I'm thinking that the IF transistors have weak gain, even though the voltages measurements closely match the schematic. Seems that every portable transistor radio I run into has weak volume. Any other ideas?
Let me know if I am right...I just can't stand being wrong......lol
:Just wanted to bounce this idea off Edd or anyone else; even after realignment, the volume is still very low at maximum volume despite fresh batteries and new output and driver transistors (and a germanium diode detector). All electrolytics were replaced and out of tolerance resistors replaced. (Third IF transformer had an open secondary, which I repaired.)
:
:I'm thinking that the IF transistors have weak gain, even though the voltages measurements closely match the schematic. Seems that every portable transistor radio I run into has weak volume. Any other ideas?
:Try a different speaker.
:
:Let me know if I am right...I just can't stand being wrong......lol
:
:
::Just wanted to bounce this idea off Edd or anyone else; even after realignment, the volume is still very low at maximum volume despite fresh batteries and new output and driver transistors (and a germanium diode detector). All electrolytics were replaced and out of tolerance resistors replaced. (Third IF transformer had an open secondary, which I repaired.)
::
::I'm thinking that the IF transistors have weak gain, even though the voltages measurements closely match the schematic. Seems that every portable transistor radio I run into has weak volume. Any other ideas?
--C8 (2000pf) at volume control might be shorted.
--earphone jack may be dirty.
--K1 network defective.
--C9 (4700pf) may be shorted.
::
:::Just wanted to bounce this idea off Edd or anyone else; even after realignment, the volume is still very low at maximum volume despite fresh batteries and new output and driver transistors (and a germanium diode detector). All electrolytics were replaced and out of tolerance resistors replaced. (Third IF transformer had an open secondary, which I repaired.)
:::
:::I'm thinking that the IF transistors have weak gain, even though the voltages measurements closely match the schematic. Seems that every portable transistor radio I run into has weak volume. Any other ideas?
::The speaker had high output during realignment. I also tested the speaker when I first took the radio apart, so I'm sure it's ok.
::
:::Try a different speaker.
:::
:::Let me know if I am right...I just can't stand being wrong......lol
:::
:
:
:--C8 (2000pf) at volume control might be shorted.
:--earphone jack may be dirty.
:--K1 network defective.
:--C9 (4700pf) may be shorted.
:::
::::Just wanted to bounce this idea off Edd or anyone else; even after realignment, the volume is still very low at maximum volume despite fresh batteries and new output and driver transistors (and a germanium diode detector). All electrolytics were replaced and out of tolerance resistors replaced. (Third IF transformer had an open secondary, which I repaired.)
::::
::::I'm thinking that the IF transistors have weak gain, even though the voltages measurements closely match the schematic. Seems that every portable transistor radio I run into has weak volume. Any other ideas?
I think that if that was my unit to further evaluate, I would sub in audio at the high end of the volume control in order to see exactly WHAT the optimum in volume level and clarity of produced audio that the present state of the audio chain is capable of reproducing.
Nothing better to use as a discriminating audio program test source than that from an audio CD or just the audio out from a DVD player. The output matching Z from either above sources is a bit higher that you would be encountering in your units frontal AF stage design , but without going into the building up of a proper Z transsitional pad, I certainly think that at the quality level of that old "geranium" technology in your sets design, that another very simple dodge might be in order.
Just get yourself a 5 to 10 k pot...carbon..even linear taper is ok here..and it then has its outer terminals wired and going over and shunting your units volume control and the incoming Test audio line has its ground connection to the low side of the volume control and the "hot" audio line gets coupled into the center tap of the new control thru an isolative .1 ufd... or higher.. paper/mylar/poly cap. That then should let you incrementally advance the AF input with the coupling pot and just see the audio quality, along with the loudness before distortion that the system can reproduce.
If you find that resulting sound to please you, then it would be a matter seeing if your current fallacy is not enough detected audio produced by the front end RF circuitry up to the AM detector diode..... OR.... the whole audio chain after the detector diode is a bit deficient in its overall gain.
