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OldGuy <spamfree@nospam.com>: Nov 29 03:35PM -0800 Looking for recommendations for a Grid Dip Meter built or a kit.   --- news://freenews.netfront.net/ - complaints: news@netfront.net ---

Jeff Liebermann <jeffl@cruzio.com>: Nov 29 04:16PM -0800 On Sun, 29 Nov 2015 15:35:20 -0800, OldGuy <spamfree@nospam.com> wrote:   >Looking for recommendations for a Grid Dip Meter built or a kit.   It's now called a GDO (grid dip oscillator). Here's a page of various manufacturers and models: <http://www.n4xy.com/gdos.html>   I have three Heathkit HD-1250 GDO's. Not the best. You can get what might be a clone of a Heathkit HD-1250 from MFJ: <http://www.mfjenterprises.com/Product.php?productid=MFJ-201> Also, check out the sold listings on eBay for approximate pricing: <http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=grid%20dip%20meter&LH_Complete=1&LH_Sold=1&rt=nc&_trksid=p2045573.m1684>   Sorry, no recommendations as all my stuff is ancient.   -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

Cursitor Doom <curd@notformail.com>: Nov 30 12:33AM On Sun, 29 Nov 2015 16:16:27 -0800, Jeff Liebermann wrote:   > Sorry, no recommendations as all my stuff is ancient.   So's a lot of my stuff. But there's nothing wrong with old gear IMO it's the quality of it and whether it's in calibration that counts. The only issues with GDOs IME are that they're not too bad for the lower frequency RF stuff, but hopeless for anything higher.

Sjouke Burry <burrynulnulfour@ppllaanneett.nnll>: Nov 30 01:56AM +0100 On 30.11.15 0:35, OldGuy wrote: > Looking for recommendations for a Grid Dip Meter built or a kit.   > --- news://freenews.netfront.net/ - complaints: news@netfront.net ---   In google (images) about 10 solutions.

Jeff Liebermann <jeffl@cruzio.com>: Nov 29 05:40PM -0800 On Sun, 29 Nov 2015 16:16:27 -0800, Jeff Liebermann <jeffl@cruzio.com> wrote:   This looks very interesting: <http://www.qrpproject.de/UK/dipit.htm> No clue how to purchase one and it's only 1 to 42 MHz.   May 2003 QST article on building a "modern" GDO: <http://www.qsl.net/k8mcr/downloads/Modern_GDO.pdf>   Feb 2013 Circuit Cellar article on building a GDO: <http://circuitcellar.com/wp-content/uploads/2013/01/CC25_ProjCard_Pres_Ball-CC271.pdf>   Goes to 1GHz by changing both the oscillator and the coil with frequency range. See "Plug in Oscillators" section: <http://elm-chan.org/works/ddm/report_e.html>   July 2014 QST. Using an MFJ-259/269 as a GDO: <http://www.ka6wke.net/finished-projects/grid-dip-meter-coils> MFJ sells these as MFJ-66C: <http://www.mfjenterprises.com/Product.php?productid=MFJ-66C>   More: <http://w5dor.com/W5DOR-GridDip.html>   -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

Michael Black <et472@ncf.ca>: Nov 29 09:03PM -0500

Michael Black <et472@ncf.ca>: Nov 29 09:17PM -0500

mike <ham789@netzero.net>: Nov 29 07:53PM -0800 On 11/29/2015 6:03 PM, Michael Black wrote: > frequencies, a lot of the coils were shielded. There were GDOs that > worked well at VHF and UHF.   > Michael   Best one I ever used was the tube version of the Millen. I switched to the solid state version and regretted it. Much less sensitive and more fiddly than the tube version. Tunnel dipper was the worst for sensitivity.   If ham swapmeets are any indicator, most GDO's available second hand are missing some or all of the coils.

