Re: Replacement meter has fsd current about three times old damaged meter.

On Jul 27, 10:17 pm, Gnack Nol <mchozfcesuj...@xxxxxxxxxxxxxx> wrote:
On Sun, 27 Jul 2008 08:24:12 -0700, terry wrote:

some deleted:

Have replacement meter (said to be from a Heathkit) approx same dimensions
which mechanically fits perfectly; but has an fsd of about 100 microamps
(I think) whereas the old damaged one appears to be about 30 microamps
fsd.

Idea is to fit a small DC amplifier mounted on a piece of vero-board etc.
inside to amplify the DC signal that comes through the range and FWD/REV
switch from the probes.

more deleted:

Terry you should check to see if the meter circuit contains a shunt and if
so try adjusting it for the coser to the proper range. If you can obtain a
movement that is identical except for the scale the original meter face an
probablt be placed on the working mechanism to render a more original look.

Using an amplifier in a sensitive circuit like a swr bridge is problematic
since the amplifier itself will respond with frequency sensitive gains.

You might want to go to some of the surplus sites that still do exist like:

Fair Radio Saleshttp://www.fairradio.com/

American Science and Surplushttp://www.sciplus.com/

Thank you for the comments. Re. frequency senistivity. No think that
enters int it?
The unit has two sensor, that look like diodes mounted in cavities in
the brass silver plated transmission line of the unit. The ouputs of
the diodes are connected to a 6 position switch. Three FWD. and three
REV. power positions. The output of the switch is just two unshielde
short leads to the meter iteself. There is also a tip/ring headphone
style jack on the side of the unit which disconnects the internal
meter and extends the circuit so it can be read by a remote or
external meter. So at that stage believe everything 'after' the sensor
diodes is low current DC. So it would appear necessary to amplify the
DC micro-voltage/current by about 3 to operate the replacement meter.
BTW tempoarily arranged the existing (damaged) meter (disconnected
from the unit) and the replacement in series with a low voltage source
and a varaible resitor. With the old meter at (as far as coule be
judged due to the damage) at full scale the replacement was about 0ne
third. Haven't measured the DC resistance of each yet because that
might have an effect on whatever circuit is used to 'step uop' the DC
current to operate the meter.

.

Relevant Pages

  • Re: Little things that show someone knows how to play the game...
    ... At high levels I hope. ... I don't buy different sets of gear but I start developing different ... There's more to effectiveness than raw damage. ... I always have a meter running, primarily to gauge my own effectiveness ...
    (alt.games.warcraft)
  • Re: whats with all the talk about "Kara" ?
    ... while still coming out with good damage at the end of the day. ... damage meter, ... no reason to not use a threat meter. ... and the DPS deficiency may result in a wipe. ...
    (alt.games.warcraft)
  • Re: Frequency Measurement with a DMM
    ... > In the Measuring Frequency section of the user's manual, ... > exceeds 250 volts AC rms, you might damage your meter and expose ... > "Input sensitivity: ...
    (sci.electronics.basics)
  • Re: Power problem
    ... I am more likely to cause more damage than fix anything. ... Using a multimeter is about the least dangerous task. ... Why use the meter? ... to use as a hammer. ...
    (microsoft.public.windows.vista.hardware_devices)
  • Re: Which damage meter mod to use?
    ... heard there is a problem getting pet damage added to hunters (and ... I don't use a damage meter, but Omen is a great threat meter. ...
    (alt.games.warcraft)