An evaluation of that nature will be requiring an audio generator, AC voltmeter or scope.
Zuj'ing for feed back.
73's de Edd
Hmmmmm....a hacking in and getting the routing and specific URL numerical identifier ...reveals Peanut Gallery to be none other than........
You may recall that all transistors from the detector to the output were replaced. Incidentally, the output does get loud during alignment, so I don't see how the output could be the culprit. I'll try your suggestion before I replace the mixer and IF transistors.
:Good grief !.... (a la Charlie Brown).......Sir Mark, we thought that you had fixed that unit and was bopping off down the freeway, with it hard pressed into your left ear, and attaining a high state of nirvana whilst listening to its golden oldies, still well retained in its circuitry after all of those years past.
:
:I think that if that was my unit to further evaluate, I would sub in audio at the high end of the volume control in order to see exactly WHAT the optimum in volume level and clarity of produced audio that the present state of the audio chain is capable of reproducing.
:Nothing better to use as a discriminating audio program test source than that from an audio CD or just the audio out from a DVD player. The output matching Z from either above sources is a bit higher that you would be encountering in your units frontal AF stage design , but without going into the building up of a proper Z transsitional pad, I certainly think that at the quality level of that old "geranium" technology in your sets design, that another very simple dodge might be in order.
:Just get yourself a 5 to 10 k pot...carbon..even linear taper is ok here..and it then has its outer terminals wired and going over and shunting your units volume control and the incoming Test audio line has its ground connection to the low side of the volume control and the "hot" audio line gets coupled into the center tap of the new control thru an isolative .1 ufd... or higher.. paper/mylar/poly cap. That then should let you incrementally advance the AF input with the coupling pot and just see the audio quality, along with the loudness before distortion that the system can reproduce.
:If you find that resulting sound to please you, then it would be a matter seeing if your current fallacy is not enough detected audio produced by the front end RF circuitry up to the AM detector diode..... OR.... the whole audio chain after the detector diode is a bit deficient in its overall gain.
:An evaluation of that nature will be requiring an audio generator, AC voltmeter or scope.
:
:Zuj'ing for feed back.
:
:73's de Edd
:
:Hmmmmm....a hacking in and getting the routing and specific URL numerical identifier ...reveals Peanut Gallery to be none other than........
[[[ Incidentally, the output does get loud during alignment, so I don't see how the output could be the culprit. ]]]
True, your sets attainable max AF OUTPUT might seem adequate when using a modulated sig generator referencing, and that being at what signal level
...999 microvolts ..or ...9,9999 microvolts ??, but your sets RF circuitry up to the detected AF sourcing may not be able to attain that same level of detected audio with the off the air signals received.(CAUTION / FACT..the subjecture of persons to a 400~ audio din/drone ,in excess of 1 hour, can have detrimental effects upon their sanity)
As one spot check on the health of your alignment, for my blind and mute referencing, will you fire up the system and let the transistors warm up (April 4th Fool...since the 1st was on a Sunday/Holiday) and then select a weaker station at the low end of the dial and grasp the winding of the loopstick antenna twixt thumb and adjunct fore finger...should space constraints preclude that possibility.. then, just press as much flesh as you can get up against its winding proper. Did the volume decrease, increase or have no noticable effect made on the sets volume ??
Next, do the same at a like level of signal at high end of the dial..with the same questioning as to its like volume affectation.
Resultant answers....
I have made a new markup, with the AVC circuitry loop of your unit being channeled in violet..fuscia ?
