Bush VHF61, my first restoration attempt.

[Bassette]

Multimeters . I do hope I am not asking too much again. I have watched the Best Tutorial and understand most - but when I come to measure resistance of my new capacitors or my skin - things do not happen as per the tutorial. I turn to the horse shoe sign OMS without touching anything the display shows 1. I then touch each side of a new capacitor with the pins, no changes occur, same number 1 in the display. A good 9 volt battery is well charged
in the meter?

[Steve_P]

Dead right. The horseshoe means the meter is on the Ohms range. If you touch the two probes together, you should get a low reading.

If there are several ohms ranges, then you need to turn up and down to measure Ohms, Kiliohms, etc. Don't put any voltages on the probes in the Ohms ranges.

Cheers,

Steve P.

[Bassette]

Hi Steve
Tried different ranges in the Ohms - no change just a number one stubbornly remains.

As I turn to different ranges the decimal dot moves away from the number 1 and comes back as I turn the other way?

Strange or what?

[ThePillenwerfer]

A capacitor is, in theory at least, an infinite resistance to DC. When we talk about them leaking it means that the DC resistance is less than infinity, ie a 1 at the left of the meter. Large one will show a lower resistance which raises as it charges.

- Joe

[Station X]

Try connecting the meter leads together and see what reading you get. Make sure the leads are plugged into the correct sockets. Some meters have a separate socket for current measurements.

When measuring resistance with a DMM there are two special cases.

There first is "open circuit" which you can simulate by making sure the test probes or croc clips are not touching one another. Or you can remove the leads altogether. DMMs differ in how they display open circuit conditions. Fluke meters for example display an 'L'. Your meter would appear to display '1'.

The second is "short circuit" which you can simulate by connecting the test probes of croc clips together. You should get a reading of 0 ohms or close to it.

When posting resistance readings on here, never use the expression "no reading" it's confusing. Say "open circuit" or "short circuit".

It's also important to state units, so 47 ohms, 68R, 6.8K, 2.2M etc. Never just 5 for example.

Try measuring some resistors in your set. You don't need to disconnect them, but make sure the set is switched off.

[Bassette]

Hi Graham

This advice has done the trick. I now have things working - thank you so much.
Sticking pins into all parts and getting values, with the power off of course!

[Bassette]

Tool kit

Would nut spinners have a use in radio restorations?

[Herald1360]

Undoubtedly. However, they are more in the "nice to have" than "must have" category. I find a few BA miniature open ended spanners and a cheap 1/4" drive BA/AF/Metric socket set cover pretty much every situation. Add a small adjustable perhaps.

Some cheaper nutspinners have very thick socket walls which restricts their use in some places.

[Hybrid tellies]

Originally Posted by Sideband

However don't forget you need an aerial for VHF, preferably a proper dipole but you should be able to receive something with just a piece of wire about two feet long if everything is OK. If not then try a new ECC85


Rich.

Living just outside Bath my Bush VHF61 just about picks up the stronger local FM stations,from Mendip or Dundry, just on its internal aerial, and I have not done any work on it. Thanks to the local FM transmitter at Bathampton much of Bath enjoys good FM reception but of course there are a few black spots where FM reception is not so good.

[Bassette]

Hi Simon

I live just across the river from Bathampton until now I was not aware that we had a transmitter so close. Yes I do receive a strong FM signal now I know why.

Metric sizes what I wonder would be a 2 BA in metric.

Terry

[Station X]

2BA is 4.7mm diameter, so M4 will be smaller and M5 bigger. You'll have to replace the screw and the nut, as the thread forrms are not interchangable.

You can still buy BA fasteners from many online suppliers for example:-

http://www.emkaysupplies.co.uk/

[Herald1360]

Nearest metric to 2BA is M5. They are not exactly the same, though.

2BA thread od is 4.7mm vs 5mm

Nut across flats is 8.23mm vs 8mm

[Hybrid tellies]

Originally Posted by Bassette

Hi Simon

I live just across the river from Bathampton until now I was not aware that we had a transmitter so close. Yes I do receive a strong FM signal now I know why.

Metric sizes what I wonder would be a 2 BA in metric.

Terry

Ah you should have no problem, line of sight reception. On the Bush VHF61 which only goes up to 100Mhz sorry Mc's you should get a very strong signal from Radio 2 on 89.00Mc's, Radio 3 on 91.20Mc's Radio 4 on 93.40Mc's and Radio 1 on 98.60Mc's. The other outputs such as Classic FM Heart and Radio Bristol are all well above 100Mc's and probably beyond the tuning range of the Bush VHF61.

[Bassette]

Originally Posted by Hybrid tellies

The other outputs such as Classic FM Heart and Radio Bristol are all well above 100Mc's and probably beyond the tuning range of the Bush VHF61.

When I had my My Bush VHF 62 restored by a professional engineer I asked him about the possibility tweaking the range above 100Mhz. He looked at me as if I was mad! His reply came sharply " I would never do that - forget it!

[Bassette]

Progress update.
The soldering iron has been hot today! I have now replaced C65 and C67.
I looked at C66 and C68 but the challenge was too great at the moment, because the lip on the Outward Transformer hides these Capacitor connections. I have considered removing the Transformer from the Chassis to take a good peak at how things are connected - well at lest it would give me some confidence before I snip away blindly.

The radio is playing well and you might consider why I should continue replacing the
Wax C 66 or the Hunts C68. Opinions please?

Thanks. Terry

[Keith]

Originally Posted by Bassette

When I had my My Bush VHF 62 restored by a professional engineer I asked him about the possibility tweaking the range above 100Mhz. He looked at me as if I was mad! His reply came sharply " I would never do that - forget it!

It's really not a big deal to tweak the VHF 62 just above 100MHz so that Classic FM can be received. In fact the dial physically goes up to almost 102Mc/s.

[Steve_P]

I think you mean 'Output' transformer there.

Those caps should in theory be replaced. but I haven't on mine and it's OK. If you want to, then go ahead, but it the radio is working, then why go further than you have to?

As far as the tuning range goes, see if you can pull in Classic FM. Try tweaking TC2 slightly. (C7 on the Trader Sheet).

Cheers,

Steve P.

[Bassette]

Output it is!

Tweaking, I may not be ready for this but will read up on the pointers you have indicated.

I have now figured out where the wires go for C66 and C68 and successfully recapped them.

With your kind help I am beginning to gain a tad of confidence.

Terry