My Tektronix and HP Shop Instrumentation 

Your story is dear to my heart. I have been a ham since 1963 and I absolutely loved ham fests. Unfortunately, here in the middle of nowhere in the beautiful and wonderful desert southwest, they hardly exist at all and the ones that do occur are really sad. I came here from Huntsville, AL, where we had some really nice ones but I left there in 1976 for El Paso and White Sands Missile Range. I was a NASA contractor in Huntsville. I remember saving money and buying an Eico model 460 (?) scope when I was a 16-17 year old kid and was sorely disappointed with it but at the young age of 20 finished college and went to work as the NASA contractor and ... wow... those little portable 453 scopes were a dream come true. We actually still had some vacuum tube Tektronix scopes on carts we used in the high speed cabinets of 1200 baud communication lines... :-) The old scopes worked great for that purpose. Surprisingly, there is a lot of government and military here in the El Paso area, WSMR, Fort Bliss, just north in Albuquerque, Sandia Labs, Los Alamos, and I have worked at all of them but the amount of equipment around here is almost nothing and if you try and sell your high-end equipment in this town, you are likely to get nothing but recycled metal price for it. Sad but true. So..... I have to agree that there are some absurd prices on some items on Ebay but that is where I have gotten most of my equipment and either I am lucky beyond imagination or what, I don't know, but I have some beautiful performing equipment that I have picked up and is my only source for equipment and parts. There is one tiny electronic shop here in El Paso, and I love the guys there but they have nothing... I have a real appreciation for the GR equipment. I think most of it only got used by guys working on their graduate degrees and it was brought out of the locker for a few minutes for them to see and maybe touch then it was inventoried and scurried back into a secure closed. Guess that is good for me to have such beautiful equipment 70 years later. I use my vintage GR equipment to test the fancy-dandy digital equipment I buy today - As a much younger fellow before I had all of my own high-end test equipment all I had was stuff like Eico and Heathkit and during measurement, things just didn't turn out right. Part of it was my lack of knowledge and experience and part of it was the +_20% equipment I was using. I love my shop. It keeps me sane. Before I retired in 2010, I was a manager for 11 years on a INS/DHS contract and afterwards a technical writer for the army but it was not my cup-of-tea. I need to be in a lab or technical environment and not dealing with people. I know now why science and math are so simple - pretty much, what is true today is true tomorrow. I know science changes but managing people is not what I like to do. Thanks for you comments. I really enjoyed reading your experience.

Thanks for your comments. Tektronix is proud of their MCP technology, as they should be that will display these fast signals at low repletion rate that you mention and I love the scope but I wish I could have the trace stay on all the time and not have to be continually moving something on the front panel to keep the trace on. They seem to be overly concerned with "differential aging" as they call it. I have the operator's manual but I can't find a way to override the trace turning off every few minutes. Do you know to keep the trace on ?

ElPaso TubeAmps Don't give up. See Appendix C in the user doc for a configuration menu setting that lets you adjust the time out on the screen. I left it alone. Funny, it drives me crazy, too, but in truth to prevent burn-in I try to turn down all CRT instruments manually, so I rationalize this as a handy feature.

pithandmoment Thank you very much. I did find it with your help. EXER 09 it says: " xx > 90 gives continuous timer display". I will have to play with it but your thoughts on leaving this parameter alone is probably the wisest thing to do.

This seems so long ago although it was only four years. I no longer have the HP 353A patch bay but when I had it I used it as an attenuator for my oscillator, if I remember correctly. A really nice piece of equipment but I have replaced it with simpler HP 600 ohm audio attenuators -

Hi Frank - I am not aware of any audio signal generator plug in modules for the 7904 - I agree that would really be nice to have.

I do not have a place to send for calibration. Some calibration I can do myself but generally, if the need arises, I compare one instrument to another. The Tektronix meter is the newest so I make a measurement, voltage for example and then with two or three other meters at the same time and compare the readings. Often times they are within 0.01% of each other so I assume all is well. For resistance I have precision resistors to 0.01% so I use them for that type of check. That is pretty much the way I keep tabs on the accuracy of my test equipment.

