3-500ZG tubes from Tom at CTR Engineering. I installed the tubes and it makes power. With the amp keyed into a dummy load & no drive, I see an indicated plate current of ~125mA, which I think is normal for a pair of 3-500Z tubes in grounded grid; please comment on that. More to the point, the bases of the tube plates glow a dull red in that condition. I've been told by an elmer who I'm inclined to trust that the plates shouldn't glow with only 125mA plate current, and if they are glowing in keyed/idle, then the indicated plate current is likely false & for some reason greater than 125mA. The original fault that I found is one tube has a short between grid and cathode, the other tube doesn't show any shorts. Is it possible or likely that some of the resistors used to derive the plate current indication were damaged by the shorted grid/cathode condition? If the plate current is greater than 125mA, what would cause that? I'm aware that Ten-Tec had some problems with bias from the QSK board in these amps for a time, but I don't know anything more about that. Any info is appreciated. I recorded these parameters on each band; measurements taken from the front panel meters of the amp. I stopped at 1kW output because I don't have a slug for my Bird 43 that will indicate above 1kW on HF frequencies. Band Load Tune Pin Pout Iplate ma Igrid ma 160 10 8 80 1kW 600 180 80 10 5 55 1kW 630 140 40 10 2.5 80 1kW 440 160 30 (40) 1.6 0.75 50 1kW 450 160 20 6 0.75 50 1kW 500 170 17 (15) 7.4 1.25 60 1kW 630 160 15 6 0.75 80 1kW 530 160 10 5 0.5 75 1kW 600 160

Peripherally related... I have a new-to-me Bird 8890 load. It's rated VSWR 1.1:1 to 1 GHz, but sweeps substantially worse, rising to nearly 3:1 at 435 MHz. I've taken the load assembly out of the oil and there's no obvious physical damage. The load does test 50.02 ohms at DC. Any suggestions on what to try in order to get this bad boy back online? Thanks,

First time I ever set foot in an SB-200 and it doesn’t look too complicated. But I want to make sure I have it squared away before returning to its owner. My buddy bought this for $200. It looks clean inside with a pair of Cetron 572Bs that don’t look like they had any abuse. As a matter of this thing looks pristine inside. They did place a Harbach ‘Soft Key’ and the all the filter caps have been replaced with CD’s. The parasitics don’t look as though they suffered any kind of excessive heat. Here is where it gets interesting: It seems the previous owner said that R15 was always cooking. Lo and behold sure enough the 1.5Ω resistor is fried. Following the lead up into the base of the 572Bs, I see where somebody replaced one of the 1W 33Ω resistors with what appears to be either a ? watt or ? watt going to the grid. The other has the original carbon comp 1W there. Also, the where the wire connects to the terminal strip, it was cold soldered and moved around freely making continuity intermittently. So 2 questions: 1) would that intermittent cause that meter shunt R15, to toast like that and 2) do those resistors for the grids have to be 1W or will ? suffice like what is in there? Also, could it be possible it is suffering from a spike as a result of the relay coil? (ok 3 questions!). Included is a photo. If it turns out this is all that is wrong with it, my friend scored the deal of the day at $200! Mod-U-Lator, Mike(y)/W3SLK PS: I also included a photo where that green wire from R15 comes and the different grid resistors.

A friend sent me this sheet. I thought I would post it in case anyone needs it at a later date. This also applies to many of the RF generators. C

This is what a real 8k ultra control box looks like, not a converted 3k ultra Going through it then will sell. Assuming not too messed up. 2024-07-04 08:23, Jim VE7RF wrote:

Clean Alpha 87A Full Legal Limit + Located in Southern California, Inland Empire. Avail. for local demonstration. Pair of Genuine USA Eimac 3cx800a7's Unlocked for 12 meter and 10 meter operation. Full HF coverage includes WARC & MARS operation. Factory installed optional external fan, allows 100% Full Duty Cycle, unlimited full power key down all modes. Including amp killer FT 8 Upgraded AlphaMax firmware for dynamic automatic tune, dynamic peaking for maximum power efficiency, automatic band selection and remote computer operation direct, or across network and internet for remote station operation. Local pickup is preferred... Shipping available with additional handling and packaging at buyers expense. Transformer will be removed and the amplifier will ship in two separate, certified shipping cartons, insured. I would expect approx $300 insured UPS Ground Additional shipping charges may apply Verify before purchase! Thanks for looking. Check out my latest QRZ.COM Logbook for latest DX worked using this amp... The amp is a joy and luxury to operate! I need to liquidate and may consider ready cash best offers,,, sooner before later! These second hand Alpha amps far exceed today's market value prices and probably represent the greatest Full US Legal limit amplifier value bar none! You can't get more bang for your buck value on any better amplifier, new or old! These are competion, top tier, world class luxury amplifiers that rate with production amplifiers twice their costs today.

I am located in Reno, Nevada. I say this right off the bat as this amplifier I am offering for sale, is too big for me to ship, so…… I have a 6 year old AL-82 legal limit amplifier to sell. I am pretty sure it has a shorted 3-500z tube. I know it has a suspect T/R relay. Rather than spend the money for 2 new tubes, I opted on purchasing a new solid state legal limit amplifier (RF2K-S) from Island Amplifiers. So…. The AL-82 is for sale. I will include 3, new, T/R boards for the amplifier. (AL-82’s have known issues with the T/R relays, so to make sure I would not have any parts availability issues, I just bought 3.) It is also wired for 240v operation. I also have the factory manual…somewhere..if I can’t find it, I will print out a good copy. It is a great amp, capable of well over legal limit, if that is your bent. I found 500 watts was all I ever needed for my communications and it just loafed along at that power. In any case, I am asking $1200 for the amp and spare T/R relays. Again, no shipping. I am handicapped and I can no longer take it apart to ship. Inquiry’s can be sent to my email address above. Joe – W7RKN Reno, Nevada