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Nov 30 10:08AM -0500 On 11/29/2015 06:35 PM, OldGuy wrote: > Looking for recommendations for a Grid Dip Meter built or a kit.   > --- news://freenews.netfront.net/ - complaints: news@netfront.net ---   Find an old Measurements (Boonton) 59 'Megacycle Meter' on eBay. I used to have a Heath 12something that I used for years. On Joerg's recommendation, I got a Measurements 59, and soon afterwards the Heath went in the trash.   The 59 has accurate frequency calibration. Mine is still within 2% over the full range, by actual measurement, and it hasn't been trimmed in a loooong time. It also gives a nice deep dip even with quite weak coupling--much weaker than the Heath, especially on low-Q resonances. I've used it to measure the coupling coefficient of toroidal transformers, for instance. (An ISDN unit had a CC of 0.99986.)   Besides, it has such a nice retro look and feel.   Cheers   Phil Hobbs   -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics   160 North State Road #203 Briarcliff Manor NY 10510   hobbs at electrooptical dot net http://electrooptical.net

Leonardo Capossio <capossio.leonardo@gmail.com>: Nov 29 10:47AM -0800 El viernes, 16 de octubre de 2015, 1:54:16 (UTC-3), Phil Allison escribió:   > Those holes need to be de-burred in a drill press.   > Once done and regreased, output devices run cooler and there are no more shut downs.   > ... Phil   Right.   I'm starting to think this is the problem. I checked the trasistors and they are fine, they are the same as in the schematic.   Y removed them from the heatsink, cleaned everything with alcohol (even tried not to touch it with my fingers) and put fresh thermal paste (with isolation) between the metal plate that holds the transitors, between the plate and the heatsink, and between the heatsink and the case, but still the metal plate is hot as hell (can't even touch it) and the heatsink is very hot, but not so much.   I wonder if there is a video on how to do it properly.

"Ralph Mowery" <rmowery28146@earthlink.net>: Nov 29 02:18PM -0500 "Leonardo Capossio" <capossio.leonardo@gmail.com> wrote in message news:14fca79b-407a-43dc-93c7-99e24240bcdf@googlegroups.com... >plate and the heatsink, and between the heatsink and the case, but still >the metal plate is hot ?>as hell (can't even touch it) and the heatsink is >very hot, but not so much.     When putting the paste on, did you use the thinist layer you could ? The paste is not that conductive to heat, just beter than air. The ideal ammount (which probably can not be done) would be to have the metel surfaces touching each other on the high points and just the voids filled with the paste. Less is often beter than more.

dplatt@coop.radagast.org (Dave Platt): Nov 29 12:10PM -0800 In article <14fca79b-407a-43dc-93c7-99e24240bcdf@googlegroups.com>, >fingers) and put fresh thermal paste (with isolation) between the metal plate that holds the transitors, >between the plate and the heatsink, and between the heatsink and the case, but still the metal plate is hot >as hell (can't even touch it) and the heatsink is very hot, but not so much.   You might want to check the metal plate and heatsink for flatness.   If the plate was warped at all, it won't be making good contact with the heatsink - there would be a few small points or lines of good contact, and a significant air-gap everywhere else. Filling the gap with thermal paste won't help very much. Thermal paste helps thermal conductivity only when it's a very thin layer - just thick enough to bridge the occasional thin gap between two surfaces which are otherwise in good direct physical contact. A thick layer may be worse than not having it at all.   CPU overclockers used to (maybe still) "lap" the top of the CPU and the contact surface of the heatsink, in order to get the both as flat as possible. When this is done, the layer of thermal paste between the two is *very* thin... put a tiny dab on one surface, and then spread it out thin-and-even with a single-edged razor blade.   Over-torquing the screws which hold down TO-220 or similar plastic-package transistors to the heatsink can similarly cause problems. Apply too much torque, make the transistor case and tab flex a bit, and you end up pulling most of the case away from the heatsink and thermal transfer gets worse. If your transistor tabs are bent or warped, lapping them might help.   [Lapping of this type can be done with a sheet of wet-and-dry carbide paper, mounted on a flat plate of some sort - a high-quality sheet of plate glass will serve. The usual finishing technique of "start with a coarser grit, then work your way up through the grits until you get to 1000" would be appropriate.]   The fact that the heatsink itself is very hot does suggest that something else may be going amiss... maybe the transistor quiescent bias is too high, or maybe there's a parasitic oscillation taking place. Using a scope (or an old-style grid-dip meter in absorbtion mode) to look for RF where it doesn't belong might be a good idea.

