Here's a link to a prime example:-

http://www.electronicstrainingcentre.com/Images/Resources/ResistorColourCodeHD.jpg.

Yours is 4.7kΩ.

PS was going to post last night but was getting 500 internal errors on this site...wasn't sure what was happening as up here atm we have NBN being rolled out in both flavours I think so the nets been real screwy.

See comment in General Discussion. For some unknown reason the site simply wasn't behaving itself. The narrow version of the site and all other hosted sites worked perfectly. Rebooting the server fixed up whatever was causing the vapour lock.

With resistors, there are usually four bands, 1st band is the first digit of the value, the second band being the second digit, the third band is the multiplier code and the fourth (which can be ignored for old radios) is the value tolerance. So yellow is 4, purple is 7 and red is 00. Gold is [gold]5%[/gold] tolerance and is the most common type.

Gee That was a real Doh moment there *faints*

I aint colour blind and have been reading resistor codes for years since the 70's but I think I am getting dyslexic...(ok there was kinda 10 year break 2004 up) still thats a major error on my part
(the 5 band 1% 2% confuse me but E12 24 shouldn't have)

I dont know how I made that boo boo, constant interruptions dont help thought...long story

Still the original question applies

"Would a plate resistor in circuit like this be so low in value ?"

I'll edit The post Brad noting My error and a correction...it does measure 4K7 thought I just checked it

Thanks again Brad

Yeah rather strange but servers I've no idea on ..computer gremlins well 'veI met a few of them and most I've never found a definitive answer for

Cheers mate

Don't worry too much - I often have to refer to a code table like the one linked as I forget the colours too. When I was a kid, assembling kits from Dick Smith Electronics, Bill Edge Electronics (what is now known as Jaycar) and Tandy, I knew them a bit better.

Pins are read clockwise looking at the base of the valve, or the wiring side of the socket.

6AN7 and 6BE6 are apart from having a different number of pins, totally different animals. 6AN7 has a separate exciter in the form of a triode and its grid is also internaly connected to grid 3 of the hexode.

Pin 7 is the plate of the hexode, which I would expect to go to IFT1 with no plate resistor. (not looked at circuit yet) 250V B+ I would expect around 33K on the plate of the triode (pin8) and 47K on the osc grid (pin 9) [Philips data].

Chants webpage is not coming up. Internet has been hopeless lately.

I have had a set where the audio was one year & the RF another??? Factory runout model.

Marc

I just visited his site. The site's account is there but not the pages.

Does anyone know if he's just renovating or is he retiring the site?

Refer comment in discussion. I think the issue is the Internet system falling apart.

Thanks Brad but it was dumb mistake I shouldn't have made, I do think I have some strange form of dyslexia thought and its only happen since I started taking pills to keep me living healthy LOL (cholesterol and I am diabetic its seems now)

Gee Kevins site was there when I posted the links but seems the sites Awol
I did have problem with the docs loading from site and had to always download them and look at them from the download
(I just blamed it on firefox doing thing differently or maybe more likely what it links to for pdfs)

Thats kinda funny (strange) considering we were talking about placing a docs section on this site.. Brad

I can send the pdf's to you marc if you like (hoping your email wont do stupid things like limit size or dump the email in the trash like happen to me with GTC email..I felt terrible about that but he was right thats were it went)

Marc the Valve in question is the 6AV7 detec etc, I did check the pins in relation to what hangs off them but thank you for the "Clockwise wire side" I'll try to etch that in stone in my memory box....I do have to keep checking myself when chasing out circuits

Anyway the query really was that I wouldn't expect such a low value there and both circuits do have it as hundreds of K... 270K and 220K

The "But" in this is there are differences within this circuit to both the 64 and 65 schematics

Sadly I am not well versed in valve radio circuits to ferrite this one or hazard a guess
It just seemed too low a value for a plate resistor in my uneducated mind

Still the idea of someone making a mistake dont wash either as it a 4K7 and not a 2K7 that would have made more sense to a mistaken value...but then again theres me lol..who writes 2K7

As I said it actually works so maybe it is right

Maybe the clues in what the Back Bias is actually feeding...anyway thanks for taking the time to respond I do appreciate that

I think I will chase this circuit out and fully document the differences I find

Funny you mention that Marc as I remember being told LE holden were hybrid years the front or back was the earlier year and the other the later new model year ...

