So this is a flat indoor antenna. It is very good. Brings in stations very clearly on my Dynatuner FM3 which is not known for exceptional sensitivity, as good as a dipole on my Tandberg 3001A. The FM3 does not do well with the dipole. I'm just curious if piggy backing two of these would be even more powerful?
For a receiver of any sort be it an old tube radio/ government communications receiver/ HAM radio receiver etc etc etc your aerial ( antenna ) RF input is tuned for a single aerial--UNLESS there are multiple aerial inputs for different RF impedance inputs which have onboard different tuned circuits .
No it will not make it "more powerful " but have you though of an aerial tuner which changes the input impedance of your aerial ?
I am talking of a passive unit , they were used long ago by defense forces for old communications receivers I have made several and I was able to boost signal strength quite a bit .
Correct home made dipoles require exact measurements to give the correct signal boost .
Tests of FM and DAB aerials - A.T.V. Poles, Brackets, Clamps & Aerials
No it will not make it "more powerful " but have you though of an aerial tuner which changes the input impedance of your aerial ?
I am talking of a passive unit , they were used long ago by defense forces for old communications receivers I have made several and I was able to boost signal strength quite a bit .
Correct home made dipoles require exact measurements to give the correct signal boost .
Tests of FM and DAB aerials - A.T.V. Poles, Brackets, Clamps & Aerials
Thanks for the response Duncan. Can you elaborate a bit on the variable impedance antenna? Is there such a thing on the market?
For FM, antenna height will add signal strength, and even a few feet can make a difference.
Have you touched up the adjustment screws on top of the main tuning capacitor?
They can make a big difference, but one is very touchy. Use a plastic tool.
Have you touched up the adjustment screws on top of the main tuning capacitor?
They can make a big difference, but one is very touchy. Use a plastic tool.
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Inside some FM receivers there should be impedance matching circuits but if not an impedance matching circuit is needed this can be very basic -
consisting of a series inductance and a parallel capacitance , I notice now separate antenna tuners are going out of fashion .
I have found a website with pretty cheap FM antenna which along with an inline FM amplifier would give a signal boost .
The connections are "F" type though the same as I use for satellite connections so if attached to a FM3 you would need a converter ( which are available ) to connect to it .
FM Amplifier: AP-FM (18 dB, shielded)
RHS for aerials .
I have used inline amplifiers for satellite .
consisting of a series inductance and a parallel capacitance , I notice now separate antenna tuners are going out of fashion .
I have found a website with pretty cheap FM antenna which along with an inline FM amplifier would give a signal boost .
The connections are "F" type though the same as I use for satellite connections so if attached to a FM3 you would need a converter ( which are available ) to connect to it .
FM Amplifier: AP-FM (18 dB, shielded)
RHS for aerials .
I have used inline amplifiers for satellite .
Here is everything technical including schematics of the Quad FM3 -
https://www.vintageshifi.com/repertoire-pdf/pdf/telecharge.php?pdf=Quad-FM3-Service-Manual.pdf
Well that was a stroke of luck ! this is a standard fault ( low signal ) and removing TR100 --the mute active device helped it but read all the posts.
Quad FM3 Tuner Weak - UK Vintage Radio Repair and Restoration Discussion Forum
https://www.vintageshifi.com/repertoire-pdf/pdf/telecharge.php?pdf=Quad-FM3-Service-Manual.pdf
Well that was a stroke of luck ! this is a standard fault ( low signal ) and removing TR100 --the mute active device helped it but read all the posts.
Quad FM3 Tuner Weak - UK Vintage Radio Repair and Restoration Discussion Forum
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Adjust them on a weak station for maximum eye closure in mono, see the manual alignment step #29.
One of the two is extremely tricky and must be done exactly right, or the sensitivity will be much
lower than it should be. It's not necessary to do any of the other steps when touching these up.
They have often been out of peak on most FM-3 kits I've checked. Use a plastic tool for best results.
http://www.tubes4hifi.com/Dynaco FM-3 manual.pdf
One of the two is extremely tricky and must be done exactly right, or the sensitivity will be much
lower than it should be. It's not necessary to do any of the other steps when touching these up.
They have often been out of peak on most FM-3 kits I've checked. Use a plastic tool for best results.
http://www.tubes4hifi.com/Dynaco FM-3 manual.pdf
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Thanks for informing me its a DYNACO FM 3 having looked a photos of the internals you will need a hexagonal adjuster but the final IF adjuster secondary connects to the ratio discriminator circuit trying to adjust that with equipment can end in complete loss of signal ---but maybe you will be lucky .
