HMV 1124 - Has Been Tested And........

[Terry]

I would try adjusting the aerial trimmer.
It should be shown on the circuit diagram and may be accessible from the rear of the chassis for adjustment during installation of the set.

That could be the wrong answer because we don't know what frequency is being received!

Fine if it is at the high frequency end of the band but if it is at the low frequency end it will be the aerial coil core/ferrite rod/padder* which will need initial attention.

Alternatively, the aerial circuit alignment could be spot on but the local oscillator is way off the mark.

It will be necessary to find out exactly what the situation is before offering advice - the wrong advice will only complicate matters! 

* We don't, as far as I know, have a Model Number for this set yet, so it is impossible to know which of the three options applies.

CORRECTION We do, in fact, have the Model No.: 1124 which is covered by Trader sheet 987. This means that it is the core which should be adjusted.

Mods: Can the heading of this thread be changed to include the Model No.?

I'm sure that, after seven pages of this thread, I'm not the only one who is losing the plot!

[Mark Hennessy]

Mods: Can the heading of this thread be changed to include the Model No.?

Good idea...

[Refugee]

The trimmer is either a core or a cap depending on the model.
Perhaps I should have said aerial tuning.

[pwdrive]

Some receivers have a separate antenna tuning capacitor as a user adjustable, RCA , Hallicrafters comms receivers spring to mind.....Any domestic examples apart from early TRFs ? (not car radios)

Lawrence..

[Terry]

The trimmer is either a core or a cap depending on the model.

No, well not to my way of thinking, at least ...

A trimmer is a trimmer is a trimmer and (primarily) affects the HF end of the band.

The device that affects the LF end of the band may be a core or a variable capacitor,  the function of which is traditionally known as a padder, although it physically resembles a trimmer (but has a much higher capacity).

The term 'padder' seems to have fallen out of use since the widespread introduction of adjustable cores because referring to cores and trimmers still clearly defines the difference between the two functions.

Perhaps I should have said aerial tuning.

Perhaps you should but, as I said in my previous post, we have not determined whether the aerial or oscillator circuits require attention, so you would still be jumping to conclusions which might not be justified and, more importantly, confuse the OP.

Some receivers have a separate antenna tuning capacitor as a user adjustable, RCA , Hallicrafters comms receivers spring to mind.....Any domestic examples apart from early TRFs ?  (not car radios)

But not this one, Lawrence!

[Refugee]

I doubt the aerial tuning would affect the mixer that much because the output impedance will only change very little as it is adjusted.
It is just a stand alone unit between the aerial socket and the mixer.

[pwdrive]

The trimmer is either a core or a cap depending on the model.

No, well not to my way of thinking, at least ...

A trimmer is a trimmer is a trimmer and (primarily) affects the HF end of the band.

The device that affects the LF end of the band may be a core or a variable capacitor,  the function of which is traditionally known as a padder, although it physically resembles a trimmer (but has a much higher capacity).

The term 'padder' seems to have fallen out of use since the widespread introduction of adjustable cores because referring to cores and trimmers still clearly defines the difference between the two functions.

Perhaps I should have said aerial tuning.

Perhaps you should but, as I said in my previous post, we have not determined whether the aerial or oscillator circuits require attention, so you would still be jumping to conclusions which might not be justified and, more importantly, confuse the OP.

Some receivers have a separate antenna tuning capacitor as a user adjustable, RCA , Hallicrafters comms receivers spring to mind.....Any domestic examples apart from early TRFs ?  (not car radios)

But not this one, Lawrence!

I wasn't referring to the receiver in question, obvious really.

I don't dig the exclamation mark either.

Anyways that last post of mine was also asking a question in general, that's not unusual in a lot of threads on this forum.

Lawrence.

[Nowhere-Man]

Mods: Can the heading of this thread be changed to include the Model No.?

Good idea...

Yes, please feel free to edit the heading if this is so desired for clarity. I have posted the model number a few times because there was another thread on the same theme. If I understand correctly there was more than one model number to include exported sets but overall the circuit diagram can be found online.

I tend to have my very lazy days when I do no work at all on the radio and may just play my electric piano and then inevitably I resume work.

I'm now pretty confident it will be a relatively happy ending with this set. I must admit the best information I got here was the lamp limiter we discussed a few months ago when I first joined. I can definitely vouch for fact dim bulb testers are the best thing since sliced bread. The funny thing is when I first made a simple device, it never glowed ever but, on this HMV, it did indeed glow. That had me kind of worried. Later on, I found if the glow is just an orange tint, you can apply full power so long as there is no bright glow from the lamp.

Anyway, it does seem to be "bedding down". The dim bulb tester no longer hardly shows an orange tint. The voltages (full voltage now) now also test closer to the schematic, almost bang on.

I'll be checking all the aerial connections. I did straighten out the socket pin the other day but now I'll have to make sure the connection is going right to the Mixer Tube. Some of the bases are a bit "wobbly" and I'm going to have to do some serious work on the waveband switch.

To clarify, yes, it would have been the IF anode I located and not the L.O. anode. This should be somewhat lower on voltage.

It's 17.19 and I'll be offline by 17.45 (library closing).

Pics are now easily available as I can downsize on Paint.

[Nowhere-Man]

I doubt the aerial tuning would affect the mixer that much because the output impedance will only change very little as it is adjusted.
It is just a stand alone unit between the aerial socket and the mixer.

I'll keep you informed. I tend to have my own weird and wacky way of dealing with such issues, given I tend to use the situation in itself as a learning exercise. So, I'm looking into the whole Local Oscillator and Mixer circuit both on this set and how it also relates to other sets. Sor t of bang in a bit of theory with an actual set to relate to.

The schematic on this set does show a very heavy going meshwork of switches and coils with trimmers and padders and so forth. HMV went to town on this in a big way. There is even a gram switch and speaker "off" switch apart from the multiple trimmer switches and even image rejection switch and so on and so on.

All the suggestion here will be included in my work. I'll be checking there is indeed a decent aerial feed to the grid and also any HF caps and so on. As well as the rotary switches which are pretty grim even after cleaning some weeks ago.

I did think maybe the Mixer tube was suspect but now feel almost certain I'm looking at worn and tired circuit connections. Given every single scale lamp is dead and O/C, you can see most of what is wrong is down to ravages of time.

P.S. thanks for all your positive comments in the course of this thread

[Terry]

I doubt the aerial tuning would affect the mixer that much because the output impedance will only change very little as it is adjusted.
It is just a stand alone unit between the aerial socket and the mixer.

Let's recap ...

The set appears to have low gain.

When a signal is injected directly into the mixer's anode circuit via the meter lead, thus completely bypassing the aerial tuning arrangements, the gain increases.

This suggests there is an alignment problem but whether it is the aerial coil or the oscillator coil - both will cause the same problem if they are not tracking properly - we don't yet know.