This radio version does have that element to be sure

6AV7 does not to my knowledge exist. If its HMV it will be a cranky little 6AV6 double diode triode.

If they used it as a voltage amplifier it if the set is not back biased have a very high cathode resistor around 5K and a plate resistor around 470K Grid 1M

Otherwise in 61-51 270K plate grid 10Meg & No cathode resistor. The Plate resistors & grid resistors on them have an attrition rate. I see resistors similar to this. 10M will be the grid & 2.2M part of AGC.

Do need to see the circuit for yours. Often these (and others) use feedback from the secondary of the OP transformer. The number of those I see stuffed up is incredible. One of two things or both happen.

The transformer is inverted and the wrong phase ends up producing the wrong voltage & it oscillates, or, similar to the tapped pot on the KJ Astor, in work here (ready to check & test). It gets disconnected. In many cases that alone will cause quality issues with the output signal.

6AV6 & any 1st Audio in that setup, has to provide enough signal (in the form of voltage) to drive the 6M5.

Marc

Kevins site is back up (and the docs seem to be loading now to me as they should)

Geez I am not winning the battle with Typos in this thread .. again my apologies...your right!

it is indeed 6AV6 as you said Marc

I am going to have to draw out the circuit as best I can but it definitely seems to be a mixture of both the 64 65 Circuits...with differences from what I can tell (at the lest in regard to Back Bias )

Yes you are right it does feedback from the secondary (speaker side) of the output transformer to the 6M5 (if this is what you mean)

From the schematics

The 64 does this via a 25 μF capacitor (C20) to pin3 (cathode) of the 6M5 and a resistor (R12) 220K goes to ground

The 65 circuit just has a wire from the transformer secondary to pin 3 (cathode) nothing connection to GND or anything else

In this case of pin 3 mine follows the 65 circuit, if you look at the last photo you will see a yellow wire trailing off to a hole which it then connects to the Output Transformer secondary

(Edit 6M5 pin 3 = Cathode & Grid No 3, arh that makes a little more sense)

Seems I'll have to watch this point "phasing" when I replace the 62's output transformer (this does use a cap as above marked C22)

Anyway Marc thanks again for the help

I'll see if I can cobble a half decent schematic together of this particular radio version as I am sure its probably not the only one out there and may save headaches for others

As I said, it does work apart from the intermittent issue but the resistor value got me real curios as to if it was right...still other checks etc need to be done... its far from finished yet

Original Schematics of Little Nipper Model 64 (fitted with 6BE6) and 65 (6AN7)

The version I have seems to be a hybrid of both (with changes)

The pdfs are 64, 65 and my partial redraw of the 65 circuit

HMV Little Nipper 64 Circuit Diagram
HMV Little Nipper 64 Circuit Diagram

Edit after a further look there may be more differences then I thought, at lest physically in location..how that plays out electrically not sure yet

Partial redraw of schematic with what in my version, this is a work in progress and by no means complete

HMV Little Nipper 64 Circuit Diagram

Thanks Brad

the components marked in red are what exits in this nipper

Also when I redraw I put some breaks in some links where as the original just crosses over each other and uses dots for connecting points
(just be aware of that thats all..it does connect to the other side)

Thanks all

Just a Foot Note on that intermittent Fault

I am not sure if it is solved but it seems to be working a lot better in regard to it
(without going into details of what I tried)

What I found was that a Mica Cap had been connected to the Dual Gang Tuner but was never soldered to the tag
Not sure which part of the circuit that related to, I've shelf this one while I get back to the other nipper...I now have an output transformer...anyway heres hoping its resolved.

Cheers All and Thank you