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1. [Amps] al-1500 parasitic?? or some other problem? (score: 1): Author: k1ttt@arrl.net (David Robbins); Date: Mon, 13 May 2002 20:45:00 -0000; This problem has developed sometime in the last 6 months or so, but has taken some time to pin down as it seemed intermittent and was being blamed on other things. It did not exist when I first insta; /archives//html/Amps/2002-05/msg00182.html (9,925 bytes)
2. [Amps] al-1500 parasitic?? or some other problem? (score: 1): Author: k1ttt@arrl.net (David Robbins); Date: Tue, 14 May 2002 20:55:39 -0000; Ok, thanks for all the testing suggestions and comments. Below I will try to answer all the questions and suggestions so far. I also find it hard to believe it is produced by the amp, but am running; /archives//html/Amps/2002-05/msg00198.html (10,751 bytes)
3. [Amps] al-1500 parasitic?? or some other problem? (score: 1): Author: k1ttt@arrl.net (David Robbins); Date: Tue, 14 May 2002 22:30:11 -0000; At this point nothing is a stupid question, I am definitely confused. I am using other radios in the shack to measure it. It was first noticed for the bad clicks on 15m. The 15m station has an ft-100; /archives//html/Amps/2002-05/msg00201.html (13,896 bytes)
4. [Amps] al-1500 parasitic?? or some other problem? (score: 1): Author: k1ttt@arrl.net (David Robbins); Date: Thu, 16 May 2002 14:31:53 -0000; Actually 'subharmonic' is a technically valid term. While not often used in hf radio it is frequently used in mathematical contexts when talking about sets of periodic functions, in microwave circuit; /archives//html/Amps/2002-05/msg00243.html (10,260 bytes)
5. [Amps] al-1500 parasitic?? or some other problem? (score: 1): Author: k1ttt@arrl.net (David Robbins); Date: Fri, 17 May 2002 13:03:37 -0000; Well, I can now say for sure that it is not the amp. I have found that by feeding only the top 6 ele 20m beam and pointing it either due east or west I can generate the f/2 and 3f/2 products with as; /archives//html/Amps/2002-05/msg00269.html (10,011 bytes)
6. [Amps] al-1500 parasitic?? or some other problem? (score: 1): Author: k1ttt@arrl.net (David Robbins); Date: Sat, 18 May 2002 10:55:41 -0000; Yes, the f/2 and 3f/2 both track the 20m transmitter exactly, so its not mixing with some other signal, its all due to that 20m signal somehow. It is also related to wx somehow. Yesterday when I got; /archives//html/Amps/2002-05/msg00289.html (12,998 bytes)
7. [Amps] Non-linear subharmonics was: Nonsense, AL-1500 parasitic (score: 1): Author: k1ttt@arrl.net (David Robbins); Date: Wed, 22 May 2002 20:03:54 -0000; Check out http://www.k1ttt.net/subharmonics/subharmonic.htm for the circuit I used and picture of scope traces. It is bigger than I wanted so it may take a while to download. As for the use of 'subha; /archives//html/Amps/2002-05/msg00359.html (9,844 bytes)
8. [Amps] RE: [Amps] Subharmonic (score: 1): Author: k1ttt@arrl.net (David Robbins); Date: Thu, 23 May 2002 15:02:51 -0000; No, I don't have a spectrum analyzer. I just put a short clip lead on another radio and hear it on that. As expected it does have many sidebands and when keyed with cw the clicks are very wide, obvio; /archives//html/Amps/2002-05/msg00382.html (9,690 bytes)
9. [Amps] Sale of CB amps on eBay (score: 1): Author: k1ttt@arrl.net (David Robbins); Date: Sun, 26 May 2002 17:12:13 -0000; Here, add these to your hit list. I have sent Riley these and haven't heard anything either.... davemade amps rival California kw's, anybody want a 30kw mobile amp?? http://www.bigradios.com/bulldog/; /archives//html/Amps/2002-05/msg00439.html (9,947 bytes)
10. [Amps] rx noise? (score: 1): Author: "K1TTT" <K1TTT@ARRL.NET>; Date: Sat, 06 Dec 2008 15:11:58 +0000; I have a commander hf-2500 (pair of 3cx800a7's, no qsk) that seems to be working fine. However, during cqww cw last week I had to pull it off the 20m station because it was making a broadband noise w; /archives//html/Amps/2008-12/msg00119.html (7,187 bytes)
