Season`s greetings to all...
While in England in `91, I picked up a Ford motor car radio receiver.
P21 79GB-18K810 HA . Two band , LW & MW .. (166 KHz - 285 KHz LW
& 666KHz - 1500Khz MW +/- ) .I would like to extend the LW band as
high in frequency as i can , and the MW band as low as i can in
frequency..I.F. is 465 kHz...Object : To create a beacon ( 200KHz -
400 KHz ) receiver...
Is there anyone out there that has any experience , and or ideas with
what i have in mind ?

TIA Gene WB7NGI

On Dec 27, 1:34*pm, Gene wrote:
Season`s greetings to all...
While in England in `91, I picked up a Ford motor car radio receiver.
P21 79GB-18K810 *HA . * Two band , LW & MW .. (166 KHz - 285 KHz LW
& *666KHz *- 1500Khz MW *+/- ) .I would like to extend the LW band as
high in frequency as i can , and the MW band as low as i can in
frequency..I.F. is 465 kHz...Object : To create a beacon ( 200KHz -
400 KHz ) receiver...
Is there anyone out there that has any experience , and or ideas with
what i have in mind ?

TIA * Gene * WB7NGI

If analog tuning then you add or remove capacitance to each LC and
hope that the padding can be adjusted or supplemented enough so that
everything (mixer and front end) tracks. It won't be so much
"extending" the tuning range but instead will be "shifting" the tuning
range.

If digital tuning then you'll have to locate the schematic for the PLL
chipset and see if you can convince the local oscillator to shift far
enough. With some PLL chipsets there are programming pins or diodes
that set the allowed range. In many cases, if you don't need the
original tuning range, you can patch in a divide by two or just change
the reference oscillator. If you change the reference oscillator then
the display won't be right but will be mathematically related to the
actual frequency.

I collect British tabletop radios and am quite familiar with their
longwave dial on tube-type analog sets (my favorite is when they do
not list frequencies but only wavelengths) but am not particularly
familiar with British car radios. My one piece of advice with respect
to car radios from foreign autos of 70's vintage or older, is to check
carefully WRT 6V or 12V and WRT to negative ground or positive ground.

Tim N3QE

On Dec 28, 12:38�pm, Tim Shoppa wrote:
On Dec 27, 1:34�pm, Gene wrote:

Season`s greetings to all...
While in England in `91, I picked up a Ford motor car radio receiver.
P21 79GB-18K810 �HA . � Two band , LW & MW .. (166 KHz - 285 KHz LW
& �666KHz �- 1500Khz MW �+/- ) .I would like to extend the LW band as
high in frequency as i can , and the MW band as low as i can in
frequency..I.F. is 465 kHz...Object : To create a beacon ( 200KHz -
400 KHz ) receiver...
Is there anyone out there that has any experience , and or ideas with
what i have in mind ?

TIA � Gene � WB7NGI

If analog tuning then you add or remove capacitance to each LC and
hope that the padding can be adjusted or supplemented enough so that
everything (mixer and front end) tracks. It won't be so much
"extending" the tuning range but instead will be "shifting" the tuning
range.

If digital tuning then you'll have to locate the schematic for the PLL
chipset and see if you can convince the local oscillator to shift far
enough. With some PLL chipsets there are programming pins or diodes
that set the allowed range. In many cases, if you don't need the
original tuning range, you can patch in a divide by two or just change
the reference oscillator. If you change the reference oscillator then
the display won't be right but will be mathematically related to the
actual frequency.

I collect British tabletop radios and am quite familiar with their
longwave dial on tube-type analog sets (my favorite is when they do
not list frequencies but only wavelengths) but am not particularly
familiar with British car radios. My one piece of advice with respect
to car radios from foreign autos of 70's vintage or older, is to check
carefully WRT 6V or 12V and WRT to negative ground or positive ground.

Tim N3QE

Tim, thanks for the reply...analog...made in Canada....so i assume it
is a Philco-Ford , unable to find schematic , will have to do some
reverse engineering to to figure out what cap , is what

Thanks , Gene WB7NGI

On Dec 29, 8:38*pm, Gene wrote:
Tim, thanks for the reply...analog...made in Canada....so i assume it
is a Philco-Ford , unable to find schematic , *will have to do some
reverse engineering to to figure out what cap , is what

Internally most of the good AM car radios I've met had mechanically
ganged slug tuning, although variable capacitor tuning existed too.

That's great if you're comfortable adjusting the mechanics of the
radio internally to get the tracking right. Remember, you won't be
broadening the tuning range, you'll be shifting the tuning range.

