Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

*COMPLETED* simple S meter? for a minerva tropic master
#1
Tongue 

maybe i need to do sum searchin eh before i post?   
Naw,, me thinks ill be a brat Icon_smile

I have me a minerva tropic master and armed with some notes i took from a member about how to hand make a BFO , i jumped in.
i quickly realized i dont like my note taking , so i move over to exploring a S Meter mod to this set.

although i know there is a few generation gaps for me to catch up with to get better at working on this tech, i am trying real hard.  My RF skills are all be zilch,  i mean i understand how all this RF stuff operates, i just dont have the experience to understand how it works if that makes sense.  its just like mux / dmux digital tech but on an analog form with all kinds of parts on either end specific to RF.  Ive never had a job where RF was something i visited often enough to end up needing to "know it" well.


when things like this happen to me, i tend to adapt in different solutions that involve using techniques i already know.

Adding an Smeter to my minerva was explored for a few hours last night.
i went in thinking about what i know.
i know :
--that when we tune , signals become stronger or weaker.
--RF signals with respect to the reference IF are being detected, and amplified, passed on down to the speaker.
--the speaker is nothing more than a wound up coil of wire and or an integrated magnet reacting to the signal that was previously amplified.
--there must be a few terminations that are constantly changing in voltage with respect to the peak to peak amplitude of the signal being compared to the IF.
-- i know that as you turn the tuner knob voltages must change.
--an smeter could be described in a basic conversation as nothing more than a meter bridged across a shunt tow which the shunt is constantly bombarded with varying really super low voltage like mili volts.


at this point i have found in the minerva at least six terminals that vary in voltage.
I also found that at my speaker, the mv readings are monitorable.  ive noticed that with the volume set to a reasonable level, for this set it seems that around 20mv means "nothing is there".  When there is  a station, the mv reading could be around 50mv on a weak signal to as much as 500mv on a strong one.
i took my readings with both a analog meter and a digital one and the act of inserting the meters across the speaker had affect on signal reception or audibility.  this got me to thinking................ of something i already know i can do to build a decent Smeter.

I want to tie a millivolt meter across the speaker as a visual indicator of signal strength.


a few links i am using as the "style" i would like.
this must be small
must be a millivolt meter 0-500mv or 0-500-0 etc


this one goes only to 100mv,, i know that strong stations and depending on my vol knob,, it would max out and peg most of the time.
https://www.ebay.com/itm/0-100MV-2A-MILL...Swxu5ZJAvn


is there a place i can buy a analog millivolt meter with a wider measurment range?

should i just buy a 10$ cheapy analog meter and gut it and re-box it and make my own by setting it to the proper scale then mount and call it good.?





Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
12' Philco
If it is 12', either Kareem or Andre would have to jump pretty high to look at the front panel. Kareem would have an e...morzh — 01:48 PM
12' Philco
And here's a story about the tires on the truck. Same "no-stoop" guy must have installed these! Take care a...GarySP — 01:17 PM
Hickok AC51 tube tester
I think they have only shown the secondaries of the transformer. Two of them feed the rectifiers' filaments.morzh — 12:58 PM
IF can wire size and Rubber mounts?
Arran If the wire inside cans is the gauges you mentioned, the sole reason for that would be mechanical, to stiffen t...morzh — 12:56 PM
12' Philco
Rod, Yes, I know, but the Giant Philco is not around anymore either, so I go by whoever was alive fairly recently. H...morzh — 12:54 PM
Hickok AC51 tube tester
Absolutely no one is going to reverse engineer that circuit. Even the iron core is missing.RodB — 10:37 AM
IF can wire size and Rubber mounts?
Thanks to both members for your help regarding wire and tuner mtg supports. regards--Johngeorgetownjohn — 09:33 AM
Hickok AC51 tube tester
Note that no power cord, power switch, or power transformer switch are shown. That (along with my experience with full s...DaleHCook — 07:09 AM
IF can wire size and Rubber mounts?
A pair of wire strippers can give you an idea of what the existing gauge of the wire leads are in the IF can, I think it...Arran — 06:07 AM
My last cabinet for this year
Hello Dan, That is really beautiful what great looking radio you have ! I have friends who live in Calgary and the wea...radiorich — 01:51 AM

[-]
Who's Online
There are currently no members online.

>