11. Re: [Amps] rx noise? (score: 1): Author: "David Robbins K1TTT" <k1ttt@arrl.net>; Date: Sat, 06 Dec 2008 23:46:56 +0000; I really, REALLY hate intermittent problems like this... it wouldn't do it cold. So I started warming it up, after 1/2 hour or so I got the transformer up to 225f, the rf deck surface about 150f, the; /archives//html/Amps/2008-12/msg00128.html (13,036 bytes)
12. Re: [Amps] Fw: rx noise? (score: 1): Author: "David Robbins K1TTT" <k1ttt@arrl.net>; Date: Sun, 07 Dec 2008 11:55:04 +0000; The plate voltage fluctuation is from line sag from another amp running the 160m contest. It may have been modulating the noise a bit, but didn't appear to be the cause or a direct effect of the nois; /archives//html/Amps/2008-12/msg00136.html (11,642 bytes)
13. Re: [Amps] rx noise? (score: 1): Author: "David Robbins K1TTT" <k1ttt@arrl.net>; Date: Sun, 07 Dec 2008 12:00:31 +0000; Some cold snowy morning, like this morning, I may sit down and hold a rtty contest with it to try some more. I'll likely check some of the switching circuit today and make sure the bypass caps are i; /archives//html/Amps/2008-12/msg00137.html (9,381 bytes)
14. Re: [Amps] rx noise? (score: 1): Author: "David Robbins K1TTT" <k1ttt@arrl.net>; Date: Sun, 07 Dec 2008 12:06:53 +0000; The plate voltage fluctuations are from line sag from another amp running the 160m contest. I couldn't sort that out last week with the m/m operation, but yesterday's test showed that the noise occur; /archives//html/Amps/2008-12/msg00138.html (16,777 bytes)
15. Re: [Amps] Fwd: rx noise? (score: 1): Author: "David Robbins K1TTT" <k1ttt@arrl.net>; Date: Sun, 07 Dec 2008 12:21:15 +0000; There were several vintages of the commander hf-2500 and along the line he raised the plate voltage. The older ones I have only start at about 2kv on the plate, the new ones are about 2.7kv. And yes; /archives//html/Amps/2008-12/msg00140.html (19,255 bytes)
16. Re: [Amps] Fwd: rx noise? (score: 1): Author: "David Robbins K1TTT" <k1ttt@arrl.net>; Date: Sun, 07 Dec 2008 12:27:46 +0000; p.s. with practice you can clean those relays in about 10 minutes. Leave the top and bottom covers on, take off the back plate and tilt it back and you can reach in with medical forceps to clean the; /archives//html/Amps/2008-12/msg00141.html (19,453 bytes)
17. Re: [Amps] Plate choke resonanse and safe operation (score: 1): Author: "David Robbins K1TTT" <k1ttt@arrl.net>; Date: Sun, 07 Dec 2008 18:40:09 +0000; A handy tool for checking amp component temperature is an infra-red thermometer. These are available from a variety of sources. I got one from sears that goes up to 1400f and also includes a thermoco; /archives//html/Amps/2008-12/msg00146.html (11,854 bytes)
18. Re: [Amps] Fwd: rx noise? (score: 1): Author: "David Robbins K1TTT" <k1ttt@arrl.net>; Date: Mon, 08 Dec 2008 23:28:36 +0000; I think the noise in that one is solved... take a look at the scope pic for a 12v regulator with a 2v p-p oscillation on it at: http://wiki.k1ttt.net/2008%20Maintenance%20and%20Upgrade%20Blog.ashx?No; /archives//html/Amps/2008-12/msg00160.html (8,978 bytes)
19. Re: [Amps] Fwd: rx noise? (score: 1): Author: "David Robbins K1TTT" <k1ttt@arrl.net>; Date: Tue, 09 Dec 2008 22:45:22 +0000; According to the schematic there is a .1uf on the input, I didn't try to follow the tracks to see where it was though. There is no output side cap at all. David Robbins K1TTT e-mail: mailto:k1ttt@arr; /archives//html/Amps/2008-12/msg00181.html (10,608 bytes)
20. Re: [Amps] Fwd: rx noise? (score: 1): Author: "David Robbins K1TTT" <k1ttt@arrl.net>; Date: Tue, 09 Dec 2008 22:50:46 +0000; p.s. as I noted in my blog I have heard similar wandering birdies before but never had them land on a band like that one did during cqww. I have been doing other repairs on those amps so they have mo; /archives//html/Amps/2008-12/msg00182.html (10,884 bytes)

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