Hi Rick, I have a similar problem depending on the sensitivity setting of my Tektronix frequency counter. It is a push button setting between high and low input levels and one way it has no effect and the other way it increases THD on the line significantly. I don't remember the exact amount of THD increase and don't know why. I get my lowest THD at the upper frequencies of the SG505/AA501 and wonder if that is true for you. I generally don't think much about it anymore if the input level is below 0.00xxx %. I might mention that in my attempt to keep the noise floor as low as possible, I have tried isolation transformers on all pieces, separate pieces of equipment, etc. It is tricky and sometimes it seems better and sometimes worse or no change. I do remember changing out the fluorescent lamps over my workbench to direct replacement LED lamps and that did make a difference in my noise floor. I know I am talking about noise floor at the moment but I have found it tricky to get below a -90 dB S/N level. Even the BNC cables make a difference and the grey HP (10503A) cables are better by several dB. Not sure what to suggest but I don't think it is the additional 1 meg load on the line. Possibly plugging all the instruments into the same power strip (?) if you haven't already. Just guessing. Hope this helps.

@@ElPasoTubeAmps Morning David, I have a couple long strips that plug into the same outlet (star style). I am able to pull the 0.0007% from 1k-10k. Degrades a little over 10k. My cables are homemade RG316. If I move the BNC connectors into the wrong position it will raise the distortion. I'll reconfigure it with just my Pomona cables to see if it corrects it. I'll check the noise floor with a HP 3562A and 3580A. Love all these old instruments.

Hi Glenn, The sweep oscillator is a Tek FG-504 - it is a double wide module but is actually a TM500 series. The only TM5000 series module I have is the DM5010. From your posting here, I have been playing with the FG504 over the weekend and maybe I should make a quick video on it. I would think you should be able to sweep 400 - 500 KHz for nice alignment of your IF filters. It is rated up to 40 MHz. I have done some nice 20 meter antenna experimenting with it, some time back, by sweeping, 14.0 to 15 MHz and watching the amplitude of the sweep on the SA - first noting the amplitude of the sweep with a 50 ohm load then 100 ohms and 25 ohms for amplitude reference points. I get some really interesting results that may have real value. Another video, huh ? And your Altec 350A - I looked it up and they are beauties - very nice score. Several years ago I went to a sale where I picked up a Altec amp (can't remember the model) that ran a pair of 811A's as finals. It was laying in the sand and I asked what he wanted for it and he just told me to "take it". Naturally, I cleaned it up and played with it for a few months and then sold it on Ebay for $480, plus... another $480 for UPS to deliver it to Australia - yes indeed $960 was spent on the beauty I picked up out of the El Paso desert sand for free. It was huge with those beautiful Peerless transformers and chokes - I think that model was commonly used in the old drive-in movie theaters to run all the speakers. If I had it today I would probably get $2K for it :-)) 73 WA4QGA

wa4aos Hi Glenn - haven't heard you on lately and just wanted to check in with you and make sure you and yours are doing good. All is good here - nice weather, etc. Drop me an email when you have time. theaudioshop@sbcglobal.net

+Kevin mc burnie I also have other Tektronix mainframe modules (i.e. TM 506 and TM 504) but I have never had any issues with the plug-in compartments so I am not aware of any fuses. It would not surprise me if each compartment was individually fused. I would give it a good visual inspection and make sure all the fuses are of the correct value and in good shape. I know in my TM 506 unit the right hand compartment is labeled "high power" as it appears it will run modules that require more current. I hope you get it working.

thanks .I love your channel thanks for replying.

