Bush TR91

[Paul_RK]

Originally Posted by Heatercathodeshort

...I think Roberts used the PP10 in one of their models [RT1?]. Customers used to bring them in for repair not realizing that it was powered from a battery! It lasted ages, years in some cases used only an hour a day. John.

The published company history includes that report about the RT1, but its battery was a PP8: 6 volts, three (or was it four?) PP1s in parallel inside, with the same snap connectors as the PP1/PP9. Later examples of the RT1 include a wooden turnbuckle to secure a PP1 in place for users who preferred a less heavy radio at the expense of battery life.

I'm not sure the PP10 existed quite in time to have been an option for the RT1, but it was used in a couple of Roberts' later and larger portables, the RT7 and RT8.

Paul

[high_vacuum_house]

I have been following this thread with interest and spotted an unrestored one at the NVCF on Sunday for £5. As the construction looked particularly interesting I picked it up for a restoration even though transistors are not really my thing. Looking forward to restoring this.
Christopher Capener

['LIVEWIRE?']

I;ve never owned one of those Battery-only Table radios, and in fact it's years since I've even seen one. I wasn't particularly thinking of, or looking for, sets of that type, at the NVCF yesterday, so there could have been some there. Between 1955 & 1966 I lived in an old house with no mains electricity or other modern facilities. At different times we had a HMV Table Radio, can't remember the model no, which ran from a 120v Dry battery and 2v Accumulator, and two different versions of the Ever Ready Sky Queen, which used the B136 90v + 1.5v Dry batery. The Sky Quen's don't really qualify as 'table Radios', as, IIRC, they had handles, plus of course, they used the '96' range of valves. AS has no doubt been pointed out before on this forum, because radios cost at least the equivalent of £300 in today's money, they were looked after, and repaired when they went wrong, and I guess most households only had one radio, too.

[Cobaltblue]

Thread re-opened as requested.

Cheers

Mike T

[AD360 Rob]

These are a great set and one of my personal favourites. Mine came via eBay (can't remember how much it cost but it wasn't a lot) and all that was needed was a quick squirt of servisol and a new detector diode (the one that lives in the final I.F transformer. It's doing sterling duty as my bedside set although there is a noisy transistor in the amp that I will get around to one day.

I hope you enjoy using it.

[Restoration73]

I have the Ferguson 626 BT model which originally used a PP10. The set performs well
on MW/LW but FM sensitivity could be better. Running on a 6 x C cell holder.
I also have a National AB-361 which has MW and 2 x SW. It is unusual that it uses
Mullard transistors OC45,71,76, and OA70, and 2 x MC102. Not sure of the date.

[sexton_mallard]

Originally Posted by AD360 Rob

These are a great set and one of my personal favourites. Mine came via eBay (can't remember how much it cost but it wasn't a lot) and all that was needed was a quick squirt of servisol and a new detector diode (the one that lives in the final I.F transformer. It's doing sterling duty as my bedside set although there is a noisy transistor in the amp that I will get around to one day.

I hope you enjoy using it.

Thanks Rob. This is one of my favourite sets and it gets a lot of use. Recently it has developed a distinct hiss and power consumption has gone up to 30 mA from about 15mA. The hiss does not change with wavechange or volume which also leads me to the audio stages. I started by disconnecting C31 and the hiss did not drop noticeably. I then started checking TR4 and TR5. Voltages seem close to spec and the transistors appear to check OK in the component checker. Resistors and caps appear to be OK apart from C35 which tested low and was probably dried out. For the craic I substituted a ZTX500 in place of TR4...more gain but no change to hiss or power consumption. I put the OC71 back and then substituted TR5, a metal jacketed OC78D with the ZTX500 PNP transistor...still the hiss but more gain and some amusing instability with bass notes going 'booooing' in a reverb effect as I guess the biasing is too low for this Si transistor. Again, the original germanium transistor has been returned.

So I am a pit puzzled as the hiss goes right down if I disconnect the signal path between TR5 and the phase splitter transformer T1. I can't see how TR6 and TR7 are the culprits. I will double check the resistors and caps...

In other words the problem seems to be in the region of T4 and T5 but the transistor substitutions made no difference.

[Restoration73]

Agree on the great styling, forgot to mention. Concentric tuning and volume not often
seen, the only one I have like that is the Ferguson 3146 portable "woodie" set.

[sexton_mallard]

After conceding one of the OC78s was leaky in the output stage to the tune of 10-15mA I went digging through a lucky box of assorted components and found a OC45 and a OC75. I clipped them in with jump leads and hey Presto! Good sound quality with minimum hiss and a total current draw at normal volume back to about 11 to 15 ma. Not exactly a matched pair but my ears says they are!