Tim N3QE

Tim Shoppa wrote:
On Dec 29, 8:38 pm, Gene wrote:
Tim, thanks for the reply...analog...made in Canada....so i assume it
is a Philco-Ford , unable to find schematic , will have to do some
reverse engineering to to figure out what cap , is what

Internally most of the good AM car radios I've met had mechanically
ganged slug tuning, although variable capacitor tuning existed too.

That's great if you're comfortable adjusting the mechanics of the
radio internally to get the tracking right. Remember, you won't be
broadening the tuning range, you'll be shifting the tuning range.

Tim N3QE


Í guess by about 1990 (20 years ago) they had all abandoned the
slug-tuned stages.

I had a '90 era car radio found in the Caribbean. It locked onto the
9kc European channels. I'm sure there was some chip jumpering that
would allow tuning to American 10kc channels but I never could find the
info.

On Dec 29 2009, 10:00*pm, Tim Shoppa wrote:
On Dec 29, 8:38*pm, Gene wrote:

Tim, thanks for the reply...analog...made in Canada....so i assume it
is a Philco-Ford , unable to find schematic , *will have to do some
reverse engineering to to figure out what cap , is what

Internally most of the good AM car radios I've met had mechanically
ganged slug tuning, although variable capacitor tuning existed too.

I once broadened the band of a Titan 4 reciever by
adding a varible capacitor with a spst it might need another varible
capacitor with a spdt to get the other end of the spectrum.


That's great if you're comfortable adjusting the mechanics of the
radio internally to get the tracking right. Remember, you won't be
broadening the tuning range, you'll be shifting the tuning range.

Tim N3QE

Hey OM:

The only way to make that work is with a converter.
Back in the day before police scanners, I made a converter that
converted the 70cm police band down to the AM broadcast band. 530Khz
thru 1600Khz was the band back then. My converter could put 3 local
police frequencies on the AM band.
All the converter is is an LO, input tank circuit, and a mixer. The
only active component was the LO. I used a CB rock which were dirt
cheap. Caught the 70cm harmonic into the mixer, getting the police
band down to the AM band.

I made a version that plugged inline with the car antenna and the car
radio, that could be switched in and out.
I couldn't make enough of them, Was the best selling product I ever
made.

73 OM
de n8zu



On Jan 5, 5:17*pm, joeturn wrote:
On Dec 29 2009, 10:00*pm, Tim Shoppa wrote:

On Dec 29, 8:38*pm, Gene wrote:

Tim, thanks for the reply...analog...made in Canada....so i assume it
is a Philco-Ford , unable to find schematic , *will have to do some
reverse engineering to to figure out what cap , is what

Internally most of the good AM car radios I've met had mechanically
ganged slug tuning, although variable capacitor tuning existed too.

I once broadened the band of a Titan 4 reciever by
adding a varible capacitor with a spst it might need another *varible
capacitor with a spdt to get the other end of the spectrum.



That's great if you're comfortable adjusting the mechanics of the
radio internally to get the tracking right. Remember, you won't be
broadening the tuning range, you'll be shifting the tuning range.

Tim N3QE

On Dec 27 2009, 3:34*pm, Gene wrote:
Season`s greetings to all...
While in England in `91, I picked up a Ford motor car radio receiver.
P21 79GB-18K810 *HA . * Two band , LW & MW .. (166 KHz - 285 KHz LW
& *666KHz *- 1500Khz MW *+/- ) .I would like to extend the LW band as
high in frequency as i can , and the MW band as low as i can in
frequency..I.F. is 465 kHz...Object : To create a beacon ( 200KHz -
400 KHz ) receiver...
Is there anyone out there that has any experience , and or ideas with
what i have in mind ?

TIA * Gene * WB7NGI

Based on the OP. Postulating some numbers!

The Long Wave band 166 to 285. That's ratio of 1:1.7
The local oscillator with an IF of 465 would be (465 + 166 = 631) to
(465 + 285 = 750) a ratio of only 1:1.18!

The Medium Wave band 666 to 1500. A ratio of 1:2.25
The local oscillator being (465 + 666 = 1131) to (465 + 1500 = 1965) a
ratio of 1:1.73.

To tune 200 to 400 khz. is a ratio of (at least) 1:2. And retaining
an IF of 465 would require, say, a local oscillator variation from
(465 + 200 = 665) to (465 + 400 = 865) a ratio of 865/665 or 1:1.3

However those 200 to 400 kilohertz aircraft beacon radios, covering
specifically 200 to 400 are quite often on eBay!

Another alternative would be a 190 to 550 kilo hertz ARC-5/BC453
'Command radio'. Those have 12 volt tubes that can easily be rewired
from 24 to 12 volt operation.

Another quicker alternative would be some form of small solid state
converter tuned or fixed into the Med. Wave band.