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Posted: Sunday 8th May 2005, 8:54
I'm looking for suggestions on some nice used test equipment to get for tuning radios. I used to work as a technician, but could no longer work for the owner of the shop, as he was useless as far as getting paychecks correct and on time. I've used the ifr 1200S and ifr 500a service monitors, and also a motorola service monitor, don't remember the model, but I just don't have that kind of cash to fork out. (it's a shame, too, because I'd love to get my greedy little paws on another ifr 1200S....LOVED that monitor). So, again, any suggestions as to relatively inexpensive quality testing equipment would be appreciated.
Posted: Monday 9th May 2005, 19:24
A decent wattmeter, like a Bird with a PEP adapter, a 'scope with response to 50 MHz, a counter with an external 'probe' input and a decent signal generator should get you by.
A stable, precise 1 kHz tone generator with a speaker on it is the easiest way to set SSB transmitters on frequency. Had to build ours, not sure where to send you for that item.
The signal generator is the sticky item. It needs to be stable, and have a calibrated output. Most "budget" RF signal generators are not stable enough to use with a SSB receiver, and the calibrated output attenuator is an expensive item all by itself. An under-$200 type will almost never include that, but an UN calibrated output. Many of those will 'leak' several microVolts of output turned down to "zero".
Bought a Boonton 102C sig. gen. on Ebay a few months back, didn't think to ask why the display was dark in the picture. Found out when it arrived. Internal shield covers were missing, the fuse was blown, and the tops blown (literally) off the tops of chips in the power-supply regulator circuits. Now I know never to bid on anything that isn't fully "lit up" in the auction photo.
The venerable, old Heathkit "Cantenna" dummy load has a useful feature for AM/SSB radios. A signal tap-off that's attenuated and rectified with a signal diode. It's meant to be used with a DC voltmeter, to read relative output power. By changing the .01 uf disc cap across the DC output jack to a .001 or so, and shunting 10k across it, a patch cord to the 'scope input will display the modulation envelope. Nearly any cheap scope, no matter the rated vertical frequency response can be used to observe the output of a transmitter into the dummy, since all that comes out of that jack is the demodulated audio, riding on a DC voltage in proportion to the carrier level.
A high-precision, stable synthesized signal generator is a big plus, but not cheap.
The single most-used tool here is a so-called "component tester". I'm told that in the Navy technical command, it was nicknamed the "octopus". It's a two-terminal curve tracer that feeds (on our unit) 2 Volts peak-to-peak AC out the two wires to the probe. The vertial axis on the scope is current, the horizontal is voltage. With no circuit across the probes, you get a flat baseline, all voltage no current. With the probes shorted, you get a vertical line (all current, zero voltage). A semiconductor P-N junction will show a "dog leg" trace, flat on the reverse-bias side of zero, and a vertical "leg" about 6/10 of a volt to the right of center. Mighty handy for identifying blown or damaged junctions in transistors or diodes. Since it's much faster than a meter, you can see the "noise" on a scratchy or intermittent switch when it is opened and closed. A pot with a bad spot will be immediately evident when it's turned.
Several kinds of oscilloscope from MCM, Beckman Industrial, and Elenco have been sold with this "component tester" feature built-in. Most of those place 10 or 20 Volts P-P AC across the probe tips. It places a forward-biased junction "knee" much closer to the baseline's center point. They will permit you to see the "knee" of a low-voltage zener diode, where our 2-Volt version will not.
It's an overlooked kind of tool, but has been an enormous time-saver for us. A commercial version called the Huntron Tracker has been on the market for a while, but the prices are out of reach for me.
Best of luck on getting set up. One more little item that I have found very useful is a 'scope that has a sample of the vertical channel available on a "channel 1 output" socket. Higher-ticket Tek analog 'scopes come with that feature. We patch it into a frequency counter. Turns the 'scope's vertical channel into a broadband preamp for the frequency counter. Makes it possible to use a times-ten 'scope probe to read internal frequencies in the radio that would be too weak for the counter to read with the probe plugged directly into it. Touching a probe to a crystal oscillator circuit will "load" the circuit since there is always capacitance to ground inside the probe. When you remove the probe, the frequency will shift from what it was while you were reading it. Using a 'scope's input channel as a preamp allows touching the probe to the metal case of a crystal. So long as there is no ground wire on the crystal's case, you will pick up enough of the crystal's waveform with the vertical sensitivity turned up, and get a reading with nearly no disturbance to the setting of trimmer caps.
Well, that's a little more than two cents' worth, maybe a quarter.
Best of luck and 73
Posted: Monday 5th Sep 2005, 2:50
I think it all coms down to your budget.