Schematic Ref:
http://img516.imageshack.us/img516/5976/arvinayveeceebusmarkupsk4.jpg
Notice that there are about 10 discrete components involved in that AVC loop with its origin being back at the detector and a routing forward, towards
the 1st IF amp.(The 2nd if stage runs at a fixed gain.) Initially, the volume control is DC loading the line and is stripping off of the AC AF audio
component at its wiper, then AVC has its passage thru an isolative/dropping/filter resistor R5 and then on to the AVC filter apacitor C1 and finally
to a bias referencing resistor R6 that is establishing the initial static biasing being afforded to the 1st IF amp xstr. The derived AVC voltage then
counteracts against this level, with a stronger detected AVC voltage being created, with any ever stronger AM stations signal level, thus, progressively
throttling back on the 1st IF stages gain, with the time constant of C1 affecting the overall attack/decay time . Thats the gist of the units AVC operation.
Just like a tube set, but working at a much lower Z, be leery of any of the components in that loop having an affect on that derived AVC control voltage.
Electrolytic C2 having leakage could be a factor if the volume control is on up in its max volume position. Check the tolerances of R5 and R6.. out of
circuit..oops.... chassis pull and rotate time. Also the leakage of C1.
Less suspect...(experienced reliability of type)... would be the ceramic caps of C8 filter and the inner couplate contained, C6A. As an evaluation of the
available gain that the system could attain , try tuning into a station that will give the most volume capable and then lift out R5 at its #9
reference point end, and then, after a few seconds of C1 stabilizing, you would then be running the system with out any AVC corrective biasing restraints.
A further test would be the use of an ~27K resistor in SERIES with lifted R6 (at its #9 connected end, not the 5.2 voltage sourcing). Evaluate the audio level on the reference station and then move and, use solely, that 27k from the 5.2 voltage source up to the #9 line).
If the volume still was not up to standards expected, I might now be wondering ? about the Betas of the IF strip xstrs, them being aged "geranium" units,
with some leakage/ Beta dampening factors, even from day one.
73's for now....Edd
---------------------Delineation----------------------
:Yes, I thought sure I would be enjoying this set by now. Since I've come this far, I'm determined to see this through.
:
:You may recall that all transistors from the detector to the output were replaced. Incidentally, the output does get loud during alignment, so I don't see how the output could be the culprit. I'll try your suggestion before I replace the mixer and IF transistors.
:
::Good grief !.... (a la Charlie Brown).......Sir Mark, we thought that you had fixed that unit and was bopping off down the freeway, with it hard pressed into your left ear, and attaining a high state of nirvana whilst listening to its golden oldies, still well retained in its circuitry after all of those years past.
::
::I think that if that was my unit to further evaluate, I would sub in audio at the high end of the volume control in order to see exactly WHAT the optimum in volume level and clarity of produced audio that the present state of the audio chain is capable of reproducing.
::Nothing better to use as a discriminating audio program test source than that from an audio CD or just the audio out from a DVD player. The output matching Z from either above sources is a bit higher that you would be encountering in your units frontal AF stage design , but without going into the building up of a proper Z transsitional pad, I certainly think that at the quality level of that old "geranium" technology in your sets design, that another very simple dodge might be in order.
::Just get yourself a 5 to 10 k pot...carbon..even linear taper is ok here..and it then has its outer terminals wired and going over and shunting your units volume control and the incoming Test audio line has its ground connection to the low side of the volume control and the "hot" audio line gets coupled into the center tap of the new control thru an isolative .1 ufd... or higher.. paper/mylar/poly cap. That then should let you incrementally advance the AF input with the coupling pot and just see the audio quality, along with the loudness before distortion that the system can reproduce.
::If you find that resulting sound to please you, then it would be a matter seeing if your current fallacy is not enough detected audio produced by the front end RF circuitry up to the AM detector diode..... OR.... the whole audio chain after the detector diode is a bit deficient in its overall gain.
::An evaluation of that nature will be requiring an audio generator, AC voltmeter or scope.
::
::Zuj'ing for feed back.
::
::73's de Edd
::
::Hmmmmm....a hacking in and getting the routing and specific URL numerical identifier ...reveals Peanut Gallery to be none other than........