Thanks for the insight on the portables, I used to repair them circa 1964-67, all the ones I repaired were the small travel case types eg Pye, Vidor, Eveready etc.
Robert, is the volume control in that Wayfarer linked to any regen function?
Lawrence.
(07-10-2013, 06:20 PM)pwdrive Wrote: [ -> ]Robert, is the volume control in that Wayfarer linked to any regen function?
Yes it is a regeneration control. As I say I haven't actually powered it up and tried it, but here is the service sheet;
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attachment=9146]
Regards
Thanks Robert, a minimalist design.....It will probably work ok when up to spec, I like regens, so much for so little, must get my regenerodyne fired up again this winter and hear what the shortwaves are doing.
Lawrence.
Robert - re: your excellent collection of battery valve portables. Do they all feature in our Gallery? If not, perhaps you'd like to display them there? And if you do decide to do that and need any help in so doing - just ask me.
Thanks.
Al. / Skywave / Gallery Administrator / Oct. 7, 2013 //
Thanks Al, OK I'm sure I can get together some images for the gallery and upload them gradually when I've the time spare.
Regards
(06-10-2013, 03:35 PM)Robert Darwent Wrote: [ -> ]Typically in those using a DF97, the VHF tuner head circuit broadly follows thosed based around an ECC85 or UCC85 found in many common 50s mains only table sets, but in miniature of course.
... well, as far as the mixer is concerned. yes. But there's no front-end RF amplifier/buffer - the aerial is connected directly to the mixer (at a cunningly chosen oscillator null point, so that there's no oscillator radiation from the aerial).
(08-10-2013, 12:10 PM)Kalee20 Wrote: [ -> ] (06-10-2013, 03:35 PM)Robert Darwent Wrote: [ -> ]Typically in those using a DF97, the VHF tuner head circuit broadly follows thosed based around an ECC85 or UCC85 found in many common 50s mains only table sets, but in miniature of course.
... well, as far as the mixer is concerned. yes. But there's no front-end RF amplifier/buffer - the aerial is connected directly to the mixer (at a cunningly chosen oscillator null point, so that there's no oscillator radiation from the aerial).
...well, you are obviously referring to a specific model. My comments were generalised, it was the very reason I chose the words 'broadly follows'. There must have been several dozen VHF valve portables produced during the 1950s, your statement does not apply to all of them.
Regards
(08-10-2013, 12:10 PM)Kalee20 Wrote: [ -> ]But there's no front-end RF amplifier/buffer - the aerial is connected directly to the mixer
(08-10-2013, 03:02 PM)pwdrive Wrote: [ -> ]Here is the schematic for the Eveready Sky Emperor, looks like the VHF mix/osc pentode is triode strapped.
To clarify, there were at least 70 specific models of VHF battery valve portables produced during the 1950s period by several manufacturers.
My earlier reply regarding the use of either a DC90 or DF97 valve in the VHF tuner was not referring to any particular model, I was simply speaking in general terms to try and convey the obvious VHF tuner differences in models using the DC90 over the DF97.
The last two replies are clearly referring to one specific model or another - I wasn't.
Regards
I posted the Sky Emperor schematic up as the pentode appears to strapped as a triode and as such shows the similarity to the more conventional ECC85 self oscillating triode mixer used in mains sets.
It is indeed a design challenge for a VHF multiband receiver running on batteries.
Lawrence.