I have a HP 8920 on a perminant loan from a previous
employer, this with a CRO and a lab power supply coveres most of my needs. The trouble is if I had to buy one I'd be out of pocket about $8500
second hand. I've used the IFR and the Motorola and they are also great units. Ive seen the IFR 1200s go for about $3500 and Marconi's for $2800 (not a fan) at auction in Queensland when Accord bought out a lot of the Modile phone service centres. You may find this were you are as well as they are little use in the repair of the GSM, CDMA and 3G handsets. (You may be able to aproach one of these places or keep and eye out for them in the auction catalogues and online [Greys])
The other alternative is to buy separate items;
eg Frequency Counter, CRO, RF Gen, AF gen, Spectum Analiser, RF meter etc
This is a cheaper option but the gear will likely to be older or end up costing more once you have everything you need.
By the sounds of it you have been spolt like me and its hard to multiple bits of gear. One last bit of advice.. beware of the older all in one units they are often faulty, way out of cal, no info available to repair them. I bought an old English unit $500 and found the stepped attenuator and the conical filter were both crook. (Now very expensive and heavy audio generator but still looks impessive in the shack)
Cheers for now
Posted: Thursday 31st Aug 2006, 18:13
nomad, that is a pretty great rundown. I had wondered about the type of equipment a tech uses, now I have an idea.
Any info on Energy Concepts O-Scope you could share??
Posted: Sunday 25th Feb 2007, 16:40
Anybody familiar with the Energy Concepts Inc. Model ECI-60 O-Scope? I just picked one up onlinefor a good enough price that I could just about either donate it or sell for parts if it has issues. So I'm not hurt on the deal anyway it turns out...
Anyway, it came from a surplus auction and the only info I have is that it is a "Dual-Trace Triggered Sweep Oscilloscope". It didn't have much info and I couldn't read the small print on the tag to see much but from the P/N, I think it may be a 60MhZ unit.... then again, maybe not.... it's been about 30 years since I have even looked at a scope to buy for personal use so I've been out of the loop for a bit.
I wondered if anyone had heard of or had any info on one of these that might shed some light for me. Capabilities, durability, company reputation, etc.
I was looking for one to work on my 10, 11, and 12 meter rigs, primarily but possibly others as my collection expands.
the Voice of the Ozarks
Posted: Thursday 27th Mar 2008, 19:40
I'm looking to get some test equipment also, I have no idea what to get, up until now I have just been doing tune ups and a few mods, and am wanting to get further into repairs, as all of our repair shops in this area are dissapearing, and I have been getting more and more radios to work on but don't have the right equipment, and have no idea what to get.
I need to know what to look for in a scope, signal generators, and anything else I would need to get going. Give me a few model numbers to check out so I know what to look for.
For examle, I have a few radios here now that have recieve problems, and 1 that has output audio issues.
Someone told me I should get or make a signal tracer, and get a tone generator for recieve.
Let me know what you think.
Posted: Tuesday 16th Dec 2008, 19:11
I was at the TRW swap meet a few weeks ago. I was able to buy a Bird 43 meter in perfect condition for $175. the slugs were another $40 each.
there was this guy selling Tektronix oscilloscopes for $20 each. he had a whole truck load of these things. all of it was all junk.
I bought a RF Generator for $10.00 from this guy. I ended up spending $30 to fix it. I changed out all the electrolytic capacitors, and the FET and other transistors. the thing will hold a + or - 200hz.
as to what you were saying about low end RF Generators, I don't want to try and squeeze any more out of it.
Posted: Wednesday 17th Dec 2008, 16:01
does any body know where to get service manuals and circuit diagrams for BK Precision equipment.
Posted: Sunday 4th Jan 2009, 4:22
Hope this helps http://www.freeinfostuff.com/
Brian's info page.
Posted: Thursday 29th Jan 2009, 6:18
I am looking for a manual for an old BK Precision 2005A RF generator. I paid $10.00 for the thing. I rebuilt it and it's much more stable.
I was able to get the owers manual for the 2005B. it is close, but it's not the same. a schematic would be nice.
the people at BK Precision are a little stingy with information about their equipment. they don't want to give out information on their older equipment. they just tell you to bring it in for an up grade trade in credit.
Posted: Sunday 1st Feb 2009, 7:57
Have you tried www.bkmanuals.com
? or www.surplussales.com
They have a large selection of service and owners manuals.
Re: test equipment
Posted: Saturday 30th May 2009, 8:31
A lot of companies have all of their stock online so you can be updated on products they have. I know that TekNet Electronics
not only sells all kinds of used test equipment, but also buys- which is a plus since I know a lot of people are strapped for cash right now. So if you have some laying around, contact them.
Re: test equipment
Posted: Saturday 11th Sep 2010, 6:58
Another good site to try for test equipment and repair is http://www.testequipmentrepair.com
They work with a lot of different categories and brands.