It isn't the professional way to do this and of course the aerial matching transformer will need adjusting .
It isn't the professional way to do this and of course the aerial matching transformer will need adjusting .
I honestly don't think there is improvement to be had since I just recently acquired it from a brick and mortar 'Natural Sound' stereo shop. It was checked over by their on hand tech before it was put out for sale. It seems to function flawlessly, the magic eye observably perfect. Stations are where they should be. It's just not as sensitive as the Tandberg 3001A but that's understandable considering the competition. With the flat antenna, the Dynaco does very well.
So this tuner does not need equipment to align it. User friendly serviceability is designed into it. I do have the manual. However, in order for a successful outcome I take it the individual components need to be up to spec.
Not talking about adjusting the IF strip or discriminator, just the 2 trim caps on top of
the main tuning capacitor. Those really affect the sensitivity, and must be set exactly right.
Most FM-3 tuners will not have weak components or even tubes. Some may need the alignment
to be touched up to work at their best. Hopefully the shop checked, but it takes over a half hour
to do an alignment, so some may skip it. If the tuning eye fully closes on most stations,
there's a good chance it is aligned well enough.
the main tuning capacitor. Those really affect the sensitivity, and must be set exactly right.
Most FM-3 tuners will not have weak components or even tubes. Some may need the alignment
to be touched up to work at their best. Hopefully the shop checked, but it takes over a half hour
to do an alignment, so some may skip it. If the tuning eye fully closes on most stations,
there's a good chance it is aligned well enough.
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Just the trimmers ?--that's a different matter --L1 is the impedance aerial/antenna adjustment ,its probably set to peak on 75ohms as that is more modern , the 300 ohm is for a dipole you can make yourself ( to the correct measurements).
It used to be you could buy a ready made aluminum tube dipole for connecting the ribbon cable --which is still sold on eBay/Amazon .
It used to be you could buy a ready made aluminum tube dipole for connecting the ribbon cable --which is still sold on eBay/Amazon .
That's perfectly normal. Full limiting (more noise) may not happen on stations that don't close the eye.
The L1 RF trimmer setting is not critical, and I've never seen it need readjustment.
I've built about a dozen of these tuners from kits, before they were discontinued by Dynaco.
Oddly enough, it's the only complete kit that Dynaco ever made. Their amplifiers and preamps
always had preassembled pcbs for some reason.
The L1 RF trimmer setting is not critical, and I've never seen it need readjustment.
I've built about a dozen of these tuners from kits, before they were discontinued by Dynaco.
Oddly enough, it's the only complete kit that Dynaco ever made. Their amplifiers and preamps
always had preassembled pcbs for some reason.
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Thats how all "magic eye,s" work Discopete its an old school way of showing signal strength to the general public in tube radios.
FM transmissions are directional like your TV antenna and must be aimed at the FM signal .
Looking at the spec . 4 microvolts isn't terribly sensitive my old tube communications receivers were much better than that so if you are not in a position of receiving a strong FM signal I suggest an FM aerial amplifier but it must be used in conjunction with a good aerial otherwise it would just boost noise.
FM transmissions are directional like your TV antenna and must be aimed at the FM signal .
Looking at the spec . 4 microvolts isn't terribly sensitive my old tube communications receivers were much better than that so if you are not in a position of receiving a strong FM signal I suggest an FM aerial amplifier but it must be used in conjunction with a good aerial otherwise it would just boost noise.
Would it be worthwhile to increase sensitivity by modding the circuit? Can it be done easily?
"Modding the circuit " have you got intensive knowledge and training in frequency modulation theory & practice --if not then don't do it .
This isn't some audio amplifier where you can dive in a make changes to the circuit in the belief it will still function--don't you realize even minute changes to the wiring etc can destroy the signal completely ?
We are talking TUNED circuits with inductance's set up by special equipment including "wobbulators " etc that's why I recommended an EXTERNAL solution I will let others tell you to go ahead .
Even replacement tube element capacitance can mean a re-alignment job .
This isn't some audio amplifier where you can dive in a make changes to the circuit in the belief it will still function--don't you realize even minute changes to the wiring etc can destroy the signal completely ?
We are talking TUNED circuits with inductance's set up by special equipment including "wobbulators " etc that's why I recommended an EXTERNAL solution I will let others tell you to go ahead .
Even replacement tube element capacitance can mean a re-alignment job .
Hi Duncan. I apologize if I gave you the impression I think it's par for the course. I was being rhetorical for lack of knowledge. I have no idea about what's possible, hence my query. So the Dyna Tuner is. I'm OK with that🙂