M Philbrook <jamie_ka1lpa@charter.net>: Nov 29 09:02PM -0500 In article <14fca79b-407a-43dc-93c7-99e24240bcdf@googlegroups.com>, capossio.leonardo@gmail.com says...   > I'm starting to think this is the problem. I checked the trasistors and they are fine, they are the same as in the schematic.   > Y removed them from the heatsink, cleaned everything with alcohol (even tried not to touch it with my fingers) and put fresh thermal paste (with isolation) between the metal plate that holds the transitors, between the plate and the heatsink, and between the heatsink and the case, but still the metal plate is hot as hell (can't even touch it) and the heatsink is very hot, but not so much.   > I wonder if there is a video on how to do it properly.   If it's getting hot like that with the amp on and not generating any sound, you have other problems. Put a volt meter on the output in DC mode first, see if you are getting any DC above a few mVs   After that, put the meter in AC mode and see if you are getting AC ripple of a significant level, which you should not be.   Do this in ideal mode, no sound.   Me thinks you have big ISSUES with biasing.     Jamie.

Phil Allison <pallison49@gmail.com>: Nov 29 07:16PM -0800 Leonardo Capossio wrote:     > I'm starting to think this is the problem. I checked the trasistors and they are fine, they are the same as in the schematic.   > Y removed them from the heatsink, cleaned everything with alcohol (even tried not to touch it with my fingers) and put fresh thermal paste (with isolation) between the metal plate that holds the transitors, between the plate and the heatsink, and between the heatsink and the case, but still the metal plate is hot as hell (can't even touch it) and the heatsink is very hot, but not so much.   > I wonder if there is a video on how to do it properly.   ** Two things are not clear:   1. Does the heatsink get very hot whenever the amp is on or do you have to PLAY something ?   2. Have you found and fixed any burs on the holes in the heatsink coupler and or the chassis ?   BTW:   That amp has an odd, non adjustable bias arrangement.   Transistors Q14 and Q 15 should be in thermal contact with the heatsink.     ... Phil

Leonardo Capossio <capossio.leonardo@gmail.com>: Nov 30 06:23AM -0800 El domingo, 29 de noviembre de 2015, 16:15:36 (UTC-3), Ralph Mowery wrote: > touching each other on the high points and just the voids filled with the > paste. > Less is often beter than more.   Yes, I used a very thin layer.

Leonardo Capossio <capossio.leonardo@gmail.com>: Nov 30 06:29AM -0800 On Monday, November 30, 2015 at 12:16:15 AM UTC-3, Phil Allison wrote:   > ** Two things are not clear:   > 1. Does the heatsink get very hot whenever the amp is on or do you have to PLAY something ?   You have to play for a while at low volumes (10min tops), or play for a minute at the highest volume. In idle, with a plug connected (otherwise the amp mutes), it does not shut down.   > 2. Have you found and fixed any burs on the holes in the heatsink coupler and or the chassis ?   If by burr you mean what is described in this page: "http://www.nmri.go.jp/eng/khirata/metalwork/basic/bari/index_e.html", then I don't see any worrysome burr on the heatsink.   > BTW:   > That amp has an odd, non adjustable bias arrangement.   > Transistors Q14 and Q 15 should be in thermal contact with the heatsink.   They are on the heatsink, but their tab is completely plastic.

N_Cook <diverse@tcp.co.uk>: Nov 30 01:49PM Crackle just like cathode/heater leakage in one of the valves, but active test as perfectly good isolation . This crackle was present on first receipt testing but now with close-handling not the slightest trace - typical symptom of PbFitis , also can be similar "bacon and eggs" crackle . Any known problem area? hopefully not with the DSP chippery. ( just dealing with a Hartke HA3500 with pbfitis , but as 2006 a bit more excusable)

"Dusty" <dusty@mail.not>: Nov 30 03:54AM -0600 > > https://www.radioshack.com/collections/maker-s-t-e-m   > > It doesn't require bashing off the case of a store bought clock and putting it into a case, and calling it home made.   > Heheh... If little Mo made the theremin kit, Obama would have thought the aliens were landing....   It's easy to impress someone who doesn't know anything.   -- .

philo <philo@privacy.net>: Nov 29 06:54PM -0600 On 11/29/2015 9:36 AM, M Philbrook wrote:   > Jamie   yeah...I am presently scanning my old negatives and just came across a photo of me in my shack back in 1971

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