QuadMaestro My 7L5 had some switch issues and was very temperamental so I ended up selling it on Ebay. When mine wasn't being kinky, it would have been able to do 19KHz and 38KHz perfectly but audio frequencies were just too hard to deal with. (it is hard to remember what all the buttons are for...) The HP 3580 is a 5 Hz to 50 KHz SA and it does a really good job at audio as you would expect. Unfortunately, you can't see anything but the second harmonic on a 20 KHz signal which is why I bought the 7L5. I guess realistically, we don't need to see anything past the second harmonic of 20 KHz in an audio signal. I also have the 7L12 and it is a beauty. If you see my video that I published recently on using the 7L12 in the 7904 main frame, it can operate like a modern day MDO - please check this video out and let me know what you think - ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-y7uMl-erdCk.html I purchased the FG504 to do audio sweeps but low frequency (20 Hz) distortion is unacceptable which drove me to the HP 8903. I think it is a great FG but not for the audio range. For higher frequencies I purchased the HP 8596E SA and HP 8648C signal generator. I have always had a keen interest in the 2.4 GHz region

ElPaso TubeAmps Thanks for your reply. Saw your MDO video too. I am looking at FG504 because I occasionally need something to do AM alignments, with IF around 455-470kHz, and also more commonly FM IF alignments at both 10.7MHz and 12.5MHz (Leak Troughline). I haven't found any single instrument that will do all that. Sencore 165 does all but the 12.5MHz but they are getting hard to find. It looks like an FG504 might fill that bill, whaddya think? & can it do markers? or any other recommendation? NB another thing I do like about the 7L5 was no extra display, as I have zero excess space. You can choke it down to 20kHz or 50kHz.

QuadMaestro I have the FG504 and a Wavetek 2001 that work properly and I am willing to sell at the fair-going price that I paid for them. The FG504 is a complicated device to learn to use - even more so than the 7L5 :-) in my opinion... I don't know the dollar amount but we can get a "fair" price from Ebay and I will research what I paid for them. If you buy them and don't like them, you can send them back, you pay return postage. I used to sell on Ebay but too many scams where people claim what they got was "not as advertised" and get the seller to refund some of the money via PayPal. I buy off Ebay all the time because as a buyer, everything is on my side and Ebay is the Only place to buy the stuff I want. I am ElPasoTubeAmps on Ebay also. You can contact me directly at rdavidbeard@gmail.com if you are interested. I don't remember, if I ever knew, all the features of these two instruments but they can be researched easily. I assume you are in the USA (for shipping)?

ElPaso TubeAmps Thanks again, taking the dscussion offline.

I should correct a statement I made above. I misread the 7L5 specifications. SNR is -80dB.

Anders - I did get it operating and have used it many times. I made a number of YT videos about it but I have not gotten into programming it for other purposes so anything you have I am definitely interested in. I have discovered, as others have, that he voltage level cannot be controlled to stay set at a level on scans using the Pete Millett programs (I think that is the issue). It has been a while since I have used it as I have moved to my other hobby of RF. I can be reached directly at rdavidbeard on my gmail account. Thanks...

Hi John, the DM5010 does not have the feature to read watts. Actually, my DM5010 is somewhat out of calibration and I never use it. I have attempted adjustment on it a couple of times but I can't seem to figure it out. Not sure what the problem is. I bought if from an Ebay seller in Albuquerque and talked to them soon after purchase when I noticed it was not correct but was assured it was in calibration but it is not.

Besides the 8903, do you have any other meters that will do this function? I seem to recall another one of your meters would do this. I do enjoy your videos and try to watch one every few days, thank you for giving people like me clarity, you missed your calling and should of been a teacher!

Thank you. I do try to give away what I have loved to do all of my career in these videos. I am glad you enjoy them. The 8903 and HPIB/GPIB - USB device and Pete Millett's programs is a high-end good way to go and you get laboratory grade results but an inexpensive USB sound card ( around $60 or so) and a PC will allow you to run ARTA or SpectraPlus software that will do a good job also. Same is true for the HP3580A audio spectrum analyzer as it is a lab grade instrument but there are so many solutions nowadays that these 40+ year old instruments are probably not the best way to go anymore. I have the 3580A and I trust it but is soooo slowwww when looking at signals below 100 Hz that it is painful. If you can get a USB sound card try searching for and downloading ARTA or SpectruPlus and I think you will be pleased.

I think you are a normal healthy geek. I spend as much time as I can with my instruments and hobbies.

Honestly, I'm happy for you ! For me, you represent an ideal way of life. I wish you well for years to come.