Hacker Sovereign RP25 - bathtime blues!

[Keith]

To avoid incessant Brexit drivel during my bath I thought I'd knock up a lead to feed my Hacker from an MP3 player. Outputs from MP3 stereo jack mixed via two 270 ohm resistors and resultant mono fed via 3.5mm mono jack to Gram input. This seemed to fit snugly but no output. Is there a special push button combination for Gram input or is the socket u/s? Help appreciated.

[Nuvistor]

Looking at the circuits for the RP25B and the RP25II, the gram input looks like a switched socket, I.e, disconnects the radio audio when a suitable plug is inserted into the gram socket.
Two thoughts, a dirty switch or the plug you are using is not compatible, seem to remember it needs a long shank, unfortunately I could also be thinking of the Hacker record players that required a long shank for the stereo extension.

[1100 man]

Hi Keith,
I did the same thing with mine, although it was for Radio Caroline fed from the computer. My jack was totally gummed up and needed some careful cleaning I seem to remember. As they are vertically mounted, they fill up with crud over the years.
Fed from a low impedance source like the headphone jack on a laptop, it just seems to mute any sound coming from the RF stages of the radio. Standard mono 3.5mm plugs work fine.

Hope that helps,

All the best
Nick

[Mike. Watterson]

Some of these older sets (maybe more Roberts than Hacker?) seem to need a longer 3.5mm jack than modern gear or indeed Japanese gear of the same era.

I use cheap CE marked "itrip" type gadgets to transmit FM from my Satellite Radio boxes or laptop or phone player. Some only have space for one cell, even though the chip needs 2.5V minimum so are distorted unless using the 5V in. In any case I use external power, either from sat box PSU, power plug or USB socket on something. The ones with no USB power out usually want 5V on the jack socket (3.3V LDO regulator inside). The ones intended for a car and having USB host to power a phone don't actually need 12V, 8V or 9V is fine. If you pay more than £8, it's too much. They all use one of two FM transmitter chips, either one programmed by I2C from the CPU under a blob of glue driving LCD and reading buttons, or else the one with preset PLL channels using a slide switch. Usually more channels are available than wired to the switch but some are 76MHz to 87MHz. I reserve the one that takes 2x 1.5V cells and any FM channel for "portable" occasional use.

Both kinds are amenable to RDS carrier injected via RC to the varicap. You can buy a pre-programmed PIC, use a TTL USB to Serial and feed the MP3 tags from Winamp out on USB via a plugin. However not much interest to users of 20 to 60 year old FM radio.

I regularly use my RP18 or RP25 in the bathroom fed on FM from elsewhere in the house. I have two old SD generic digital sat receivers 24x7 on FM on 19E and 28E and a third intermittent channel from MP3 playback.

[Keith]

Thank you for your most helpful replies - I'm pleased to say that some progress has been made. Following a squirt of Deoxit down the Gram socket I am now able to get audio into the Hacker. The plug has to be only partially inserted and a procedure akin to finding the sweet spot on a Galena crystal eventually gets a result. At some point I suppose I shall have to bite the bullet and remove the chassis to effect a proper fix. The result obtained, though, is most impressive. With the bass and treble controls at max, the output is excellent - especially considering that I'm just using a couple of rechargeable PP3 batteries. Indeed, my wife commented that it sounded far better than the DAB radio (Pure Evoke Flow) that she uses in the bathroom. I suggested that this was mainly down to the difference in the loudspeakers used - maybe size does matter, after all!

[Boulevardier]

Like others here, I'm pretty sure that the RP25 needs a longer jack plug (the lack of standardisation of these mini-jacks has been outrageous). I seem to remember that when I bought my RP25 in 1970, it came with one of the correct plugs taped inside, and that this was the only one that did the job..

I've recently been wondering if it's an easy job to replace the sockets with more standard type (without spoiling the appearance).

Mike

[buggies]

There is a comparative picture in this post:-
https://www.vintage-radio.net/forum/...47&postcount=4

and a source url in the following one:-
https://www.vintage-radio.net/forum/...52&postcount=5

Note that the part is B205 not 3-205 - it took me a while on the page to work that out.

[Jonster]

Have a look inside the radio - when they were new a special long reach jack plug was often supplied with the set, taped to the aerial, you may be lucky and find it is still there!

[Boulevardier]

Yes, Buggies' photo is very clear, and I can confirm that the bottom plug is exactly what was supplied by Hacker with my RP25 (I still have it somewhere). I'm not sure that there was any other source for them.

I've also had problems with recent stereo versions of these small jack plugs - e.g as fitted to stereo headphones - which haven't always fitted the sockets on some equipment.

Mike

[buggies]

Partridge still listing them at 79p.
3B-JS028 Mono 3.5mm Plug Metal B205 79p

[Keith]

Just to put this one to bed, I now have a fully working Gram input to the Hacker. Sadly, there was no plug taped to the aerial but I did find a correct sized one in my junk box (moral - never throw anything away!).

The reason the radio was not being muted was that a PO had bypassed the switch on the socket, presumably as it was not making reliable contact. Luckily, the Deoxit treatment has restored correct operation - other cleaners are available (they're just not as good!).

Thanks again for all your help. Looks like I'm all set for next year's bath

[nebogipfel]

- other cleaners are available (they're just not as good!).


Yes, but it's cheaper to buy a new radio

[Mike. Watterson]

Originally Posted by Keith

Thanks again for all your help. Looks like I'm all set for next year's bath

Great!

Whether you need it or not!

[ekjdm14]

Originally Posted by nebogipfel

- other cleaners are available (they're just not as good!).


Yes, but it's cheaper to buy a new radio

Indeed, I can't quite work out why Deoxit is so much more expensive than Servisol for example... And unless they (Caig) want to send me a sample to demonstrate why it's worth the extra, I'm afraid I will never know.