Analog meter
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W3FPR and others frequently recommend good quality analog meters for
doing several alignment procedures and for performing countless tests. I'd like to get one but have no clue what to look for in this day and age of digital test equipment. Advice, recommendations please? Thanks -- JT Croteau, N1ESE - Manchester, NH (FN42gx) _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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JT -
One of the best analog voltmeters is the Hewlett Packard 427A. It is functionally similar to the "standard" VTVM of vacuum tube days, with better accuracy and the bonus of some low-volts ranges. An excellent buy, and there are a couple on eBay right now for very reasonable prices. Here is one of them: eBay item number 250159852289. There are others listed as well. I have 2 of these and use them frequently, and as others have said, an analog instrument is hard to beat for tuning up the various stages in a transceiver. Standard disclaimers apply - no connection to seller, etc. - Jim, KL7CC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by JT Croteau
JT,
Most of the times that an analog meter is helpful is when making peaking adjustments to tuned circuits, so what you really need is a meter system that can detect and display the amplitude of an RF waveform - the following are suggestions: For a *really* fast responding 'analog meter', use an oscilloscope - the vertical deflection represents the voltage - the advantage of the oscilloscope is that it can work at low RF voltage levels as well as higher levels. Many DMMs have an "analog" bar graph display that is fast responding. Use in conjunction with an RF Probe. An older VTVM will suffice instead of the DMM, but also will likely be used with an RF Probe in most cases. Note that a VOM will not work very well because it loads the RF probe output significantly. An analog meter SWR meter will measure the relative level of RF at the transmitter ouptut - the peak is easy to see when making adjustments. This one is already available in many hamshacks and will suffice nicely as long as the transmitter is working. A very nice meter for measuring RF directly over a wide frequency range and from very low levels to quite high levels can be homebrewed - see the article from QST June 2001 page 38 titled 'Simple RF-Power Measurement' by Wes Hayward W7ZOI and Bob Larkin W7PUA. Fitted with an analog meter, this instrument will measure from nanowatts to a milliwatt, and when used with a 30 dB coupler like the Elecraft CP1, the range can be extended up to about 10 watts, or with the 40 dB Tap that is shown in the article, the range goes up to 100 watts. A very nice instrument indeed, but be careful to shield the input well, this is a VERY sensitive meter. 73, Don W3FPR JT Croteau wrote: > W3FPR and others frequently recommend good quality analog meters for > doing several alignment procedures and for performing countless tests. > I'd like to get one but have no clue what to look for in this day and > age of digital test equipment. > > Advice, recommendations please? > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by JT Croteau
I think the analog meter par excellence is the Avometer. Avo was a
British company that made avometers and tube testers. I think that the company has been taken over by Megger. Anyway, the Avometer has a sensitivity of 20,000 ohms per volt, a physically large scale with a mirror backing to avoid parallax errors. Expensive new, but I got mine from that watery place for about $100 plus the petrol for a 60 mile round trip to pick it up. Incidentally, I would not be without my DMM and my AADE LC II meter (for measuring capacitance and inductance.) 73 Kevin VK3DAP / ZL2DAP _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Kevin,
I beg to differ with you. While the 20,000 ohms per volt meters were great with vacuum tube circuits (except when attempting grid measurements), they will cause significant loading of many solid state circuits creating measurement errors. A DMM or VTVM has an input impedance in the range of 10 to 11 megohms and will not usually cause significant loading. There were several good quality VOMs available in the 60s having a 20,000 ohm per volt specification. Simpson, Tripplett and Avometer are among some of the names. Great VOMs, but their usefulness with solid state circuits has diminished because of their relatively low impedance. 73, Don W3FPR KBG Luxford wrote: > I think the analog meter par excellence is the Avometer. Avo was a > British company that made avometers and tube testers. I think that > the company has been taken over by Megger. Anyway, the Avometer has a > sensitivity of 20,000 ohms per volt, a physically large scale with a > mirror backing to avoid parallax errors. Expensive new, but I got > mine from that watery place for about $100 plus the petrol for a 60 > mile round trip to pick it up. > > Incidentally, I would not be without my DMM and my AADE LC II meter > (for measuring capacitance and inductance.) > > 73 > Kevin > VK3DAP / ZL2DAP > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by KBG Luxford
On Sunday 30 September 2007 21:36:16 KBG Luxford wrote:
> I think the analog meter par excellence is the Avometer. The Avometer has only one linear scale, as I remember. All those cramped at one end AC scales on other meters are clumsy by comparison. The 20,000 ohms/volt lack of sensitivity can be overcome by modern high gain, high impedance linear amplifiers for a particular range. I never owned one, but I used them often at school when I was around 15 years old. Elegance par excellance. Ian, G4ICV, AB2GR, K2 #4962 -- _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by JT Croteau
I bet you could pick up an RCA Volt-Ohmyst (SP?) for next to nothing.
Probably one of the most popular bench top meters of all time.. . . next to the Heathkit jobs. I just saw a post a few days ago for a digital with an analog combined. I wouldn't bother if the analog part is a bargraph. get a VTVM or FETVM with the D'arsonval meter. Old HP's are very good (accurate) but not as portable. Al WA6VNN ************************************** See what's new at http://www.aol.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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